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Aluminum toxicity in acidic soil has become one of the main factors limiting crop growth and yield. Rapeseed is an important oil crop in China, which is mainly planted in the provinces and regions of the Yangtze River Basin where soil acidification is more serious. Rapeseed is one of the crops sensitive to aluminum toxicity, but the mechanisms of aluminum tolerance are still poorly understood. This paper reviewed the production of aluminum toxicity, the effect of aluminum toxicity on crop growth, the mechanism of crop aluminum tolerance, and the research progress on aluminum tolerance of rapeseed, and provide reference for the cultivation of new varieties of aluminum tolerant and high yielding rapeseed. [ABSTRACT FROM AUTHOR]

To explore the differences and change rules of soil nutrients and enzyme activities in Larix gmelinii forest in the cold temperate zone, so as to provide scientific basis and data basis for in-depth understanding of forest ecosystem functions and future development trends in the cold temperate forest ecotone in China. In this paper, four different types of larch forest (Betula platyphylla -Larix gmelinii, Rhododendron dauricum-Larix gmelinii, Larix gmelinii, and Larix gmelinii plantation) in Heilongjiang Zhongyangzhan Black-Billed Capercaillie Nature Reserve were selected as the research objects. Sampling was carried out by season, and the soil. chemical properties and enzyme activities ( catalase, acid phosphatase, urease, sucrase and cellulase) were determined in different seasons, and the dynamic changes with seasons were also explored. Results showed that: (1) Soil chemical properties and enzyme activities were significantly different in different forest types and seasons, and the changing trends were also different to some extent. (2)Soil acid phosphatase was significantly affected by the contents of soil total P, total N and available K. Soil catalase was significantly positively correlated with the contents of total N, available N, available K and available P. Soil sucrase was mainly affected by the contents of available P and available N. Soil urease and cellulase were most affected by soil organic carbon content. (3)The principal component analysis showed that there were significant differences in soil enzyme activities and soil chemical properties among the four forest types, and first principal component 1 could explain more than 50% of the variance variables. The soil chemical properties and enzyme activities in different Larix gmelinii were significantly different with the seasons, which were related to the accumulation of litter and the difference of vegetation types. Soil enzyme activities were correlated with soil chemical properties to varying degrees. [ABSTRACT FROM AUTHOR]

