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Nitrogen is one of the most essential elements for crop growth. Nitrogen fertilizer has been widely applied to increase crop yields. At the same time, a large number of negative impacts have posed a great threat to the ecological environment in recent years. Among them, nitrogen leaching can be attributed to the excessive application of chemical fertilizers in farmland. Fortunately, the combined application of organic and chemical fertilizers can be expected to effectively reduce soil nitrogen leaching in normal fertilization during agricultural production at present. Therefore, this study aims to explore the combination application mode of organic and chemical fertilizers with a low risk of nitrogen leaching in farmland. The search terms were selected as chemical fertilizer, organic fertilizer, and nitrogen leaching using the two databases of China National Knowledge Infrastructure (CNKI) and Web of Science. The peer-reviewed and published papers were then obtained up to January 2022. Finally, a total of 35 papers (22 papers from Web of Science, 13 papers from CNKI) and 331 effective data pairs were collected after screening for the combination application of organic and chemical fertilizers in farmland. The target variables were taken as the total nitrogen (TN), nitrate nitrogen (NO3 - -N), and dissolved organic nitrogen (DON), while the chemical fertilizer was the control. After that, Metawin 2.1 software was used to determine the overall effects of the total amount of fertilization, fertilization structure (organic fertilizer substitution ratio), fertilization time (basic topdressing), and the types of organic fertilizers on the nitrogen leaching, where the chemical fertilizer was as the control. The results showed that there was a significant influence of the above fertilization behavior on nitrogen leaching. Once the total amount of nitrogen was less than 200 kg/hm2, the leaching of TN and NO3 - -N in farmland decreased by 36.77% and 65.05%, respectively. When the substitution ratio of organic fertilizers was higher than 70%, the TN leaching was reduced by 39.64%, whereas the risk of dissolved DON leaching increased by 15.78%. Especially, there was a 26.31% increase in DON leaching in the application of animal-based organic fertilizers combined with chemical fertilizers. Correspondingly, the application of nitrogen fertilizer significantly reduced the leaching of TN and NO3 - -N by 43.58% and 70.51%(P<0.05), respectively. A certain impact was also found in the soil pH and land use patterns on nitrogen leaching. For example, the combined application of organic and chemical fertilizers on the alkaline dryland soil effectively inhibited the leaching of TN and NO3 - -N, whereas, there was an increase in the leaching of DON by 26.63%-42.95%. Nitrogen leaching in dryland was dominated by the NO3 - -N leaching. By contrast, the emission factor (EF) was higher than that in the paddy field. The increasing replacement ratio of organic fertilizers can be expected to greatly reduce the soil nitrogen leaching in dryland, but to enhance the DON leaching. In addition, the Matlab software was used to analyze the importance of factors using the random forest model. Specifically, the replacement ratio of organic fertilizer demonstrated a dominant effect on TN leaching. There was also the more important effect of the nitrogen application level on the NO3 - -N and DON leaching. Therefore, the low level of nitrogen application and the high substitution ratio of animal-based organic fertilizers can be used to effectively reduce the soil nitrogen leaching loss in the alkaline dryland, compared with the chemical fertilizers only. The finding can provide the practical basis for the combined application of organic and chemical fertilizers in farmland. [ABSTRACT FROM AUTHOR]

High-clearance plant protection machine plays an important role in the large-scale chemical fertilizer spraying machinery in China. The wheels of high-clearance plant protection machine must be driven along the ridge during the working process. However, the driver's vision is blocked by corn plants, which is easy to cause corn seedlings damaged by tires. In view of the serious phenomenon of seedling injury during the operation of high-clearance plant protection machine, a method of real-time extraction of navigation line between the corn rows based on a dynamic Region of Interest (ROI) was proposed in this paper. According to the different growing periods of corn, the videos were collected when the average height of corn plant was 30, 50 and 70 cm under different light conditions. Through reducing the influence of light by pixel normalization, segmenting the image of corn and background by green image processing algorithm and the maximum class square error method, the images were enhanced and removed by morphological processing. Firstly, the collected image was divided into 10 image bands, and each image band was processed by vertical projection method to locate the center lines between crop rows in the first frame of the video. The approximate position of the static ROI was determined and marked based on the perspective principle of camera and geometric information of the corn seedling belts. It took 473.7 ms to divide the static ROI, which does not affect the real-time performance of navigation since the determined of static ROI was prior to the navigation operation. Secondly, the static ROI was applied in the second frame of video, in which the navigation line between the corn rows was obtained by sub-regional feature points clustering algorithm. According to the geometric information of navigation line and ROI, the ROI was updated and optimized. Then the updated ROI was applied to the navigation line extraction of the next video frame. 225 consecutive videos were selected to divide the ROI manually, and the dynamic ROI obtained by proposed method was compared with the artificial ROI. The pixel deviation between the artificial ROI and the ROI was about 10 pixels, which shown that the algorithm had good convergence and met the requirements of navigation accuracy. Finally, a comparative experiment of artificial navigation line extraction and the algorithm in this paper by randomly selecting 100 frames of image. The results showed that the algorithm proposed by this paper could automatically obtain the dynamic ROI, the average error of navigation line extraction between manual and algorithm in this paper was 1.157°, and the accuracy rate of corn seedling belt recognitionwas 96%, and the average processing time of a real-time image with a resolution of 1 920 pixels×1 080 pixels was 97.56 ms. July 16, 2019, the navigation experiment was carried out in corn field, and the heading angle was used as the input signal of the automatic steering control system. The results showed that the wheels of high-clearance plant protection machine walked along the corn rows, and the wheel angle floated up and down at 0°. The algorithm proposed in this paper can meet the accuracy and real-time requirements of the automatic walking for high-clearance plant protection machine in corn. [ABSTRACT FROM AUTHOR]

To implement systematic evaluation of land carrying capacity for livestock and poultry manure, prejudge its development trend and inspect the implementation effects of different emission reduction policies, this paper conducts the design and simulates different scenarios of land carrying capacity system model for livestock and poultry manure. Based on analyzing various subsystems of social economy, livestock and poultry breeding, crop planting and land carrying, and their elements, we established a system dynamic model of land carrying capacity for livestock and poultry manure, taking Shijiazhuang City as an example, which was an important city of animal husbandry in north of China. The system operation results indicated that: The model had good stability and reality, the error between the simulated value and the measured value was generally less than 10%. Therefore the model was effective. The system dynamic model was used to simulate the carrying capacity of livestock and poultry farming land in Shijiazhuang City from 2007 to 2025 under different scenarios. Five scenarios were designed. Scenario1: Inertial trend development condition, adjusting the economic structure of the animal husbandry, the investment in environmental protection, the proportion of manure and fertilizer and the mode of coordinated development, the simulation results show that: the output scale of animal husbandry and planting has increased, but the output growth of planting is inferior to that of livestock and animal husbandry, making it difficult for planting to consume nitrogen and phosphorus emissions by animal husbandry, and bringing more land carrying pressure. Scenario 2: Adjusting the economic structure of animal husbandry, both nitrogen and phosphorus balance carrying capacity present a downward trend, but phosphorus balance carrying pressure still exists. Scenario 3: Adjusting the environmental protection governance investment, nitrogen balance carrying is in the loadable state. Although the phosphorus balance carrying pressure is obviously decreased, only 8 years are loadable. Scenario 4: Adjusting the manure use ratio, nitrogen balance carrying is in the loadable state. The phosphorus balance carrying with improvement over the initial situation is still overloaded. Under the coordinated development mode, both nitrogen and phosphorus balance carrying pressure present a downward trend, both nitrogen and phosphorus balance carrying capacity are at the loadable level. It can be found through comparative analysis that the coordinated development mode has the best effect. This study provides support for carrying out monitoring and evaluation of livestock and poultry pollution and establishes an assessment mechanism for livestock and poultry breeding pollution on one hand. On the other hand, this paper provides scientific basis for the regulation and control of animal husbandry development in major livestock cities and other resources and environment overloading areas. [ABSTRACT FROM AUTHOR]

Huang-Huai-Hai region is the major superiority area of planting industry and breeding industry in China. With the increasing attention to the rural environment problems caused by crop straw and livestock manures, it is important to analyze “raising by planting” in Huang-Huai-Hai region, realize agricultural waste comprehensive utilization, and implement green development. “Raising by planting” was the core idea of this paper. The “raising by planting” calculation methods were as follow. First, technical regulations for production of wheat-corn and field research results in Hebei, Henan and Shandong provinces were used to summarize production model of wheat-corn in Huang-Huai-Hai region. So the conventional fertilization could be defined. According to test results of researches, this paper determined the amount of partial replacement of chemical fertilizer by organic manures. At the same time, thermophilic aerobic composting was chosen as techniques of livestock manure comprehensive utilization. The untreated amount of livestock manures was calculated. Then, the quantities of different species of livestock and poultry were calculated. According to the technical regulations, the amount of nitrogenous fertilizer were 532.5, 562.5 and 575 kg/hm2 in Hebei, Henan and Shandong provinces. The ratio of partial replacement of chemical fertilizer by organic manures was 30%. So the amount of replacement were 159.75, 168.75 and 172.5 kg/hm2. At the same time, there were no influence on grain security after the replacement of chemical fertilizer by organic manures. Due to the additional application of organic manures promoted soil nitrogen leaching risk, the environmental risk assessment of nitrogen in arable farmland was used. Nitrogen input mainly consisted of nitrogenous fertilizer, organic manure converted from livestock manures, seed, straw returning, atmospheric dry and wet deposition and irrigation water. Nitrogen output mainly consisted of grain and straw. Grade of environment risk in farmland in Hebei, Henan and Shandong provinces were all medium risk. Nitrogen loss rate of thermophilic aerobic composting fromlivestock and poultry manures was 42.26%. Other calculation parameters of livestock and poultry production, such as feeding period, population structure, were defined by many research papers. So in production model of wheat-corn in Huang-Huai-Hai Region, 6 dairy cows, or 18 beef cattle, or 47 to 51 swine, 731 to 789 laying hens or 8062 to 8705 broilers per hectare were land carrying capacity. Besides, at the field scale, various factors, such as soil fertility and soil microbial, might affect the ratio of partial replacement of chemical fertilizer by organic manures. So more researches were needed in the amount of replacement. On account of medium environment risk in farmland, lowering the risks was necessary. Nitrogen input structure: 46.3% chemical fertilizer, 27.5% straw returning, 19.8% organic manure, 4.0% atmospheric dry and wet deposition, 2.0% irrigation water and 0.4% seed. So reducing straw returning was one of risk solutions. In simulation results, reducing corn stalk or wheat straw both lowered environment risk effectively. The results provide a reference for planting and raising combination in Huang-Huai-Hai region. [ABSTRACT FROM AUTHOR]

