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Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biochar is one of the most important soil amendment materials. An ever increasingly prominent role can be found in carbon sequestration and greenhouse gas, especially in the methane (CH4) and nitrous oxide (N2O) mitigation potential. Among them, humic acid amendments to the cropland have dominated the C, N cycling and yield. In this study, a systematic investigation was implemented to clarify the influencing mechanisms of the biochar and humic after one year of application on global warming potential (GWP) and greenhouse gas intensity (GHGI) of CH4 and N2O emissions under a rice-wheat rotation system. A field experiment was designed with the double factors randomized block design in an acidic paddy of Hangzhou, Zhejiang Province, China. Six treatments were conducted in 2020 before the rice seedlings were transplanted as control without biochar or humic acid (B0F0), 0.6 t/hm² humic acid without biochar (B0F1), 1.2 t/hm² humic acid without biochar (B0F2), 20 t/hm² biochar without humic acid (B1F0), 0.6 t/hm² humic acid with 20 t/hm² biochar (B1F1), and 1.2 t/hm² humic acid with 20 t/hm² biochar (B1F2). The CH4 and N2O emissions were then measured in the different treatments one year later in 2021-2022. An evaluation was also performed on the one-year field-aged biochar and humic acid amendment in a typical rice-wheat rotation system. The results showed that after application of one year 1) the biochar increased the soil organic carbon (SOC) content both in rice and wheat season; Humic acid significantly increased the SOC content in the rice season, whereas, there was no significant effect on the SOC in the wheat season. Meanwhile, there was no effect on rice yield in the application of biochar alone, humic acid alone and application of biochar and humic acid together, compared with the B0F0 treatment. The application of biochar and humic acid together significantly increased the wheat yield by 1.0%-5.0%. 2) The application of biochar and humic acid addition reduced the cumulative CH4 emissions by 11.1%, 21.8%-25.8% and 24.7%-34.1%, compared with the B0F0 treatment, but the cumulative N2O emissions were promoted by 33.3%, 10.0%-30.1% and 7.2%-23.7%, respectively. 3) The estimated gross GWP of CH4 plus N2O among the treatments was significantly reduced by the application of biochar and humic acid. The reason was attributed to the reduction of cumulative CH4 emissions. In addition, the biochar and humic acid addition significantly reduced the GHGI during the whole rice and wheat season, in terms of greenhouse gas emissions and yield. The application of biochar and humic acid reduced the GHGI by 10.2%, 17.3%-20.2%, and 27.2%-36.2%, respectively, compared with the B0F0 treatment. The lowest GWP and GHGI were achieved in the B1F1 treatment (biochar and humic acid were added at the rate of 20 and 0.6 t/hm², respectively) among all the treatments. Consequently, outstanding performance can be expected in biochar and humic acid after the application of one year of the GHGs mitigation and carbon sequestration. A beneficial measure can also be utilized to improve the grain yields with less greenhouse gas emission in the rice-wheat rotation system. [ABSTRACT FROM AUTHOR]

Food waste is ever increasing in rural areas in recent years, particularly with the rapid economic development and population growth. If disposed of improperly, severe pollution can pose a great threat to the rural living environment. Fortunately, aerobic composting has been widely applied for food waste treatment, due to the high harmlessness and resource utilization rate. It is worth noting that food waste with high salinity can limit the application of aerobic composting. Among them, humification is one of the most important processes in the application of compost. However, only a few studies focused on the effect of salt content on aerobic compost humification. It is still lacking in the influencing mechanisms from the perspective of microbial community structure evolution. Taking food waste as the main raw material, and the maize stover as an auxiliary material, this study aims to explore the influences of salt content on the basic maturity index, organic matter composition, and dynamic change of humus substances during the composting process. The succession of microbial community was combined with the correlation statistical analysis, in order to reveal the microbial action about the effect of salt content on the mature process of food waste aerobic composting. Specifically, the food waste and maize stover were mixed well at the ratio of 4:1, where the initial moisture content was adjusted to about 63%. A composting experiment was carried out in the 60 L composting reactors for 45 days. A total of four experimental treatments were set with the addition of 0%, 0.5%, 1.0%, and 1.5% salt. Among them, the treatment without salt was the control group. The results showed that the temperature, C/N, and organic matter composition of four treatments fully met the requirements of maturity during aerobic composting. However, the salt addition greatly increased the electrical conductivity of the