[Objectives] This paper was aimed to study the remediation effects of phosphate-solubilizing fungi and bone char in different soils. [Methods] Three different types of lead-contaminated soils (neutral yellow brown soil, alkaline sand soil and acidic red soil)were mixed with the bone char sintered at different temperatures. We measured the contents of phosphorus and lead, and the remediation differences of different soils. The Pb bioavailability of lead-contaminated soil was then determined by planting non-heading Chinese cabbage. The application potential of compound remediation materials was confirmed by adding compound remediation agents to the soil with the best remediation effect. [Results] The bone char had the best effect of promoting the release of phosphorus in yellow brown soil, and the available phosphorus content was 64 times higher than that of the control, showing a high potential of lead remediation. The pH of yellow brown soil was neutral, and the available P in the soil would not be fixed by Ca, Fe, Al, etc., thus increasing the probability of its reaction with Pb. When bone char was solely used, the material treated at 200-300 ℃ had qualified remediation effect. We planted non-heading Chinese cabbage to verify the bioavailability of lead in yellow brown soil after bone char application. It was observed that addition of a certain proportion of bone char to yellow brown soil (the initial mass ratio of bone char to lead was over 0.5:1) could not only increase the absorption of phosphorus by 2.0 to 3.5 times, but also reduce the absorption of lead by non-heading Chinese cabbage(content of lead in pakchoi leaves was reduced by 70% to 80% compared with blank treatment). A composite of bone char and Aspergillus niger was further applied to yellow brown soil, and the effective lead was reduced to 14.36 mg·kg-1. In particular, the growth of the A. niger proved the remediation potential of the composite. [Conclusions] The composite of bone char and A. niger was suitable for lead remediation in neutral soils, and the suitable heating temperature for preparing bone char was 200-300 ℃. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to explore the effects of manganese stress on acid soil nitrogen conversion, enzyme activity and sugarcane nitrogen absorption and utilization, and provide a reference for the rational fertilization of sugarcane on acid soil. [Method JSimula- ted acidic soil manganese stress cultivation experiment in the indoor, and the sugarcane pot experiment in the glasshouse were carried out, and the difference of soil nitrogen component content, pH and soil enzyme activity under manganese stress and its relationship with sugarcane nitrogen absorption and accumulation relationship were measyured and analyed. [Result] Manganese stress significantly increased soil ammonium nitrogen content and net ammonification rate(P < 0. 05,the same as below), significantly reduced soil nitrate nitrogen content and net nitrification rate, and significantly increased soil net mineralization rate. At the same time, manganese stress significantly reduced soil urease activity and significantly increased soil invertase activity, but had no significant effect on soil protease activity (P >0. 05). The results of correlation analysis showed that soil urease activity was significantly and extremely (P < 0. 01, the same as below) positively correlated with soil ammonium nitrogen content and pH, soil protease activity was significantly positively correlated with soil ammonium nitrogen content, and extremely and significantly negatively correlated with soil nitrate nitrogen content and net nitrification rate respectively. Under manganese stress, sugarcane plant height, biomass, plant nitrogen accumulation and nitrogen absorption efficiency were significantly reduced. [Conclusion] Manganese stress can inhibit the nitrification of acid soils, reduce the conversion of ammonium nitrogen to nitrate nitrogen, and at the same time reduce the activity of soil urease and increase the activity of soil invertase, thereby reducing the available nitrogen content of sugar- cane in acid soil, reducing the absorption and utilization of nitrogen by sugarcane. [ABSTRACT FROM AUTHOR]

[Objective] The aim of this paper is to explore the relationship between the main chemical components of flue-cured tobacco and soil chemical properties. [Method] All of 235 tobacco leaf samples and soil samples were collected from typical aromatic tobacco growing areas in Yunnan province. The main soil factors affecting the chemical quality of Yunnan fragrant tobacco leaves were studied by correlation analysis, stepwise regression analysis and principal component analysis. [Result] The contents of total sugar and reducing sugar in Yunnan tobacco were 30.87% and 27.21, respectively ;the contents of total nitrogen, nicotine and potassium were in the appropriate range, which were 1.91, 2.63% and 1.91% respectively ;The results showed that the pH value of the main tobacco planting soils in Yunnan was moderate, with an average of 6.3. The contents of total nitrogen, total phosphorus, available molybdenum and available sulfur were in the rich level. The contents of total potassium and humic acid were on the low level. The contents of organic matter, fulvic acid, available boron, water-soluble chloride ion, salt content and CEC (total amount of cation exchange) were in the middle level. The contents of total sugar, reducing sugar, starch and potassium in tobacco leaves were significantly positive correlation with total potassium in soil. Two sugar difference and sugar alkali ratio were significantly positive correlation with soil available molybdenum content. Two sugar difference was significantly positive correlation with soil humic acid content, and was significantly negative correlation with soil chloride ion content. [Conclusion] The contents of total potassium, available molybdenum, humic acid and water-soluble chloride ion in tobacco growing soil of Yunnan tobacco growing areas are the most important indicators affecting the chemical quality of tobacco leaves in Yunnan. [ABSTRACT FROM AUTHOR]