In China, the agricultural non-point source pollution threatening water environment is a serious problem. The main agricultural non-point source pollution sources include fertilizers, pesticides, straws, mulching films and livestock and poultry mature. The characteristics of the agricultural non-point source pollution in different provinces are different. The paper was to study the characteristic and development tendency of the agricultural non-point source pollution in Qinghai province based on the history data and export coefficient method. Qinghai province is located in the northeast of Qinghai-Tibet Plateau. It has the characteristics of low temperature, large gap in temperature between day and night, less and concentrated rainfall, long sunshine and strong solar radiation. In Qinghai province, many mulching films are used and large numbers of livestock and poultry are dispersedly raised in pastoral and semi-pastoral areas. With the development of agriculture and animal husbandry, the problem of agricultural non-point source pollution has become more obvious. The pollution loads including 4 parameters of chemical oxygen demand (COD), ammonia nitrogen (NH3-N), total nitrogen (TN) and total phosphorus (TP) produced by fertilizers, straws, livestock and poultry had been calculated. Considering the special situation that there were many livestock and poultry by dispersion raising in pastoral and semi-pastoral areas, the calculate methods of the agricultural non-point source pollution of livestock and poultry under different breeding modes were proposed. The pollution contributions and threats of the different pollution sources were revealed and the main prevention measures were given. The results showed that fertilizers and pesticides consumption, crop and straw yield, plastic mulch, livestock and poultry manure had presented an increased tendency in the past 30 years and the crop and straw yield had slowly declined in the past 5 years in Qinghai province. In 2015, the total nitrogen (TN), total phosphorus (TP) pollution loads and ammonia nitrogen (NH3-N) produced by fertilizers were 2721, 217 and 226 t, which were 2%,15% and 2% higher than that in 2013. When the fertilizer efficiency increased to 40%, the TP load was still larger than that in 2013. The TN and TP loads produced by crop straws are 2 418 and 224 t respectively which were close to the fertilizers in 2015. The COD load was 1889 t. Oil crops produced the largest pollution, beans and tuber crops produced less pollution in Qinghai province. The COD, NH3-N, TN and TP loads produced by livestock and poultry were 1289.1, 8.5, 350.4 and 51.8 thousand ton. Under different breeding modes, the agricultural non-point source pollution load produced by small-scale rear livestock in pens was the maximum, and the NH3-N pollution loads from the large-scale breeding sites and specialized households were large，the NH3-N and TP pollution loads from the free-ranging livestock and poultry were also noticeable. In 2015, 98.8% of COD, 90.2% of NH3-N, 93.8% of TN and 93.9% of TP of agricultural non-point source pollution loads were produced by livestock and poultry manure. Additionally, based on the Environmental State Bulletin of Qinghai province, we obtained that the agriculture non-point pollution was the main source of COD which contributes 66 percentages of the total COD loads in 2015. In view of the main prevention measures, the pollution control of the animal husbandry should be strengthened, an ecosystem circulation mode considering the combination of crop farming and animal husbandry combination should be built. This paper can provide valuable information for the agricultural non-point source pollution control in Qinghai province. [ABSTRACT FROM AUTHOR]

Water and fertilizer are indispensable inputs to crop production in modern agriculture. Drought, water shortage and low efficient utilization of water have posed a great challenge on agricultural production and food security in China. New fertilizers with dual functions of water retention and slow release become significant to enhance the utilization efficiency of water, and thereby to ensure the sustainable development of agriculture. Therefore, previous studies on the new fertilizers have drawn much attention in water and fertilizer technology in recent years. This paper explores the preparation method of a novel water-retaining material that incorporated with nano-SiO2 for the slow-release fertilizer with water retention properties. A P(AA-AM)/SiO2 water-retaining composite was fabricated by in-situ polymerization in aqueous solution using acrylic acid (AA) and acrylamide (AM) as raw materials. A water-retaining slow-release fertilizer was then produced by the double-layer coating process. The mass ratio of acrylic acid (AA) and acrylamide (AM) was set as 3.5:1 to synthesize water-retaining materials. The initiator (potassium persulfate and sodium sulfite), crosslinking agent (N, N-methylenebisacrylamide), plasticizer (glycerol), and nano-SiO2 were added by 1%, 0.04%, 15%, and 2% in monomer mass, respectively. A drum coating process was selected to prepare the water-retaining slow-releasing fertilizer, where the inner coating layer was made of polyurethane, with the mass ratio of coating materials to the inner core of 3%, whereas the outer coating layer was P(AA-AM)/SiO2 water-retaining composite material, with a mass ratio to the core of 27%. Fourier Infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetry (TG) were used to characterize the microstructure, morphology and thermal stability of water-retaining materials. A filtration was selected to determine the water absorption of water-retaining material. Soil culture experiment was used to investigate the capacity of water-retaining and water-holding in the fabricated fertilizer. A water immersion method was utilized to explore nitrogen release properties of fertilizer at the temperature of 25℃. The results showed that the water absorption rates of composite materials with nano-SiO2 in deionized water and 0.9% NaCl aqueous solution were 152% and 87% higher than those of only P(AA-AM) materials, while the thermal stability was also significantly improved. SEM images and FTIR analysis indicated that nanoparticles of SiO2 were evenly dispersed into the P(AA-AM) composites, while the silicon hydroxyl groups on the surface of SiO2 increased the cross-linking density of water-retaining materials. Compared with the slow-release fertilizer without water-retaining layer, the water absorption rate and retention rate of slow-release fertilizer with water-retaining layer (after 25 days of incubation) increased by 25.5% and 47.2%, respectively, indicating the releasing duration of fertilizer was extended from 60 days to 72 days. The preparation method of water-retaining composite material that incorporated with nano-SiO2 and water-retaining slow-release fertilizers can provide excellent properties of water absorption and retaining, as well a high performance of slow release in soil. A mechanism of water-retaining was proposed to clarify the slow release of nutrients in the water-retaining material and water-retaining slow-release fertilizers. The findings can offer new insights into high efficiency fertilizers to enhance the utilization efficiency of water and fertilizers. [ABSTRACT FROM AUTHOR]

In recent years, the pneumatic centralized fertilizing and seeding methods were developing rapidly. The pneumatic centralized fertilizing system was mainly used for layered fertilizing operation. The fertilizing pipes of the fertilizer discharging system were connected with the fertilizer outlet of the layered fertilizing shovel. Under the actions of air flow, the fertilizer was transported to the outlet of the fertilizing shovel quickly and remotely, so as to realize the layered application of the fertilizer in the soil. In this paper, in view of the problems such as the fertilizer falling into the inlet was not smooth and the airflow velocity at the outlet was too high, which leading to fertilizer bounce and dust when the fertilizer discharging system and layered deep fertilizing shovel were combined, the relationship between the structure of each part of the fertilizer discharging system and the working parameters was studied through the test-bench of the pneumatic centralized fertilizer discharging system, and the structure of the fertilizing system was optimized. An air-fertilizer separation device was designed, which was installed between the distributor outlet and the fertilizer discharging pipe of the layered deep fertilization shovel, part of the airflow from the fertilizing system was discharged by the air-fertilizer separation device in advance to reduce the airflow velocity at the fertilizer outlet of fertilizing system. The structure and basic working parameters of each component of fertilizing system were determined through theoretical analysis and parameter calculation. In specific, the airflow velocity of the fertilizing system inlet should be greater than 25 m/s, the diameter of the air-fertilizer conveying pipe, fertilizer inlet and fertilizer outlet was 76, 55 and 20 mm, respectively. The main factors affecting the airflow velocity at fertilizer outlet and inlet of fertilizing system were also determined through analysis. Taking the exhaust outlet area of the air-fertilizer separation device (A), the airflow velocity of the fertilizing system inlet (B) and the fertilizing rate (C) as the test factors, the quadratic regression rotary orthogonal platform experiment was conducted. According to the test results, the mathematical regression model between the test indexes and the influencing factors was established. The results showed that the exhaust outlet area of air-fertilizer separation device, airflow velocity of the fertilizing system inlet and fertilizing rate had a significant effect on airflow velocity at fertilizer outlet of fertilizing system, and exhaust outlet area of air-fertilizer separation device had a significant effect on the airflow velocity at inlet of fertilizing system. The optimized parameters were conducted by fitting and optimizing the test results. It was obtained that airflow velocity at fertilizer outlet, fertilizer inlet of fertilizing system was 5.91 and 3.94 m/s, respectively, the exhaust outlet area of the air-fertilizer separation device, airflow velocity of the fertilizing system inlet and fertilizing rate were 798.0 mm², 28.10 m/s and 0.28 kg/s, respectively. The verification test results showed that the airflow velocity at fertilizer outlet and fertilizer inlet of the system was 6.02 and 4.11 m/s, the fertilizer at the inlet of the fertilizer discharging system falled smoothly and stably. [ABSTRACT FROM AUTHOR]

There are a lot of blind application of chemical fertilizers in the planting of bananas, which leading to waste of fertilizers and environmental pollution. According to the distribution pattern of banana root system, a variable fertilizer apparatus was designed in this paper. Based on the image processing of banana root morphology and the statistics of the area area pixels, the distribution pattern of the banana root system in the horizontal direction was analyzed. Based on the characteristics of the root area distribution, the change of fertilization amount along with the root distribution in horizontal was normally distributed, that is, the amount of fertilizer in the main root was the largest. Based on this, a rotary plate variable fertilizer apparatus was designed. By calculating the fertilizer amount distribution discharged on the simulated ground by the simulated fertilizer discharger, it was determined that the distribution law of the fertilizer amount along the forward direction of the machine was also normally, which was the same with the banana root distribution. In order to ensure that the fertilizer discharging amount and the center position of the normal distribution of the root are consistent in space, taking the spatial consistency of the center positions of the two normal distribution as the goal, the operation process planning was carried out for the image acquisition interval time, algorithm time, motor response time, fertilizer falling time, etc., and the accompanying operation control model of the machines was established. The variable control system was used to achieve and ensure that the center positions of the two normal distributions were consistent in space. The center combination simulation test was carried out with the movement speed, the moving period of the rotating plate, the central angle of curved slot and the opening size of curved slot as independent variables, and the length of fertilizer distributing and the fertilizer discharge amount were used as test response values. The result of optimal parameter combination was that the movement speed is 0.25 m/s, moving period of the rotating plate is 10.00 s, the central angle of curved slot is 90.00°, and the opening size of curved slot is 20.00 mm. The model and test errors, simulation and test errors of the length of fertilizer discharge are 4.98% and 3.30% respectively, the model and test error, simulation and test error of fertilizer discharge amount are 11.15% and 6.68%, respectively. The field test was conducted to examine the field operation effect of the fertilizer discharger, the average qualified rate of fertilizer discharging length was 96%, the average qualified rate of fertilizer discharge amount was 95.33%，the operation performance of fertilizer apparatus was good. [ABSTRACT FROM AUTHOR]