reactor. Particularly, the thermophilic period was shortened to 13 days at the proportion of salt addition of 1.5%. But, the seed growth was inhibited with the seed germination index reducing to 65.5%. Compared with the control treatment without salt, the degradation rate of organic matter was reduced by 6.5%, indicating the restricted humification process. The high throughput sequencing showed that the addition of 1.5% salt inhibited the activities of Thermobifida, Saccharomonospora, Aspergillus, and Trichosporon. In addition, a correlation analysis showed that the high salinity reduced the biodegradation of organic matter, such as total sugar and lignocellulose, thereby limiting the subsequent formation of humus substances. Thus, restricted improvement was found in the humification effect during food waste and maize stover composting. These findings can provide theoretical support for salt regulation in the application of aerobic composting in food wastes. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A large number of cow dung can cause the severe environmental pollution if not properly disposed of, particularly for the large-scale intensive cattle farm. A clean and sustainable treatment, composting has been commonly applied to the organic wastes in recent years. However, the traditional composting process cannot fully meet the requirement of industrial production in modern livestock farming, due to the low cellulose degradation and product maturity. Previous studies show that Aspergillus niger can be utilized to accelerate the degradation of organic matter for better composting maturity. However, a systematic understanding is still lacking on the application of Aspergillus niger on cow dung composting at present. In this study, a systematic optimization was performed on the fermentation process in composting using a combination of fluorescence excitation–emission matrix (EEM) spectroscopy and fluorescence regional integration (FRI). An attempt was also made to clarify the effects of Aspergillus niger on cow manure compost maturity and cellulose degradation. Cow manure was mixed to the moisture content of about 60%, with the wheat straw as an auxiliary material. With no Aspergillus niger as the control treatment, 1%, 2%, and 3% Aspergillus niger were added for the aerobic composting. A composting experiment was carried out in 60L composting reactors for 40 days. The compost maturity was evaluated to determine the maturity index, nutrient content, humus composition, and cellulose degradation. The results showed that the inoculation of 2% Aspergillus niger rapidly increased the temperature, where the thermophilic phase appeared 1 day ahead of time, compared with the control treatment. The content of humic acid increased by 49.94 g/kg, but the fulvic acid decreased by 37.51 g/kg, compared with the initial stage, indicating the improved humification. Once the inoculation with Aspergillus niger was 3%, the seed germination index and the total phosphorus content increased by 2.38%, and 22.3%, respectively, whereas, the degradation rates of cellulose and hemicellulose were 1.36 and 1.42 times higher than those of the control treatment, indicating more conducive to compost maturity. The EEM-FRI demonstrated that a high maturity of compost was achieved with the inoculation of Aspergillus niger, indicating the high degradation of organic matter, and the formation of humus. A correlation analysis also showed that there was a significant correlation between the total phosphorus content and cellulose, humic acid, and fulvic acid after adding Aspergillus niger. Consequently, the high compost maturity and cellulose degradation can be achieved to enhance the quality and nutrients of the products. The cow manure compost with 2%-3% Aspergillus niger can also be inoculated to efficiently promote the resource utilization of cow manure in cattle farms. [ABSTRACT FROM AUTHOR]

Reverse Osmosis (RO) is one of the most advanced and effective membrane separation treatments in desalination. Forward Osmosis (FO) is also one type of membrane separation that can spontaneously draw the water from the RO concentrated water. However, the regeneration of draw solution requires much energy in the FO system. A Fertilizer-Drawn Forward Osmosis (FDFO) process is thus selected to reduce the energy consumption for the draw solution, where the fertilizer solution was used as the draw solution. The RO concentrated water is continuously concentrated, while the fertilizer draw solution is continuously diluted in the process of FDFO. The diluted fertilizer draw solution can widely be expected for the agricultural irrigation without regeneration. In this study, the influence factors of the forward water and reverse salt flux in the FO process were determined under the different type, concentration, and temperature of draw solution, as well as the concentration of feed solution. KCl, KNO3, NaNO3, NH4HCO3, (NH4)2SO4, and NH4Cl were selected as the draw solutions for the single factor comparison tests of FDFO. The results show that the forward water fluxes and reverse salt fluxes differed greatly with different kinds of draw solutions. The forward water fluxes of draw solutions were