[Objective ] The objective of the paper is to provide the scientific basis for reducing chemical fertilizer and improving efficiency for vegetable in acidic yellow soil area of Guizhou. [ Method] The effects of combined application of biochar and yellow phosphorus slag on yield and nutrient uptake and utilization of Chinese cabbage cultivated in acidic yellow soil are studied by a pot experiment in green house. [ Result] The yield of Chinese cabbage under different treatments of biochar and yellow phosphorus slag combination is increased by 37.22 % - 82.07% compared with that of non-fertilization treatment, and the yield of Chinese cabbage applied with chemical fertilizer + 70 glpot biochar + 11.7 glpot yellow phosphorus slag is the highest ( 553. 5 g/ pot) . The nitrogen, phosphorus and potassium content in Chinese cabbage under different treatments of biochar and yellow phosphorus slag combination is increased by 39.9% - 57.9%, 1.31% - 35.22% and 1.99 % -39.09% respectively compared with that of non-fertilization treatment. The nitrogen, phosphorus and potassium uptake of Chinese cabbage under different treatments of biochar and yellow phosphorus slag combination is increased by 107.8% - 188.9%, 65.89% - 128.82% and 61.73 % - 122.97% separately. Except there is no obvious difference in phosphorus uptake of Chinese cabbage applied chemical fertilizer + 18.0 glpot yellow phosphorus slag and non-fertilization treatment, the nitrogen, phosphorus and potassium uptake of Chinese cabbage under other treatments of biochar and yellow phosphorus slag combination is higher than that of nonfertilization treatment significantly. Among various fertilization treatment, chemical + 70 glpot biochar + 11.7 g/pot yellow phosphorus slag has the highest nitrogen and phosphorus utilization efficiency, respectively 59. 01 % and 8. 83 %, while chemical fertilizer+ 100 glpot biochar + 9.00 glpot yellow phosphorus slag has the highest potassium utilization efficiency, which is 92. 10 % . [Conclusion ] Rationally combined application of biochar and yellow phosphorus slag can improve yield, nutrient uptake and utilization of Chinese cabbage, and low amount of biochar combined with high amount of yellow phosphorus slag has the best effect. [ABSTRACT FROM AUTHOR]

Northern China is the main intensive agricultural area for winter wheat-summer maize production in China. In the past 30 years, chemical nitrogen (N) fertilizer was the main source of N input in the farmland ecosystem and plays a key role in crop production and soil quality. Due to the excessive application of chemical N fertilizer and frequent irrigation, fertilizer N usage efficiency was low and was also lost into the environment and this caused many negative environmental pollutions. Among the fates of fertilizer N applied, ammonia volatilization was an important gaseous N loss, and it was one of the main sources of atmospheric ammonia and significantly contributed to the formation of atmospheric pollutant PM2.5. Besides, compared with the acid soil in southern China, the proportion of ammonia volatilization from calcareous soil after N fertilization in northern China was higher. In the past, although many experimental studies have been carried out on ammonia volatilization in northern China Plain, few have systematically investigated the relationship between ammonia volatilization and fertilizer N used, and the efficacies of different ammonia collection methods, i.e., sponge absorption method and vacuum suction method. In this study, the works of literature on ammonia volatilization during the winter wheat season in northern China published from 1980 to 2018 were collected and the methods of regression analysis and T-test were adopted. Among the 31 papers collected in this study, 17 adopted the sponge absorption method and 14 adopted the vacuum suction method to measure the ammonia volatilized after N fertilization during the winter wheat season. The results showed that under farmer’s conventional N fertilization level, the cumulative total ammonia and net ammonia volatilization was exponentially (y=2.64e0.006 6x)and power-functionally(y=0.004 8x1.358 9) correlated with the fertilized N rate, respectively. Correspondingly, the average proportion of net ammonia volatilization to total chemical N applied was (6.27±0.98)%. Under the same N rate at the basal and topdressing stages, the corresponding ammonia volatilization was 58.7% and 41.3% of the total ammonia volatilization in the whole wheat season, indicating the higher contribution of N volatilization at the basal stage, and the importance of mitigation the ammonia volatilization for winter wheat season. At the fertilization rate of 180 kg/hm² during the winter wheat season, the ammonia volatilization determined by the vacuum suction method and the sponge absorption method was similar. At the fertilization rate of <180 kg/hm², the ammonia volatilization determined by the sponge absorption method was 0-5% higher than that of the vacuum suction method and at 180-400 kg/hm², the vacuum suction method was 0-6.9% higher than that of the sponge absorption method, although the statistic differences between these two methods were not significant. This study also found the priming effect of the ammonia volatilization due to chemical N fertilization was 21.8%±3.57%; the net ammonia volatilization determined without considering of priming effect was significantly higher than that determined with considering of priming effect. The mitigation of ammonia volatilization in the winter wheat season should focus on optimizing the N fertilization rate, mainly at the basal fertilization stage, and combined with other farming measures such as drip irrigation and soil mulching). During the field study of ammonia volatilization caused by chemical N fertilization, the priming effect and the overestimate of ammonia volatilization should not be neglected. Differences of NH3 volatilization via the sponge absorption method and the vacuum suction method should also be taken into consideration. [ABSTRACT FROM AUTHOR]