The mechanized seeding operation is an important part in modern agricultural production, and the net operating time utilization rate of the seeder is an important indicator to impact the efficiency of seeder unit. According to machinery unit application principle, the new term of seasonal net time utilization rate was determined in this paper, each consumed time items of seeder unit was distinguished and relevant mathematic models were established based on mechanized seeding practice and sufficient survey, such as net operating time, turning time and time of adding fertilizer and seeds and so on. Based on this, three mathematical models of net operating time utilization rate of seeding machinery units were established according to different adding fertilizer and seed ways. The experiment scheme was designed, which uses the method of multi-point synchronous tracking measurement to test the time items in the seeding process without disturbing the normal seeding process. Data of each time items of 4 typical seeding machinery units were obtained during the experiments. The statistic principle of 3ᓂ was used to distinguish and eliminate invalid experiment data. Based on the models established and effective tested data, Matlab 2012b was used to analysis the net operating time utilization rate of the 4 seeding machinery units changing with plot length and area under 3 different ways to add fertilizer and seed, the test results were expressed using Sigmaplot 12.5 software, and th quantitative correspondence between the different typical seeding machinery units and suitable operating plot area and length under the aimed net operating time utilization rate were determined. The results showed that when the aimed net operating time utilization rate of seeding machinery units is greater than 0.6, the John Deere 7 830 unit is suitable for the plots with areas no less than 6 hm² and the plot length is 1 200-1 400 m. The Valtra 171 unit is suitable for the plots with area no less than 6 hm² and the plot length is 1 000-1 200 m. The suitable plots for Changfa 504 unit are that area is no less than 1 hm²and the plot length is 500-1 500 m. The plots with area no less than 0.3 hm² and the plot length is 200-1 500 m are suitable for Huanghai 254 unit. The results can provide scientific accordance to select seeding machinery units for different plots. [ABSTRACT FROM AUTHOR]

The problem of environmental pollution caused by excessive use of chemical fertilizers has seriously restricted the sustainable development of green-oriented agriculture in China. Quantitative and uniform mechanized fertilization as an important measure to improve the utilization rate of chemical fertilizers and reduce the amount of chemical fertilizers has become an important way to solve agricultural environmental pollution. In this paper, a spiral disturbance cone centrifugal chemical fertilizer apparatus was designed to solve the problem of precision fertilization due to the insufficient fluency and stability of the fertilizer apparatus fertilizing processes and insufficient uniformity of fertilizer discharge. First of all, the design principles and working principles of the fertilizer apparatus is illustrated. Then the structural parameters of the spirally disturbance cup and curved cone disk are designed, based on the physical and mechanical properties of the granular fertilizer and the requirement of fertilization for rapeseed sowing. Moreover, fluency, uniformity and stability of the fertilizing performance are verified by bench test and field test. The SINO-AGRI fertilizer, STANLEY fertilizer and EZHONG fertilizer are respectively used as experimental materials to carry out the bench test of the fertilizer apparatus. The rotational speed of cone disc measured by SW6234C laser speedometer, there are total 6 levels, are 80, 90, 100, 110, 120, 130 r/min. Coefficient of variation of fertilizing amount consistency in every row, the coefficient of variation of fertilizing amount stability and coefficient of fertilizing amount consistency in same row are used as the evaluation index in the bench test for evaluating fluency, uniformity and stability of the fertilizing performance. The test results of bench show that the variation coefficient of fertilizing amount in every row of three compound fertilizers is below 11.5%. The coefficient of variation of fertilizing stability under chemical fertilizer conditions with different rotational speeds and physical and mechanical properties is below 6.3%, and the variation coefficient of fertilizing amount in same row is above 93%. Therefore, the fertilizer apparatus meets the quality requirements of fertilizer discharge. Meanwhile, variation coefficient of fertilizing amount in every row is 9.82% when the rotational speed of cone is low and the fertilizer apparatus is tilted, that means that the fertilizer apparatus still has better fertilizing performance in the inclined state. The adaptability applied to a narrow-width fertilizing machine of less than 8 rows is weak. The cone disc is successively rotated through the 1 to 8 row of fertilizer tube. When the rotational speed of cone disc is low, the next discharge tube of the blocked fertilizer pipe has a larger amount of fertilizer, the amount of chemical fertilizer in the other fertilizer pipes is basically the same, and the difference in the amount of fertilizer discharged from each row of fertilizer pipes is small. While the rotational speed of cone disc is high, the previous discharge tube of blocked has a larger amount of fertilizer, the difference between the fertilizing amount of this discharge tube and other discharge tube is larger, the amount of fertilizer in the other fertilizer tube is basically same. Furthermore, the field test was carried out to verify the fertilizing performance of the spiral disturbance cone centrifugal fertilizer apparatus. The results of field experiment show that the variation coefficient of fertilizing amount in every row is below 7.9%, the coefficient of variation of fertilizing stability is below 5.3%, the variation coefficient of fertilizing amount in same row is above 93.5%. This research provides effective technical support for chemical fertilizer reduction and precision fertilization. [ABSTRACT FROM AUTHOR]

Shajiang black soil is a typical middle and low production soil in Huang-Huai-Hai Plain. Crop production has been seriously restricted due to the high clay contents and low available water capacity of Shajiang black soil, this paper studied the effects of different modified materials on soil water holding capacity and wheat physiology of anti-drought stress by wheat pot experiment carried out in March 2018, in order to provide technical supports for farmland water managements. According to local field fertilization and water management modes, 4 treatments were designed in wheat pot experiment: chemical NPK fertilizer (CK), chemical NPK fertilizer with maize straw returning (SR), chemical NPK fertilizer with maize straw carbon (SC), and chemical NPK fertilizer with fly ash (FA). Referring to conventional amount of applying fertilizer in northern farmland in Anhui province, the application amounts of chemical fertilizer were 225 kg/hm² (N), 120 kg/hm² (P2O5), and 60 kg/hm² (K2O), respectively, and the application amounts of fly ash, maize straw carbon, and maize straw returning to field were 45×10³ kg/hm², 45×10³ kg/hm² and 6×10³ kg/hm², respectively. As for wheat pot experiment, in each pot, about 10 wheat seeds were transplanted into 30 kg soil after accelerating seeds germination. Soil relative water content was maintained at 80% field capacity until heading stage. When wheats grew up to the heading stage, irrigation stopped and then a drought stress experiment was carried out for 10 days. Wheat leaves collected regularly were stored at -80 ℃ so as to determine wheat physiological and biochemical index. The results showed that both SC and SR improved soil water holding capacity, but both was not significantly different. Owing to the abundance of large amount of hydrophobic crystal minerals like the crystallographic silicon dioxide in the surface of fly ashes, FA had a fast decrease in relative soil water content. The delayed water content of FA was significantly lower than the other treatments, while the available water content was significantly improved. What’s more, different modification materials all had the tendency to increase saturated water content and alleviate the impairments of wheat leaves caused by drought stress. Under mild drought stress, the saturated water content of wheat leaves was higher than that of the control group, but no significant difference was found in the contents of proline (PRO), malondialdehyde (MDA), hydrogen peroxide (H2O2) and peroxide scavenging coenzyme in the wheats among the four treatments. However, under extreme drought stress, not only was FA significantly lower than the other treatments in wheat leaves saturated water content, but also FA treatments accumulated more harmful substances like MDA and H2O2 in wheats, which could lead to irreversible damages to wheat physiological conditions. In conclusion, the relative water content of Shajiang black soil was suggested to keep above 38% (SR), 36.5% (SC) and 24.5% (FA), respectively. The plant physiology would get irreversible damage if relative soil water content was under 30.78% (SC), 28.43% (SR) and 22.5% (FA), respectively. Because straws have better performance in holding water by significantly improving the content of soil capillary pore, and fly ashes can do better in providing more available water for soil in spite of holding water poorly, combined application of straws and fly ashes will be conducive to the improvement of Shajiang black soil. Relevant mechanism need to be furtherly studied. [ABSTRACT FROM AUTHOR]

Hydraulic project alerts hydrological cycle and changes biochemistry of water as a result. In this paper, we investigated the change in groundwater chemistry in Qinwangchuan basin as affected by the Yindaruqin irrigation project. Groundwater samples were taken from the basin and were chemically analyzed before and after the irrigation project was in operation. The change in groundwater chemistry was analyzed using methods including statistics, Gibbs graphs and ions ratios. The results showed that the coefficient of variation (CV) of all main ions was larger than 10%, with their CV in the plain area being higher than that in the loess hill area. The total dissolved solids in the groundwater were currently high, with Na+ being the dominant cation and Cl- and SO4 2- the dominant anions. Salty and brackish water was found in most parts of the basin, and fresh water with total dissolved solids less than 1.0 g/L existed only in the middle of the basin. The total dissolved solids in the groundwater decreased from the loess hills at the edge of the basin towards the central plain area, and the associated hydro-chemical type of the groundwater changed gradually from Cl·SO4- Na type to HCO3·SO4- Na type. Before the irrigation project was constructed, the main geochemical type of the groundwater was Cl·SO4- Na, Cl·SO4- Na·Mg and SO4·Cl – Na. At earlier operating stage of the project, leaching of soluble salts from the topsoil led to an increase in total dissolved solids and hardness in the groundwater. With the decrease in soluble salts in the topsoil due to leaching, however, the total dissolved solids in the groundwater have been in decline since 2009, especially in the center of the plain where the total dissolved solids in the groundwater in some areas had reduced to < 1.0 g/L from > 3.0 g/L and the groundwater type changed from Cl·SO4-Na to HCO3·SO4- Na, HCO3·SO4- Na·Ca·Mg, and Cl·SO4·HCO3- Na, respectively. In contrast, the groundwater chemistry in the loess hills at the edge of the basin did not show significant change due to limited irrigation, and its chemical type is still Cl·SO4-Na·Mg despite a slight increase in total dissolved solids and total hardness. The groundwater type at Dangpu area in the southern basin changed from Cl·SO4-Na to Cl·SO4-Na·Mg, with a light decrease in total dissolved solids and total hardness. The change in groundwater chemistry in the Qinwangchuan basin is affected by both natural and anthropogenic factors. The infiltration and salt leaching due to irrigation increased the total dissolved solids in the groundwater initially followed by a dilution. Rock weathering and dissolution of minerals increased the total dissolved solids, and groundwater evaporation also increased the total dissolved solids in areas where the groundwater table was shallow. The ions in the groundwater originated from silicate weathering and dissolution of halite, along with the evaporation-induced condensation. Industry did not affect groundwater chemistry but the application of chemical fertilizer led to an increase in NO3- in the groundwater. These results provide a useful dataset for sustainable management of the groundwater resources in proximal areas of the Qinwangchuan irrigation project. [ABSTRACT FROM AUTHOR]