ranked in the order of KCl > NH4Cl > NaNO3 > NH4HCO3 > (NH4) 2SO4 > KNO3. The reverse salt flux was NaNO3 > NH4HCO3 > KNO3 > KCl > NH4Cl > (NH4)2SO4. The forward water flux of KCl and NH4Cl was the largest, while the reverse salt flux was smaller. Therefore, KCl and NH4Cl were more suitable for a single fertilizer draw solution. A FO test was carried out under the different concentration and temperature of KCl draw solution. The results showed that the forward water flux of KCl draw solution at 2 mol/L was 3.56 times than that of 0.5 mol/L, and the forward water flux of KCl draw solution at 55℃ was about twice than that of 25℃. Therefore, the forward water flux increased significantly, with the increase of the concentration and temperature of draw solution. However, there was no increase in the forward water flux and the reverse salt flux, when the concentration of draw solution increased exponentially. Additionally, the increased multiple of forward water and reverse salt flux was less than the draw solution concentration. Another FO test was also carried out under the various concentration and temperature of NaNO3 draw solution. The results showed that the reverse salt flux increased by 2.94 times, when the concentration of NaNO3 draw solution increased from 0.5 to 2 mol/L, while, the reverse salt flux increased by 1.64 times, when the temperature of NaNO3 draw solution increased from 25 to 55℃. Therefore, the reverse salt flux increased, with the increase of the concentration and temperature of draw solution. Furthermore, the temperature increased exponentially, so did the forward water flux. Since the RO concentrated and deionized water were selected as the feed solution in the FO experiment, it was found that the higher concentration of feed solution, but the smaller forward water flux. [ABSTRACT FROM AUTHOR]

Excessive accumulation of trace elements in the protected cultivation soil has become an important factor for the degradation of soil quality. In particular, both copper (Cu) and zinc (Zn) are micronutrient elements required for plant growth and heavy metal in the soil environment. It is highly demanding to consider the Cu, Zn cumulative risks. Therefore, this study aims to investigate the accumulation characteristics and risk prediction of Cu, Zn content in the protected cultivation soil. A total of 131 soil samples were also collected using 5-point sampling in the typical regions of 16 cities in 7 provinces and 1 autonomous region (including Liaoning, Hebei, Shandong, Henan, Shaanxi,, Jiangsu, Yunnan, and Ningxia) in China. The cumulative status and risk characteristics of Cu and Zn were systematically analyzed using the total and available content of the soil. The relationship between the accumulation of available Cu, Zn, and the planting years was fitted to predict the risk of Cu and Zn accumulation exceeding the limit value. The results showed that: 1) The total Cu and Zn exhibited an accumulative characteristic in the protected cultivation soil, except that Cu presented a slight decrease in Jiangsu. The effective state content of Cu and Zn (except that Zn at a relatively rich level both in Shaanxi and Jiangsu) reached an extremely rich level, where there was no state below the critical value. Noted that the soil background values in each province were compared with the abundance and deficiency indexes of soil available trace elements in the agricultural system. 2) The total amount of Cu and Zn in the soil exceeded the standard by 16.03% and 4.58%, respectively, compared with the screening value of farmland soil. The average exceeding limit rate reached 16.92%, while Liaoning, Henan and Yunnan were observed the most serious up to 33.33%, 62.50%, and 32.00%, respectively, compared with the risk limits of soil available Cu and Zn. 3) The risk assessment showed that the overall performance of protected cultivation soil was safe using the effective state. The samples from Liaoning, Henan, and Yunnan reached the level of lightly, lightly pollution, and warning value level, respectively. The cumulative risks of elemental Cu were more serious than Zn element. 4) There was a significant positive correlation between the accumulations of soil available Cu and Zn with the corresponding planting years (P<0.05). The continuous replanting for 6.7, 20.5, and 19.3 years led to the accumulation of available Cu in soils with acidic, neutral, and alkaline limit values of characteristics reach risk, respectively, under the current protected cultivated conditions. At the same time, the continuous replanting for 32.5, 67.9, 91.9 years led to the accumulation of available Zn in the soils with acidic, neutral, and alkaline limit values of characteristic reach risk. The bioavailable state of trace element was used to evaluate the exceeding limit rate of Cu and Zn, while the cumulative risk in the protected cultivated soil, in order to achieve the safe utilization via transforming the excess bioavailable to low state, (such as residue, oxidizable, and reducible state). Therefore, there was a high risk in the accumulations of Cu and Zn in the protected cultivated soil in the practice, where the trends were ever increasing year by year. Consequently, it is necessary to take reasonable and safe measures (including restoration technology and selection of agricultural materials), further to ensure the healthy and sustainable development of protected cultivated agriculture. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Heavy metal contamination of agricultural soil has posed risks and potential dangers to human and livestock, due mainly to most heavy metals are toxic in nature that can cause serious health illness, even at very low concentration. Excessive heavy metals, such as lead, enter the ecological system from the agricultural runoff and industrial discharges to agricultural products of food chain. Since both high geological background and mining activities simultaneously determine the agricultural soils in eastern Yunnan, the lead pollution in agricultural soil has drawn much widespread attention recently. In this study, a simultaneous sampling and analysis test was performed on agricultural soils and products in 6 cities (prefectures) in eastern Yunnan, China, aiming to characterize the lead accumulation in agricultural land. A health risk assessment model was used to evaluate the health risks that caused by lead in the agricultural soils in eastern Yunnan to residents. A species-sensitive distribution model (Log-logistic) was used to construct the lead sensitivity distribution frequency curve (SSD) of different crop varieties, and to reverse benchmark values of soil lead safety, according to the protection of 95% and 5% of crop categories. The result showed that: 1) The average content of lead in agricultural soils from various cities (prefectures) in eastern Yunnan was from more to less in the order of Honghe Prefecture, Qujing city, Zhaotong city, Wenshan prefecture, Yuxi city,Kunming city. The average lead content of Zhaotong city, Qujing city, Wenshan prefecture, and Honghe prefecture exceeded the screening value of lead pollution risk released by National Standards of China. 2) The total point exceeding rate of agricultural products in the 6 cities (prefectures) of eastern Yunnan was 11.9%, where the various types of crops showed the different ability of absorbing and enriching lead. Specifically, peas and peanuts from beans had higher lead accumulation capacity, followed by lettuce from rhizome, rape from leafy vegetables, and wheat from cereals. 3) The health risk assessment showed that there was no significant non-carcinogenic risk and carcinogenic risk to the residents. The non-carcinogenic risk of lead to children was higher than that of adults in various regions of eastern Yunnan, where the non-carcinogenic health risk index (NHI) of various exposure routes was ranked from much to less in the order of hand-oral intake, skin exposure, breathing inhalation. (4) In the species sensitivity distribution model (Log-logistic), the benchmark values of soil lead health risk were inversely deduced for agricultural products in eastern Yunnan. When rhizomes, nightshades, planting beans, cereals crops were planted, the critical value of Pb were13.0, 19.7, 35.1, 11.3, 18.1 mg/kg, respectively; and the alarm value of Pb were 269.5, 481.3, 500.7, 367.5, 560.3 mg/kg, respectively. It can provide scientific basis for establishing more accurate local standard and realizing the safe utilization of lead-contaminated soil in agricultural soil in eastern Yunnan and similar regions. [ABSTRACT FROM AUTHOR]

Fluvo-aquic soil is a typical cultivated soil with the widely distribution and high intensity of fertilization in China. However, the accumulation and loss of phosphorus in fluvo-aquic soil cannot be ignored as the ecological changes. In this study, the typical fluvo-aquic soils were collected as the test soils with different phosphorus levels (high, medium, and low) in Henan province, China, in order to explore the characteristics of phosphorus loss from fluvo-aquic soil induced by surface runoff and leaching. Simulation experiments of an artificial rainfall and a soil column were conducted to measure the content of Olsen-P and soluble active phosphorus (CaCl2-P) in soils, and the concentrations of different forms of phosphorus in runoff or leaching. In a split-line model, the relationship between soil Olsen-P content and Total Phosphorus (TP) in solution was used to evaluate P risk from black soil in surface runoff and leaching. The results showed that: 1) The contents of Olsen-P and CaCl2-P in fluvo-aquic soil profiles were in the order of high, medium and low phosphorus level, whereas, the soil phosphorus sorption index value were in the order of low, medium and high phosphorus level. In the profile distribution of phosphorus, the content of Olsen-P and CaCl2-P in fluvo-aquic soil with low and medium phosphorus level decreased with increasing soil profile, while the content of Olsen-P and CaCl2-P in fluvo-aquic soil with high phosphorus level was the highest in the 20-40 cm soil layer. 2) The concentration and losses of TP, Total Dissolved Phosphorus (TDP) and particulate phosphorus (PP) in the runoff from fluvo-aquic soils with different phosphorus levels were in the order of high > medium > low phosphorus level, and the PP dominated in fluvo-aquic soil runoff. 