Differential pressure tank is a widely used fertilization device in the application of fertilization in China and many other countries. However, the fertilizer concentration in the tank continuously decays with the inflow of water. The decay feature of fertilizer concentration can easily lead to excessive fertilization at the head and insufficient fertilization at the end of the irrigation system. An analytical solution was proposed in this paper to achieve uniform fertilization based on differential pressure tank with constant fertilizer concentration and flux. The relationship between the uniform fertilization analytical solution and the fertilizer continuity equation was obtained based on differential pressure tank. The analytical solution was expected to control the flux flowing into the differential pressure tank and the flux directly flowing into the irrigation system through the main pipe according to 4 parameters: Uniform fertilizer concentration, initial fertilizer concentration, the volume of differential pressure tank and the total fertilization flux of the main pipe. Based on the analytical solution, the fertilizer continuity equation and the incompressible continuity and momentum equations of water were used for describing the movement of mixture in the differential pressure tank. The numerical model for mixed water and fertilizer flow in the differential pressure tank was determined by experimental data. The fertilizer concentration simulated by numerical model was nearly uniform in the tank and the fertilizer concentration at tank outlet obtained by numerical model decayed with a negative exponential pattern as described by Feng’s theory. The numerical simulation results directly verified the accuracy of the basis of Feng’s theory. The differential equation was also the basis of the uniform fertilization. The mean absolute error between the differential equation and the experimental data was less than 0.041 when the boundary condition of traditional fertilization method was substituted into the differential equation, which indirectly proved the rationality of uniform fertilization method satisfying the boundary conditions of constant fertilizer concentration and flux. The analytical solution’s feasibility in the uniform fertilization process based on differential pressure tank was simulated by the numerical model of fertilizer solution in determining the uniform fertilizer concentration and the fertilization time. The fertilizer concentration at tank outlet simulated by the numerical model decayed almost linearly and agreed with the uniform fertilization analytical solution. The fertilizer concentration simulated by the numerical model at drip irrigation system inlet was almost uniform and in agreement with the analytical solution of uniform fertilization. The relative bias of fertilizer concentration between the analytical solution and computation calculated by the numerical model was less than 15%, which verified the feasibility of uniform fertilization method based on differential pressure tank. The results showed that the application of uniform fertilization method and the uniform fertilization method could basically achieve constant fertilizer concentration and flux based on differential pressure tank. According to the actual product, the relationship between valve opening and time could be obtained in order to realize the control of valve opening process by computer. Approximately 70% to 80% of fertilizer in the normal operation was within range of the excessive or insufficient amount, whereas the uniform fertilization method could effectively avoid the waste of excessive fertilization and the lack of insufficient fertilization. [ABSTRACT FROM AUTHOR]

Wheat straw returning is one of the main ways to improve soil fertility. Long-term straw returned to field combined with chemical fertilizer can maintain soil fertility. It should be combined with crop rotation system and fertilization management to maximize advantages and avoid disadvantages. The impact of straw returned to field on crop yield and how to fertilize when straw returning are the issues of great concern to agricultural producers. In order to clarify the effect of long-term straw returned to field in wheat-bean rotation on crop yield and soil nutrient, this paper conducted the experiments in the long-term positioning experimental station in Heihe district of Heilongjiang province, and adopted split-plot test method. The main treatment was straw returning to field and non-returning to field, secondary treatment was different fertilization for low, medium and high level. The experiment started in 1980 with wheat-soybean-wheat and wheat-soybean rotation models. The effects of wheat straw returning to field and different fertilization levels on crop yield under wheat-soybean rotation conditions were investigated for 38 consecutive years (1980-2018). The results showed that there was no significant difference in years of yield of wheat, soybean or wheat planted every other year after wheat straw returning. The medium-fertilizer was 7.42%-10.81% higher than that of low-fertilizer area on soybean with continuous fertilization, achieved significant difference level. The yield of wheat increased by 14.52%-19.33% in high-fertilizer area compared with low-fertilizer area. The effect of wheat straw returning on soybean yield was 5.91% higher than that of non-returning in the early stage (1-6 season) and 7.52% higher in the late stage (7-16 season). The yield of wheat increased by 0.31% and 0.22% in early stage (1-5 seasons) and late stage (6-16 seasons) compared with non-returning to field. Generally speaking, after wheat straw returning to the field, the frequency of crop yield reduction in the early stage is high, while the frequency of yield increase in the later stage is high. In Heihe area, the long-term application of wheat straw to field had no significant effect on soil organic matter, total nitrogen, alkali nitrogen, total phosphorus, available phosphorus and total potassium, while the content of available potassium increased significantly. Long-term fertilization had a significant impact on soil nutrients. High fertilizer level could significantly increase the contents of soil organic matter, total nitrogen, alkali nitrogen and total phosphorus. Long-term fertilization also reduces soil pH value, leading to acidification of soil. [ABSTRACT FROM AUTHOR]

Soil respiration is mediated by microbial activities, temperature, humidity and other environmental factors in soil. The increase in use of microbial organic fertilizer and drip irrigation in greenhouse production could alter soil micro-environment, particularly the rhizosphere, thereby leading to a change in soil respiration. This paper investigated the response of soil respiration to different combinations of drip irrigation amounts and microbial organic fertilizer applications. We experimentally compared three irrigation amounts 15, 18 and 21 mm – associated with three microbial organic fertilizer applications 2800, 3600 and 4400 kg/hm². The treatment with inorganic fertilizer application served as the control. In each treatment, we measured soil respiration rate and accumulated carbon emission, as well as other determinants. The soil temperature and humidity were measured following the soil respiration measurement using the delta-T sensor (delta-T company, UK); soil organic matter was measured using the potassium dichromate sulfuric acid oxidation external heating method; the activity of dehydrogenase was determined using the TTC colorimetry method; the activity of urease was determined by the phenol sodium colorimetry method; the activity of catalase was determined by the KMnO4 volumetric method. We analyzed the responsive change in soil respiration to these determinants and root biomass. The results showed that, compared to the CK, drip irrigation and microbial organic fertilization improved soil organic matter and increased the activities of dehydrogenase, urease and catalase by 11.6%-27.6%, 8.0%-27.7% and 1.8%-11.2%, respectively; the increase in urease activities was at significant level (p<0.05). The soil respiration rate was positively correlated to the root biomass, temperature and organic matter content at significant level of p<0.01, and to the enzymatic activities at significant level of p<0.05. Among all treatments, irrigating 18 mm of water and applying 4400 kg/hm² of microbial organic fertilizer produced the highest root biomass, reaching 394 g/m² 120 days after the transplanting. Overall, combining drip irrigation and microbial organic fertilization increased root biomass by 25.9%-43.4%, compared to the CK. When irrigation amount was 15 and 18 mm, the carbon emission increased significantly (p<0.05) when the fertilizer application increased from 3600 kg/hm² to 4400 kg/hm². The cumulative carbon emission peaked at 415.2 g/m² when the irrigation amount was 18 mm and the microbial fertilization was 4400 kg/hm², significantly higher than that under other treatments (p<0.05). The lowest cumulative carbon emission was from the CK, being 255.3 g/m² only. In summary, this study showed that drip irrigation and microbial organic fertilization combined to impact soil carbon emission by changing organic matter content and root biomass in the soil. Our results have important implications for improving ecological cultivation in greenhouse production. [ABSTRACT FROM AUTHOR]

The integration of fertilizer and water technology is one of the important means to improve the effective utilization rate of chemical fertilizers. The solenoid valve control mode based on pulse width modulation is the main technical means to adjust the amount of suction flow. But at present, the researches of scholars at home and abroad mainly focus on these 3 aspects: Water-fertilizer coupling effect test, venturi structure optimization and performance analysis, water and fertilizer machine pipeline design. And the venturi suction characteristics in the solenoid valves switch on and off mode was little concerned. In this paper, on the 5-channel pipeline online mixed water and fertilizer integration test platform, the hall flow sensor was used to test the instantaneous flow of single channel in the valve opening time of 0.3, 0.5, 1 and 2 s. The average flow of single switch under different valve opening and closing time. The average flow under 10 consecutive switches was calculated by pulse correction method. All the pulses and the time elapsed for each pulse were collected and recorded, and the flow rate was calculated according to the pulse total number, effective pulse number and the pulse correction respectively. The actual flow was measured by the electronic scale and compare with the calculated values of the 3 methods respectively. The results showed the relative error of the flow rate calculated by the total pulse number method was much larger than the effective pulse method and the pulse correction method, but the relative error decreases with the increase of the valve opening time. Compared with the total pulse number method, the measurement accuracy of the effective pulse method was greatly improved. The accuracy of the pulse correction method was the highest, the relative error was less than 4% during the valve opening duration of 0.3-2 s, and the pulse correction method was more advantageous when the valve opening duration was shorter. The suction characteristics test results showed that in the continuous switch mode of the solenoid valve, the shorter the valve closing time, the smaller the total number of pulses and the average flow rate. The average flow rate of each valve decreased rapidly with the valve opening time increasing. when the valve opening time was longer than 5 s, the average flow rate of fertilizer absorption tended to be stable at 10 L/min. In the combined structure of venturi and fertilization pump, the greater the fertilization pressure, the smaller the suction flow, but no significant effect on the energy storage and discharge process of the venturi injector. During the maximum energy storage and discharge time, the amount of suction flow by the venturi injector decreased with the prolonging of the valve opening time, and increased with the prolonging of the valve closing time. The test results of the venturi injector under the single switch showed that the maximum energy storage time (vacuum) of the venturi injector was 10 s, and the maximum energy release time (the time when the suction flow was stable) was 1 s. This research can provide technical support for the design and application of intelligent variable water and fertilizer machine. [ABSTRACT FROM AUTHOR]

Warming climate has been a global concern. Methane is an important greenhouse gas. Double rice cropping system in Hunan province contributes a large proportion of the national rice production. In this study, we studied the effect of agricultural managements of rice on methane emissions from double cropping paddy fields in Hunan Province, China based on Meta-analysis method. Only studies designed as side-by-side paired field experiments were included in this study. Field management practices, treatments, and controls were described in detail in each study, and the location of the experiment was provided. If seasonal accumulative CH4 emission fluxes were not directly provided, these values were calculated by multiplying time and mean CH4 emissions by the measurement period. A total of 53 published peer-reviewed papers published before 2018were obtained by reference retrieval. From them, 840 groups of data were drawn. The management measures included crop rotation, symbiosis ecosystem, tillage, nitrogen fertilizer input, organic manure and residue retention. The control and treatment groups were fallow versus winter crops, paddy-rice system versus rice-duck and rice-fish systems, conventional versus no tillage, no fertilizer-N input versus fertilizer-N input, no manure input versus fertilizer-N and manure input, and fertilizer-N input versus residue retention. Natural log of response ratio was used as the effect size in the random effect meta-analysis. Results showed that CH4 emissions from both early and late rice accounted for 97.9% of annual CH4 emissions, and more CH4 emissions from late rice was observed than that for early rice. In the double rice cropping system, adding winter crops could significantly increase CH4 emissions from double rice season by 43.88% (P < 0.05) compared to winter fallow. Moreover, the increase in methane emissions from early rice was significantly higher than that from late rice. Symbiosis ecosystem of rice (i.e., with ducks or fishes) and adopting no-till significantly decreased CH4 emissions by 37.02% and 26.84% (P < 0.05), respectively. The decrease in the emission from early rice field was much higher than that from late rice field. As for yield-scaled emission, application of N fertilizer decreased yield-scaled CH4 emissions by 40.01% (P < 0.05) mainly due to the yields increased by 73.87% (P < 0.05). Additionally, organic fertilizer application and residue retention increased 68.11% and 71.80% (P < 0.05) of yield-scaled CH4 emissions without impacting the rice yield. The results suggested adopting symbiosis ecosystem rice production or no-till along with optimized N input is conducive to balancing rice yield and CH4 emissions from fields with double rice cropping system in Hunan province. [ABSTRACT FROM AUTHOR]