3) The concentration and loss of various forms of phosphorus in the leachate of low- and medium-phosphorus level from fluvo-aquic soil decreased with the increasing soil depth. However, in the leachate of high phosphorus level, the concentration and loss of phosphorus in the 20-40 cm soil profile were significantly higher than those of in other soil profiles, where the phosphorus concentration in the whole profile increased first and then decreased with the increasing soil profile, whereas, the profile of high phosphorus level presented the distribution pattern that upper and lower was low, and middle was high. The leaching loss of fluvo-aquic soil was dominated by TDP. The high- and low-phosphorus fluvo-aquic soil was dominated by Dissolved Organic Phosphorus (DOP), while the medium-phosphorus fluvo-aquic soil was dominated by Molybdate Reactive Phosphorus (MRP). 4) The relationship between CaCl2-P and Olsen-P were characterized using split-line models, identifying the thresholds at 24.65 Olsen-P mg/kg for the fluvo-aquic soil. It was also pointed out that the TP concentration in runoff and leachate was positively correlated with the CaCl2-P content in soil, and that CaCl2-P can be used to predict the phosphorus concentration of water discharged from soil. The outcomes derived from these experimental conditions regarding the determination of P loss in runoff by the artificially simulated rainfall experiment. The P loss in leaching by the soil column method and P environmental thresholds also need further verification in the field. This finding can help to assess phosphorus loss from fluvo-aquic soil under different phosphorus levels, and further to provide a scientific basis for water environment protection and soil phosphorus management in fluvo-aquic soil areas. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to solve the problems of zero discharge of reverse osmosis (RO) brine, the coupling matching of solar collector and membrane distillation, the cooling water reduction and phase change heat recovery in the steam condensation process of membrane distillation system, the RO brine desalination system by solar vacuum membrane distillation in cold area was designed and verified in the test. The system consists of RO concentrated tank, membrane distillation module, solar collector, condensing unit, circulation pump, vacuum pump, fresh water tank, and so on. The condensing devices are self-made stainless steel heat exchange coil placed in the RO freshwater pool and geothermal coil placed in the underground of the greenhouse. The components of the system are designed in detail, and the self-made condensing device is the focus in the design. The system is placed in a greenhouse in Xinrong Village, Helan County, Yinchuan City, Ningxia. The front end of the system is an RO system for greenhouse irrigation. Since RO concentrated water cannot be discharged, it is further diluted by vacuum membrane distillation. In order to reduce energy consumption, the RO concentrated water treated by membrane distillation is heated by a solar collector. The fresh water vapor produced by membrane distillation is cooled by the stainless steel heat exchange coil in the RO fresh water tank and the greenhouse geothermal coil, which solves the problem of cooling water reduction in the steam condensation process of the membrane distillation system, and realizes phase change heat recovery and heats the greenhouse. Through measuring the relevant parameters of each component of the system, the solar collector effect, the RO brine desalination effect of the vacuum membrane distillation, the condensation effect of the condensing device and the heating effect of the greenhouse crop were tested and analyzed. The tests show that under the test conditions, the selected collector area can basically meet the heat requirement of membrane distillation for the whole year, the length of the stainless steel heat-dissipating coil designed in the greenhouse fresh-water tank can meet the steam condensation requirement, and the geothermal coils laid in 30-40 cm depth below the surface can meet condensation requirements and greenhouse heating requirements. The amount of freshwater produced by membrane distillation increases with the increase of the inlet temperature of the RO brine on feeding side and the vacuum pressure on the permeate side. When the inlet temperature of the RO brine on feeding side is 80 °C and the vacuum pressure of permeate side is -0.080 MPa, the water production is 37.62 L/h. When the operating time of the vacuum membrane distillation system reaches 240 h, the membrane fouling increases and the water production decreases. When the hollow fiber membrane is cleaned, the water production after washing is increased by nearly 1.5 times compared with that before washing. It has been verified by experiments that the RO concentrated water desalination system by solar vacuum membrane distillation in cold area can basically meet the requirements for use. This study has important significance for reducing the energy consumption of membrane distillation system, realizing the zero discharge of RO brine, and reducing the concentration of brine in the environment. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)