Warming climate has been a global concern. Methane is an important greenhouse gas. Double rice cropping system in Hunan province contributes a large proportion of the national rice production. In this study, we studied the effect of agricultural managements of rice on methane emissions from double cropping paddy fields in Hunan Province, China based on Meta-analysis method. Only studies designed as side-by-side paired field experiments were included in this study. Field management practices, treatments, and controls were described in detail in each study, and the location of the experiment was provided. If seasonal accumulative CH4 emission fluxes were not directly provided, these values were calculated by multiplying time and mean CH4 emissions by the measurement period. A total of 53 published peer-reviewed papers published before 2018were obtained by reference retrieval. From them, 840 groups of data were drawn. The management measures included crop rotation, symbiosis ecosystem, tillage, nitrogen fertilizer input, organic manure and residue retention. The control and treatment groups were fallow versus winter crops, paddy-rice system versus rice-duck and rice-fish systems, conventional versus no tillage, no fertilizer-N input versus fertilizer-N input, no manure input versus fertilizer-N and manure input, and fertilizer-N input versus residue retention. Natural log of response ratio was used as the effect size in the random effect meta-analysis. Results showed that CH4 emissions from both early and late rice accounted for 97.9% of annual CH4 emissions, and more CH4 emissions from late rice was observed than that for early rice. In the double rice cropping system, adding winter crops could significantly increase CH4 emissions from double rice season by 43.88% (P < 0.05) compared to winter fallow. Moreover, the increase in methane emissions from early rice was significantly higher than that from late rice. Symbiosis ecosystem of rice (i.e., with ducks or fishes) and adopting no-till significantly decreased CH4 emissions by 37.02% and 26.84% (P < 0.05), respectively. The decrease in the emission from early rice field was much higher than that from late rice field. As for yield-scaled emission, application of N fertilizer decreased yield-scaled CH4 emissions by 40.01% (P < 0.05) mainly due to the yields increased by 73.87% (P < 0.05). Additionally, organic fertilizer application and residue retention increased 68.11% and 71.80% (P < 0.05) of yield-scaled CH4 emissions without impacting the rice yield. The results suggested adopting symbiosis ecosystem rice production or no-till along with optimized N input is conducive to balancing rice yield and CH4 emissions from fields with double rice cropping system in Hunan province. [ABSTRACT FROM AUTHOR]

The evaluation of arable land quality is one of the important means to protect and manage arable land. In order to meet the needs of current arable land management work and protect the safety of national arable land resources, it is necessary to establish an arable land quality index system to evaluate the arable land quality. Based on the change of human demand for arable land resources, the components of arable land use system and the relationship between various components of arable land use system, this paper systematically expounded the theoretical framework of arable land quality evaluation，and the evaluation index system of arable land quality was established by the matching of different demand hierarchy characteristics of human and supply of arable land resources. The evaluation index system of arable land quality consisted of five dimensions: geology characteristics, soil traits, farming conditions, health status of arable land and biological characteristics of arable land. According to the different characteristics of each dimension of arable land quality, suitable evaluation methods were selected. The three dimensions of geology characteristics, soil traits and farming conditions were calculated by using the weighted additive. The health status of arable land is calculated by the “1+X” cumulative model; the biological characteristics of arable land were calculated by coefficients. Then, the quality of arable land for high yield and high efficiency demand was evaluated by the method of additive, and the quality of arable land for green health and sustainable development was evaluated by the method of revised. The quality of arable land in Daxing District of Beijing was evaluated by using multi-source and multi-scale data. The results showed that the evaluation results of arable land quality in Daxing District were divided into five grades at equal intervals of 20 points. The arable land quality index [80,100] was excellent, [60, 80) was good, [40, 60) was medium, [20, 40) was lower, and [0, 20) was poor. Under the conditions of high yield and high efficiency, the excellent area accounted for 88.27% of the total arable land, the good accounted for 11.73%. Under the condition of green health demand, the excellent accounted for 73.61% of the total arable land, and the good accounted for 26.39%. Under the conditions of sustainable development demand, the excellent accounted for 3.03% of the total arable land, and the good accounted for 52.30%, medium accounted for 40.39%, and lower accounted for 4.27%. From the perspective of space, the results of arable land quality evaluation of high yield, high efficiency, green health and sustainable development demand were all high in the east and low in the west. By comparing the results of arable land quality evaluation under different demand conditions, the area of arable land in excellent is decreasing, while the area of arable land in good, medium and lower is increasing. The health status of arable land and the biological characteristics of arable land have become important factors affecting the quality improvement of arable land. Research conclusions are that the evaluation index system of arable land quality based on sustainable development demand can provide effective support for the evaluation and management of arable land, and is more in line with the national quantity, quality and ecological management needs of arable land. [ABSTRACT FROM AUTHOR]

This paper was aimed to investigate the effects of organic fertilizer application (single application of organic fertilizer and organic-inorganic fertilizer combination) on the CO2 emission in farmland soil during crop growth period, under different climate types, fertilization measures, organic fertilizer types and experiment years in Northern China. Non-fertilizer and inorganic fertilizer application were used as control treatments. Based on the published data of relevant experiment and the Meta-analysis method, the quantitative effects on application of organic fertilizer and organic-inorganic fertilizer combination on CO2 emission in farmland soil were studied. A total of 534 measurements were obtained including 89 pairs of data from 21 literatures. The experiments lasted from 1980 to 2017. The effects were determined by effect size by Meta-analysis method. The important factors affecting CO2 emission were selected by finding out those with important values higher than 0.8. The results showed that the organic fertilizer application significantly generally increased the CO2 emission in farmland soil than the non-fertilizer and inorganic fertilizer application, with an increment of 50.6% and 36.3%, respectively. No publication bias was found because the fail-safe number was far higher than the critical values by the fail-safe method. There was not significantly different among regions (P>0.05). Under the application of organic fertilizer, the CO2 emission of farmland soil decreased successively in the following order: single application of organic fertilizer, organic-inorganic fertilizer combination, and combined application of inorganic fertilizer, organic fertilizer and slow-release fertilizer. Soil CO2 emission did not significantly increase under the combined application of organic fertilizer, inorganic fertilizer and slow-release fertilizer. Compared with non-fertilizer, cow manure, pig manure and commercial organic manure, chicken manure had the greatest positive effects on soil CO2 emission. Under the application of organic fertilizer, the CO2 emission of farmland soil in gray desert was relatively high. The CO2 emission of farmland soil was positively correlated with the annual average temperature and negatively correlated with the annual average precipitation. The annual average temperature and annual average precipitation could explain about 11%-16% and 10%-12% change in effect size of CO2 emission, respectively. From the perspective of environment, it was suggested to apply the combined application of inorganic fertilizer, organic fertilizer and slow-release fertilizer in Northern China. Meanwhile, the chicken manure should not be applied in large quantities and organic fertilizer should not be used in grey desert farmland. The results of this study can provide valuable information for the popularization and application of organic fertilizer replacing partial chemical fertilizer in Northern China. [ABSTRACT FROM AUTHOR]

Water-soluble liquid fertilizer containing humic acid is one of the important directions of liquid fertilizer development in the future. It not only has the high utilization efficiency and the abilities of water saving, environmental protection and increasing production, but also has the functions of enhancing plant resistance, promoting flower bud differentiation and development, and improving the quality of crops. According to the analysis, 90% of the nutrients of livestock and poultry manure and straw were preserved after biogas fermentation, and about 1/3 of nutrients entered biogas slurry. Using biogas liquid to develop liquid fertilizer could alleviate the problem of methane elimination and save water resources, besides producing high quality liquid fertilizer. In order to explore the feasible method for the development of water-soluble liquid fertilizer containing humic acid, in this paper, biogas slurry, formula fertilizer of cucumber, chelating agent, and stabilizer were used as the main raw materials, and the effects of different process parameters (amount of biogas slurry, amount of stabilizer, amount of chelating agent, reaction temperature and reaction time) on the performance of water-soluble liquid fertilizer containing humic acid were studied. The results showed that amount of biogas slurry, amount of chelating agent, amount of stabilizer, reaction temperature and reaction time had an important effect on the content of water insoluble substance in liquid fertilizer containing humic acid. In the case of the addition of certain amount of biogas solution, the impact importance of each factor was additive amount of stabilizer > reaction temperature > additive amount of chelating agent > reaction time. Adjusting amount of chelating agent, amount of stabilizer, reaction temperature and reaction time could reduce the concentration of water insoluble matter to a certain extent, and improve the total nutrient concentration in the liquid fertilizer. The excellent process parameters for preparing water-soluble liquid fertilizer were formula fertilizer of cucumber accounting for 39.6% of mixed material, biogas slurry 58%, stabilizer 0.4%, chelating agent 4%, reaction temperature of 40 °C, and reaction time of 1.5 h. Under such conditions, the content of total nutrient was 220.47 mg/L, humic acid was 33.25 mg/L and insoluble matter was 18.6 mg/L. The full utilization of biogas slurry was an important guarantee for the sustainable operation of biogas projects. From another point of view, under the premise of meeting the basic quality standard of liquid fertilizer, it was also of great practical significance to achieve maximum utilization of biogas slurry. The method not only realizes the full utilization of biogas slurry, but also has the advantages of high content of humic acid and nitrogen. It provides technical support for developing high quality water-soluble liquid fertilizer containing humic acid using biogas slurry. [ABSTRACT FROM AUTHOR]

Excessive amounts of fertilizers and irrigation water are used in agriculture, which will lead to some negative effects. Not only the resource utilization rate is reduced, but also the liquid nitrate content exceeds because of drainage, and the underground water source is polluted finally. Integration technology of water and fertilizers can improve the resource utilization, while the pollution of the surrounding natural environment can be also reduced. Automatic control and regulation of irrigation water and fertilizers integration have been implemented in the greenhouse production in Europe and North America, the resulting result is reasonable fertilizers and water application, and the control accuracy is higher. However, excessive irrigation and use of fertilizers still exist in China's greenhouse production. The result of this production mode is that the proportion of nutrient inputs is unreasonable and the nutrient is in serious loss due to excessive irrigation. It is necessary to conduct the thorough research on the integration technology of water and fertilizers to develop the regulation technology and equipment of water and fertilizers integration suitable for Chinese actual situation and with low cost. Preparation of nutrient solution is a process that fully mixes fertilizers and water and makes the nutrient solution reach the preseted value. There are 2 different modes in the mixed tank, including advection and ideal mixing, where all kinds of liquids are mixed, and the actual system can be considered as the combination of these 2 modes. Moreover, considering the time delay caused by the flow of liquid in the pipers, the process of the preparation of the nutrient solution can be simulated by using a first-order lag transfer function model. However, in order to achieve higher control accuracy the mixing tank should have sufficient space. Such nutrient solution's electric conductivity (EC) value will not change dramatically when injected into the liquid fertilizers, and therefore, the mixing tank should have a larger space. But it will bring a lot of other problems, for example, EC values' adjustment speed and flexibility will become worse. To resolve this conflict, a Venturi device is added to the mixing tank in this paper, so a virtual volume is added to the mixing tank, and the whole nutrient solution preparation system is converted to a second-order lag system. According to the theoretical analysis of the nutrient solution preparation system, a regulation and control equipment of water and fertilizers integration nutrient solution is designed in this paper. Besides the nutrient solution preparation function, the equipment also has irrigation control and environmental control functions, and the system structure is composed of computer, master control module, wireless transmission module, EC and pH measurement module and driver control module. The wireless transmission module includes 433 MHz wireless transmission, third generation (3G) wireless transmission and short message service (SMS) alarm; the drive control module is divided into nutrient solution ratio drive, environmental control drive and irrigation control drive; and EC and pH value of the nutrient solution are detected by the EC and pH measurement module. The control of nutrient solution is implemented in the following ways: first, the EC and pH values of the nutrient solution in mixing tank are detected online in realtime, and then the detection results are sent to the master control module through the RS-485 bus. The different value between computer's set value and current detection value is calculated by the master control module, and the nutrient solution ratio drive module is controlled by master control module according to the calculated results, so the injection ratios of fertilizer mother liquid are controlled by solenoid opening and closing. The nutrient solution adjustment process is executed finally. The regulation algorithm of nutrient solution is realized by the incremental PID (proportion, integration, differentiation) algorithm and a gain adaptive Smith predictor. The experimental results show that the system enters a stable stage in about 30 s and is infinitely close to the set value of the 2.0 mS/cm EC. This shows that the nutrient solution regulation equipment is not only faster, but also more accurate for the system response. [ABSTRACT FROM AUTHOR]

The implementation of biomass ash as a fertilizer is beneficial to the sustainable development of agriculture because it can return the elements taken by the plants from soil during the growth. Water solubility of biomass ash together with its elements is a vital property for the fertilizer's utilization. In this paper, the effects of ash forming temperature on the water solubility of biomass ash and its elements were investigated experimentally. Three typical types of agro-residues in China, i.e. wheat straw, corn stover and rice husk, were chosen for investigation. Materials were collected and the corresponding proximate and elemental analyses were performed. In preparation process, wheat straw and corn stover were milled into powder with the particle size of less than 1 mm. Ashes were prepared in a muffle furnace at different ash forming temperatures in the scope from 400 to 800 °C with the temperature interval of 50 °C. About 4-5 g of each sample powder and rice husk were put in the crucibles, heated from ambient temperature to ash forming temperature, and then kept at the ash forming temperature for 4 hours in the muffle furnace. After the temperature of the furnace dropped to less than 200 C, the ashes were taken out to the cabinet dryer, cooled to the ambient temperature, and then weighted and sealed in the sample bag for further measurements. It showed that ash contents of wheat straw, corn stover and rice husk decreased significantly with the increase of ash forming temperature. They decreased from 9.8%, 10.9% and 18.4% at 400 C to 6.9%, 8.7% and 16.8% at 800 C respectively. After the preparation of all the ash, two types of measurements were performed. The first was the water solubility measurement of the ashes according to the standard of GB8307-2002. Total ash of about 0.2-0.3 g was put in a beaker of 50 ml and about 25 ml distilled water was added in it. The mixture was heated and boiled for 2 min and then the solution was filtered through a quantitative filter paper. The filter residue was washed for several times using another 25 ml distilled water. After the burning of the filter residue, the insoluble ash was weighed and sealed in a sample bag. Results showed that the ash's water solubility of corn stover and wheat straw was much higher than that of rice husk. All of them were significantly affected by the ash forming temperature. They decreased from 48%, 35% and 12% to 12%, 8% and 0, respectively. The second was the water solubility measurement of the elements. This was based on the X-ray Fluorescence Spectrometer (XRF) tests of the original ash and water-insoluble ash using ZSX100e. The sample ash was pressed into a thin disc with the diameter of 30 mm. Then it was measured in vacuum with full scan mode by XRF. The data of measurement was processed using SQX (semi-quantitative nonstandard analysis program) and the mass concentrations of the elements were obtained. Result showed that there were respectively 11, 10 and 4 elements whose concentrations were more than 1% in the ash of wheat straw, corn stover and rice husk. And oxygen (O), silicon (Si), potassium (K), and calcium (Ca) were the major elements in all ashes, while chloride (Cl) was rich in stalks. The Cl concentration in the original ash decreased significantly with the increase of ash forming temperature. The water solubility of the elements in ash was calculated via two methods, i.e. mass conservation method and silicon trace method. Result showed that the major dissolved elements in ash were K, Cl and S (sulfur). The solubility of K and Cl decreased with the increases of ash forming temperature and the solubility of S was almost not affected by temperature. The experimental results can be used as the reference for environmental assessment and optimization of thermo-chemical process of biomass. And the method can be expanded to determine the recycling characteristics of other types of biomass ash. [ABSTRACT FROM AUTHOR]

In order to evaluate the effects of different levels of water and fertilizer on yield and quality of jujube under drip irrigation that changed from flooding, a field experiment was conducted to find the optimal irrigation and fertilizer combination with the higher water and fertilizer use efficiency. The statistical analysis methods of multivariate quadratic regression and normalization were used in this paper. The local jujube variety of Jun-jujube(9 years) was chosen for test material. The conventional flooding irrigation with irrigation and fertilizer quota as 1100 mm and 900 kg/hm2 (N:P:K = 2:1:1.5) respectively was selected as the control group (CK). In this study, the irrigation and fertilizer treatments were designed with a two-factor and three-level quadratic orthogonal rotated composite experiment. The irrigation amount treatments in three levels was W1 (45% CK), W2 (65% CK), W3 (85% CK), and fertilizer treatments in three levels was F1 (45% CK), F2 (65% CK), F3 (85% CK), respectively. The results showed that the effects of irrigation on soil nutrients (total N, available P, available K) and irrigation water use efficiency (iWUE) reached significant level (P < 0.05) in the jujube growth period of flowering and swelling. The effects of fertilization on soil nutrient and fertilizer partial productivity (PFP) reached significant level (P < 0.05) in the period of jujube flowering and swelling. However, the interaction effects of irrigation and fertilization on soil nutrients, yield and jujube quality indicators reached significant level (P < 0.05) at the whole stages of growth. The soil nutrients in 0-40 cm layer were higher under flooding irrigation than that under drip irrigation. There was a nutrient transition layer at depth of 40~60 cm. while the soil nutrients were significantly lower under flooding irrigation than that of drip irrigation in the soil layer of 60-100 cm. The W2F3 treatment had the better soil nutrient environment in the root zone for the different irrigation and fertilizer treatments. Comparing with flooding irrigation, the maximum soil nutrients value under the drip irrigation were W2F3 treatment generally. The drip irrigation treatment of W2F3 had the highest yield, but there was no significant difference with CK (P > 0.05). The maximum value of iWUE and PFP was W1F3 and W3F1 treatment, respectively. The maximum value of total sugar, vitamin C and total acid was in W2F2, W3F3 and W3F1 treatment, respectively. W3F2 treatment and CK had significant difference (P < 0.05) in the net income, and increased by 1.95% comparing with the CK. The mathematic model of water-fertilizer investment and jujube indicators was established through multiple quadratic regression analysis, and the suitable investment of water and fertilizer obtained from the mathematic model were ranged in 651~806 mm and 708~806 kg/hm2, respectively, where N (311-345 kg/hm2), P2O5 (156-178 kg/hm2), K2O (233-267 kg/hm2). The study can provide a reference for the optimal irrigation and fertilization management of jujube cultivation in the southern Xinjiang sandy area with drip irrigation. [ABSTRACT FROM AUTHOR]

It is very important for the sustainable agriculture development and environmental protection to determine the environmental safety threshold of fertilizer in China. Models of fertilization environmental safety threshold were setup to study the spatio-temporal changes, reasonability of fertilization intensity and its environmental safety threshold. The results showed that: 1) the fertilizer application rate had been increasing since 1980 in China. The application rate in 2014 was as about 5 times as that in 1980, the fertilizer intensity in 2014 was as nearly 4 times as that in 1980, and the efficiency of fertilization decreased by 50% from 1980 to 2014. The proportion of N : P : K was from 1 : 0.3 : 0.05 in 1980 to 1 : 0.5 : 0.43 in 2014. Intensities of N, P and K fertilizer application rate started to exceed the environmental safety thresholds in 1988, 2000, 2009, respectively. The gaps had been increasing ever since; 2) in China, the areas with low intensity of fertilization included Qinghai, Xizang, Gansu, Sichuan, Guizhou, Jiangxi and Heilongjiang, mainly distributed in the west part of China. The areas with medium intensity of fertilization included Chongqing and some others. Hainan, Henan, Beijing and Tianjin belonged to those with very high intensity of fertilization. Xinjiang and some others belonged to the high intensity fertilization area. The high and very high intensity fertilization areas were located at North China Plain and south-east coastal areas; 3) There were 3 types of N fertilizer environmental safety threshold regions: low threshold area (≤125 kg/hm2), medium Nitrogen threshold region (125-165 kg/hm2), and high Nitrogen threshold region (>165 kg/hm2). More than 60% of the studied areas in China belonged to the medium environmental safety threshold area; Qinghai, Gansu, Shannxi, Shanxi, Yunnan and Guizhou belonged to the low threshold area; Jilin, Liaoning, Shandong, Jiangsu and Xinjiang belonged to the high threshold area. The distributions of fertilization environmental safety thresholds for P and K were same as Nitrogen threshold regions; 4) At average, the fertilization intensity in 2014 was as high as 1.2 times the environmental safety threshold, while the highest fertilization intensity in Shannxi was twice higher than its safety threshold. But there were still some provinces that had lower fertilization intensity than their fertilization environmental safety threshold, which had not met the need for fertilizers. Although N and P inputting were beyond their thresholds in many provinces, the deficient inputting of K was popular in most provinces. So each province should take different measures of fertilization to deal with the relationship between food production and environmental protection. The model of fertilization environmental safety threshold in this paper showed that the threshold of fertilization is affected by the local natural, economic and cropland management condition, which is related with local crops' production and environmental quality. It would play important roles in the eco-agricultural construction in China. [ABSTRACT FROM AUTHOR]

Carbon trading is the market mechanism to reduce global greenhouse gas (GHG) emissions. Soil testing and formulated fertilization play an important role in reducing the fertilizer application and GHG emissions in intensive agricultural production area of China. In this paper, the methodology of upland GHG emission reduction in soil testing and formulated fertilization was proposed according to the basic process of carbon trade methodology. Huantai County, Shandong Province was chosen for the case study of tradable carbon calculation. The main conclusions were as follows: 1) Boundary of the project included the geolocation of upland crops and the production process of chemical fertilizers. Baseline of the project was CO2 emission in chemical fertilizer production and N2O emission in upland crop planting without soil testing and formulated fertilization, while the project activities were GHG emissions in above processes under soil testing and formulated fertilization. 2) In Huantai County, too much nitrogen and phosphorus fertilizer were added to the cropland, while potassium fertilizer was suitable. The average application amounts of nitrogen, phosphorus and potassium in wheat-corn rotation system were 515.1, 289.5 and 145.7 kg/hm2, respectively. The investigation of nitrogen fertilizer production enterprises showed that the average CO2 emission for the production of 1 t urea was 2.23 t (CO2 equivalent, the same as below). 3) The tradable carbon from soil testing and formulated fertilization was 26 485.8 t, and the farmland emission reduction, nitrogen fertilizer production reduction and phosphatic fertilizer production reduction accounted for 35.3%, 58.3% and 6.8%, respectively. Potassium production increased by 110 t emission, accounting for -0.4%. The situation was different in every town of the county because of the different crop area and fertilization. GHG reduction for Suozhen Town and Qifeng Town was 4848.6 and 6 180.3 t, respectively. The main reason was that too much fertilizer was used in these 2 towns. GHG reduction in Tianzhuang, Jingjia, Chenzhuang, Xincheng, Zhoujia and Guoli was between 1 700 and 2 300 t. GHG reduction in Xingjia, Maqiao and Tangshan was lower than 1 700 t, mainly because less fertilizer was used in these towns. 4) According to the carbon price of Shenzhen carbon trading market in March 2016, the emission reduction projects of soil testing and formulated fertilization in Huantai County could reach 12.86 million yuan, with 1.286 million yuan every year, which met the project requirement of small carbon trade. 5) The carbon trading methodology system that adopted the Denitrification and Decomposition (DNDC) model as the main measurement tool could achieve the carbon emission reduction calculation. The study has great significance to the implementation of GHG carbon emission reduction project from soil testing and formulated fertilization. [ABSTRACT FROM AUTHOR]

Soil alkalization is one of major environmental problems which adversely affect growth and development of plant and crop yield in agricultural production all over the world. Effective measures should be taken to reduce the impact of alkaline stress on plant growth. Urea phosphate is a new-type compound fertilizer in the drip-irrigation. It can generate acid after hydrolysis, but it is unclear if it can improve soil pH value and plant growth after applying to alkaline soil at present. Therefore, this study was conducted to test the effects of urea phosphate solution on soil pH value, plant growth and physiological characteristics of large-leaf spinach. The alkaline stress was simulated by irrigating 5 mL/d solution which was a mixture of 300 mmol/L NaHCO3 solution and 300 mmol/L Na2CO3 solution at 1:1 molar ratio for 6 d in a greenhouse. Four treatments were set in a random complete block design in this paper, including CK (Non-alkali stress), AS treatment (adding 5 mL deionized water after alkali-stress), AS+FT treatment (adding 5 ml inorganic fertilizer solution after alkali-stress which was mixed with diammonium phosphate and urea solution and had a concentration equal with urea phosphate solution) and AS+UP treatment (adding 5 ml urea phosphate solution after alkali-stress). The results showed that the soil pH value was significantly increased by 44.19% after alkali-stress, but it were significantly decreased by 2.69 and 0.86 when applying urea phosphate solution and inorganic fertilizer solution to soil 6 days after alkaline stress, and urea phosphate solution had better effect than inorganic fertilizer solution on improving soil pH value. Compared to AS treatment, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities in AS+UP treatment were significantly increased by 6.42%, 42.08% and 55.13%, respectively, malondiadehyde (MDA) content was significantly reduced by 10.62% and then the extent of membrane lipid was obvious alleviated. Meanwhile, photosynthetic pigment content was greatly improved after applying urea phosphate solution. Chlorophyll a, chlorophyll b and carotenoid concentrations of AS+UP treatment were increased by 22.36%, 32.06% and 10.88%, respectively. Improvement effect on spinach seedlings growth in AS+UP treatment was superior to AS treatment, and plant height, whole leaf area and dry substance of spinach of AS+UP treatment were respectively 23.55%, 21.03% and 33.84% higher than AS treatment. However, the seedling growth in AS+FT treatment was inhibited and physiological characteristics of spinach leaves were decreased. Compared to AS treatment, SOD, POD and CAT activities in AS+FT treatment were reduced by 15.33%, 29.06% and 51.15%, respectively, and its MDA content was higher than that of AS treatment, so chlorophyll a, chlorophyll b and carotenoid contents were decreased by 19.84%, 37.15% and 14.15%, respectively. Moreover, leaf area, dry matter weight and root length were also respectively 26.47%, 26.16% and 1.65% lower than AS+UP treatment. This research indicates that urea phosphate solution has positive effects on improving soil condition and enzyme activity under alkaline stress. Therefore, it can be promoted as a kind of soil amendment to reduce soil pH value in alkaline soil, enhance the ability to adapt to alkali stress and ensure the normal growth and development of crop plants, and it may be a valid method to increase land use efficiency and mitigate the pressure of land demand. [ABSTRACT FROM AUTHOR]

With the popularity of understanding of pollution-free agricultural products by the public, government pays much attention to the safe application of organic fertilizer during the agricultural production process. Manure is not only the main raw material of organic fertilizer, but also one of the important factors affecting the quality of agricultural products. Due to the intensive and large-scale of livestock farming rapid development, some heavy metals such as Cu, Zn, As, Cr, Pb are widely used in feed additives. The biological potency of these trace elements is low, and with the use of animal manure into the environment, brings potential environmental risks and hazards to human health. In order to strengthen the source control of heavy metal, and further form the heavy metal resistance control system for organic fertilizer of agricultural products, in this paper, the heavy metal content in livestock and poultry feed was sampled for investigation and analysis. The results showed that the mainly exceeded elements of heavy metal in the livestock were Cu, Zn. Heavy metals Pb, Cr, As followed, and Cd, Ni, Hg were not exceeded. The exceedance of these elements in pig manure and broile manure were the most serious for all kinds of animal manure, beef cattle manure and egg chicken manure followed, and the cow dung was not exceeded. The value of the exceeded rate of Cu, Zn for pig manure and broile manure were up to 100% and 91.67%, respectively. The mainly pollutants for broile were Cr, Cu, Zn, and the value of exceeded rate were 50%, 66.67%, and 50%, respectively, but the egg chicken manure only had Cu exceeded, exceeding the rate of 11.11%. Different livestock feed exceedances of heavy metals in pig feed and beef cattle feed werethe most serious, and broile feed and cow feed followed. According to the Ministry of Agriculture's 1224 announcement for the Cu, Zn standard, Cu and Zn in pig feed exceeded the rate of 66.67% and 80.00% respectively, and broile feed Zn exceeded 62.50%; According to the feed hygiene standards for Cr, Pb, heavy metals Cr and Pb in beef cattle exceeded 83.33% and 66.67%, Cr in cow feed exceeded 60%, Pb in egg chicken feed exceeded 53.85%, and Cd in different animal feeds were not exceeded. The content of heavy metals Cd, Cr, Cu, Zn in animal manure showed a significant positive correlation with livestock feed (P<0.01), and the content of Pb in animal manure showed a significant correlation with livestock feed (P<0.05). The research helps to grasp the North China heavy metal pollution status in feed-animal manure, revealing the problem for heavy metals exceeded in manure and organic fertilizer which should be controlled from the source. This research to further reduce heavy metal pollution in the region and to ensure the quality and safety of agricultural production has an important significance. [ABSTRACT FROM AUTHOR]

In China, the freeze-thawing phenomenon occurs in the northeastern region, which happens in autumn, winter and early spring and can affect the structure as well as physical and chemical properties of the black soil. The concentrations and speciation of nutrition elements (nitrogen and phosphor) in black soil are also influenced by the freeze-thawing, which may have effects on the fertility of the soil or even result in eutrophication. In order to find out the change of nitrogen and phosphor concentrations and availability in black soil with various levels of fertilizers under freeze-thawing condition, a simulation freeze-thawing experiment was proposed in this paper. Various levels of inorganic nitrogen and phosphor fertilizers as well as organic fertilizer were applied in 10 maize plots based on the results of investigation on agricultural production in Heilongjiang Province and the specific circumstance of the present experiment. Then the black soil samples were collected from the 10 plots and put through simulative freeze-thawing cycles in the lab. After each cycle, the parameters of the soil samples were analyzed, including the soil properties (moisture contents, mass fraction of organic matters) and mass fractions of total nitrogen, available nitrogen, total phosphor and available phosphor. It was shown that freeze-thawing process could increase the moisture contents of soil samples for all the 10 treatments (P<0.05). And under the freeze-thawing condition, the inorganic and organic fertilizers could improve the water holding capacity, resulting in higher moisture contents than the unfertilized soil (P<0.05). The mass fraction of organic matters in soil samples for all the 10 treatments significantly decreased after 5 freeze-thawing cycles, and the highest reduction rate after 5 cycles was obtained in the sample with only organic fertilizer (29.7%, P<0.05). For the samples with inorganic fertilizers, concentrations of total nitrogen decreased significantly after 5 freeze-thawing cycles (P<0.05), indicating that freeze-thawing process could result in the loss of total nitrogen in black soil. The reduction rate of total nitrogen concentration after 5 freeze-thawing cycles was positively related to the quantity of inorganic nitrogen fertilizer (r=0.9899) when the level of inorganic phosphor fertilizer was constant. When organic fertilizer was applied, the total nitrogen concentrations in soil samples after 5 freeze-thawing cycles changed insignificantly, therefore the loss of total nitrogen could be inhibited. For all the samples except the one where inorganic nitrogen fertilizer level was the largest, concentrations of available nitrogen increased significantly after 5 freeze-thawing cycles (P<0.05), while the application of inorganic nitrogen and phosphor fertilizers could inhibit the increase of available nitrogen concentration. The increasing rate of available nitrogen concentration after 5 freeze-thawing cycles was negatively related to the quantity of inorganic nitrogen fertilizer (r=-0.9675) when the level of inorganic phosphor fertilizer was constant. When the organic fertilizer was applied in the soil samples, the increasing rates of available nitrogen mass fraction were the highest among all the treatment (20.8% and 23.6%, P<0.05), indicating that application of organic fertilizer could improve the availability of nitrogen in black soil. The concentrations of total phosphor in samples for all the treatments changed insignificantly after the freeze-thawing cycles. For all the 10 treatments, the concentrations of available phosphor in soil samples increased after 5 freeze-thawing cycles (P<0.05). The application of either inorganic or organic fertilizer in the experiment could make the increasing rate higher, and the highest occurred when organic fertilizer were applied (23.4% and 27.1%, P<0.05), suggesting that the availability of phosphor in black soil could be higher when organic fertilizer was applied. In conclusion, during the agricultural practice of black soil in cold regions under freeze-thawing condition, the quantity of organic fertilizer applied should increase appropriately in order to inhibit the loss of total nitrogen, as well as to improve the availability of nitrogen and phosphor, so as to maintain the fertility of black soil and lower the risk of eutrophication. [ABSTRACT FROM AUTHOR]

Songnen plain is the main grain strategy reserve area of China, and it is also one of the three largest soda saline-alkali soil regions in the world. Soil salinization severely restricts the sustainable development of agriculture and the improvement of people's living standards. The land consolidation major projects officially launched in the west of Jilin Province in 2007 provides an effective way for comprehensive controlling salinity land. In the process of land consolidation, one of the most important problems need to be addressed was how to combine land consolidation with soil improvement to realize the purpose of increasing cultivated land areas and improving salinity soil. In order to study the Western Songnen Plain land consolidation effect on improving salinity soil, this paper took the land consolidation project in Zhenlai county of Jilin Province as study area, selected the original cultivated land, saline-alkali land and newly-added cultivated land as plots, adopted the methods of classical statistical analysis and canonical correspondence analysis to comparative study the differences of soil physical and chemical properties and soil ionic composition of different plots. And then we put forward related suggestions for land consolidation and improving salinity soil. The results showed that, in 0-20 and >20-40 cm soil layer, soil electrical conductivity of newly-added cultivated land was significantly decreased by 44.9% and 37.0% than saline-alkali land (P<0.05), but significantly higher than original cultivated land by 35.7% and 58.6%. The total actions and total anions of newly-added cultivated land were significantly lower than saline-alkali land (P<0.05). The exchange sodium percentage of saline-alkali land was around 38% and pH value was close to 10.0, that was classified to severe salinity soil. While the newly-added cultivated land soil exchange sodium percentage was 18.0% and 21.6%, and soil pH value was less than 9.0, that was classified to moderate salinity soil and close to the original cultivated land. Newly-added cultivated soil organic matter was higher than saline-alkali land by 33.4% and 61.3% significantly (P<0.05), but it was significantly lower than original cultivated 21.5% in 0-20 cm soil layer. Newly-added cultivated soil cation exchange capacity was increased by 16.7% and 25.1% than saline-alkali land (P>0.05), and it's slightly higher than original cultivated land. Canonical correspondence analysis results showed that soil physical and chemical properties and ionic composition had significant correlation with plot type distribution. Plot type changed from saline-alkali land to newly-added cultivated land was the process of soil salinization indices decreasing and fertility indices rising in the level of soil physical and chemical properties, and also the process of bicarbonate ion, carbonate ion and sodium ion content reduction in the level of soil ionic composition. Overall, the land consolidation project in Western Songnen Plain could improve salinity soil effectively, but the soil quality of newly-added cultivated land is still lower than the original cultivated land. Therefore, we suggest to improve salinity soil better through improvement of irrigation and drainage system, reasonable land leveling measure and scientific farming. [ABSTRACT FROM AUTHOR]

Deep fertilizing is a high efficiency fertilization method in rice fields. In order to realize deep fertilizing, according to the requirement of rice planting, a synchronous side deep fertilizing technique is developed on the base of a precision rice hill-drop drilling technique. By ditching, ridging, deep fertilizing, and seeding joint operations, the fertilizing ditch openers prescribe fertilizing ditches, and the fertilizer apparatus puts fertilizers into the fertilizing ditches which are between two seeding ditches, to provide fertility of the necessary growth for rice in the two seeding ditches. At the same time, the fertilizing ditches are covered by the skateboard. After covering, fertilizers can reduce the loss due to volatilization, denitrification, and leaching. And then the seeding ditch openers prescribe seeding ditches, and the seed-falling devices take rice into the seeding ditches, at the same time the water ditch openers prescribe water ditches, and the water in the water ditches will be provided for the rice in the seeding ditches. In order to explore the distribution of the depth of deep fertilizing and fertilizer in different soil layers, this paper investigated the special distribution of the rice root system in different planting patterns and rice varieties. The 80% rice root is in a 0-10 cm soil layer. Technical parameters for synchronous side deep fertilizing were studied based on the special distribution of the rice root system in that soil layer (0-10 cm). The optimum fertilization depth was identified as 10 cm. And according to the special distribution of the rice root in the 0-5 and 5-10 cm soil layers, fertilization distribution for the rice varieties of 'Peizataifeng' and 'Yuxiangyouzhan' in the 0-5 cm and 5-10 cm soil layers was researched. The field experiment results showed that the precision rice hill-drop drilling machine with synchronous side deep fertilizing developed in SCAU meets the requirements of the synchronous side deep fertilizing technique, which can be used as the implementation of a synchronous side deep fertilizing technique with precision rice hill-drop drilling. The field experiment results in rice production indicated that the technique can increase the yield and reduce the cost. Compared with the artificial fertilizing on the same fertilizing level, the higher effective panicle, grains per panicle, and seed setting rate were achieved with the synchronous side deep fertilizing technique. The rice yield increased by 418.5-957 kg/hm2 with an improvement of 5.86%-13.41%. The research results could provide the references for the design synchronous side deep fertilizing machine. [ABSTRACT FROM AUTHOR]

The key problems for realizing precision agriculture include integrating heterogeneous and multi-source agricultural information, developing localization agricultural resources, and providing personalized and active information services for individual farmers. In this paper, we present an approach to precision farming in citrus production management by using semantic technology. In our work, the first step was to transfer the expert knowledge existing in technical reports and books into the citrus fertilization and irrigation ontology that could be understood and directly computed by computer systems. By developing the ontology based on the semantic technology such as the resource framework description triples graph, heterogeneous and multi-source information was integrated into computable localization resources. We described how knowledge in the form of texts, pictures, and tables were encoded into resource description framework triples respectively. In addition, we also discussed how to establish properties, which is a difficulty in ontology development. Our ontology development process was supported by a set of professional tools: TopBraid Composer, the world's most powerful modeling environment, and Gruff, a graphical triple-store browser. We created 31 properties in total and used another five standard properties from the Semantic Web standards. As our aim for building the ontology was to support the decision making for citrus production management, our citrus ontology was not just taxonomy for the citrus management knowledge compared to the existing agricultural ontologies. Then we developed a personalized decision support system for citrus fertilization and irrigation management, based on the ontology. Different from the existing agricultural information services, our system can actively provide personalized production management instructions for individual farmers via multiple terminal devices, including mobile phones and Web browsers. The demo application was implemented using JSP/Servlet. The citrus ontology was loaded into a high performance semantic database system: AllegroGraph 4.10. Applications accessed semantic data via the Java Sesame application programming interface. The real time data from orchards, such as soil sensor records, were stored in relational databases. The demo decision support system had three major functionalities: fertilization management, physiological disease control, and irrigation management. The fertilization management functionality helps farmers fertilize their citrus orchards in the four major lifecycles of citrus. The physiological disease control functionality helps farmers react to nutrient deficiency or excess. The irrigation management functionality provides a real time monitoring and instructions for orchards watering and drainage. We have conducted system validation for the three modules. By testing the fertilization module with 216 data, it generated correct outputs according to the 5 factors: age, lifecycle, soil type, terrain and yield. The physiological disease control module was validated by 100 data, which covered 12 nutrients excess and deficiency diseases. The results showed that the system could correctly detect diseases. The drainage and irrigation monitor module was tested using historical soil moisture data, and the results showed that the system could correctly alarm for abnormal conditions. Finally, the system performance was tested with 361 inputs. The average response time is within 0.23 s for Web browser application and 0.58 for mobile application. This research provides a feasible solution to the problems of precision agriculture. We have demonstrated how expert knowledge in different forms can be transformed into a computable localization resource -- semantic ontology. This kind of transformation solves the problem of integrating and modeling heterogeneous and multi-source agricultural data. In addition, the semantic ontology and triple-store have a good scalability that can be continuously extended during the interaction with farmers and experts. The developed demo system can provide active and personalized instructions for individual farmers to guide them in orchard management with expert knowledge. Our research puts forward a solution to intelligent agriculture. Although this research focused on Chongqing citrus farming, the presented results can be applied to other crops and regions in China. [ABSTRACT FROM AUTHOR]

Limited cultivated land has become one of the major restrictions for China's social and economic development, and how to use it intensively is the focus of the Chinese government and research scholars. Based on emergy theory and methods, the cultivated land use intensity (I) was composed of production factors intensity (P) and multiples the multiple cropping index (M). On this basis, the paper analyzed the temporal and spatial change law of all the five production factor intensities, which are farm machinery, fertilizer, pesticide, agricultural film and labor, and the multiple cropping index in China from 1990 to 2011. The results showed: Firstly, during the past 22 years, the farm machinery intensity, fertilizer intensity, pesticide intensity, and agricultural film intensity were all in a linear growth trend, and their annual growth rates were 6.59%, 2.89%, 3.88% and 7.42% respectively; while the labor intensity was in a linear decreasing trend, and its decreasing rate was 5.10 percent. In 1996, the possession of industrial supplementary energy intensity, including farm machinery, fertilizer, pesticide, and agricultural film, in the total production factors intensity first exceeded 50 percent, which meant that China had entered the modern agriculture stage in the middle of 1990s. During the study period, multiple cropping index was also in a linear growth, and the annual growth rate is 0.79%; its total increasing rate was 0.1794 in the past 22 years, and was the major driving force of the increase of land use intensity. Secondly, in 1996, the provinces with high labor intensity and low development of modern agriculture were mainly located in the western part of China, and the typical characteristics of these provinces were that they were all rated with a relatively low level of social and economic development; While in the provinces with high development of economic levels and a good industrial foundation, the labor intensity was low and development of modern agriculture was high. From 1996 to 2008, most provinces in the western part of China and some of the coastal provinces in the eastern part of China, labor intensity decreased a lot; while in the provinces with high economic development and the provinces with more land and fewer persons, labor intensity decreased only a little. In the provinces with high economic development in the eastern coastal part of China and some major grain producing areas, industrial supplementary energy intensity increased a lot; In the provinces with high development of modern agriculture, industrial supplementary energy intensity increased only a little. Thirdly, from 1996 to 2008, in the major rice producing areas in southern part of China, the multiple cropping index decreased a lot, which was the major reason that contributed to the decreasing of their land use intensity; In most provinces in the northern part of China, the multiple cropping index increased a lot, which was the major reason that improved their land use intensity. [ABSTRACT FROM AUTHOR]