To evaluate reasonably the effect of reclaimed water irrigation salt in the soil environment, varying salinity in the effluent of salty solution leaching subtropical soil and the effect on soil chemical properties were analyzed. In this paper, five subtropical soils: clay fluvo aquic soil, sandy fluvo aquic soil, red soil, purple soil and paddy soil were selected as the research object. Use the constant head infiltration method to observe the differences in electrical conductivity (EC) and pH of effluent after leaching of soils with different concentrations of sodium salt solution (EC of solutions was 1.96, 4.77, 9.08, 17.25 and 25.06 dS/m, respectively). The results showed that the high concentration salt solution had weaker penetrating ability in red soil, purple soil and clay fluvo aquic soil with higher clay content than paddy soil and sandy fluvo aquic soil with low clay content. The same treatment achieved the same degree of penetration, and acidic soil (red soil, purple soil, paddy soil) can withstand more low quality water. In addition, the migration rate of salinity in the soil was mainly determined by the physicochemical properties of the soil. Soil clay content and exchangeable aluminum content significantly slowed the migration of salinity in the soil, while the soil silt content, EC, pH value and exchangeable calcium and magnesium content promoted the migration of salt in the soil. Salt can easily flow out through alkaline soil (clay fluvo aquic soil and sandy fluvo aquic soil). The maximum change rate of relative EC from the alkaline soil effluent was 36% higher than that of the acidic soil. The concentration of inflow salt had an obvious influence on the relative EC change rate and the penetration process of the red soil effluents, and it mainly affected the relative EC change rate for the purple soil, the clay fluvo aquic soil and the sandy fluvo aquic soil, which mainly affected the lag degree of the penetration process for paddy soil. The Boltzmann fitting showed the infiltration water salt concentration and soil physical and chemical properties had a significant impact on the model parameters (P<0.05). Moreover, the degree of soil chemical properties affected by the salt concentration in the infiltration solution was not only related to its own chemical properties, but also had a very significant relationship with the content of powder particles and clay in the soil texture (P<0.01). The concentration of salt solution had no significant (P > 0.05) effect on the pH value of alkaline soil, and had a greater effect on the pH value of acidic soil. The pH of the effluent decreased by 1.6-2.6 units, of which red soil had the greatest change in pH value, followed by purple soil. The influence of infiltration solution with EC higher than 4.77 dS/m on the stable pH value of soil effluent did not increase substantially. Therefore, when irrigating with low quality water, the salt concentration in the water should be sufficiently limited according to the physicochemical properties of the soil. The research results can serve as reference for reclaimed water irrigation and calculation of water and salt transport in subtropical regions. [ABSTRACT FROM AUTHOR]

[Objective] In this paper, the problem of acidifying soil in Baoshan tobacco-growing area was studied.[Method] Six kinds of soil conditioner were selected as soil remediation measures to study the effects of different soil conditioner on the chemical properties of acid soil and the quality and yield of flue-cured tobacco.[Result] In addition to calcium magnesium phosphate fertilizer, the other soil conditioners could improve the soil pH, of which lime was the best, however, application lime was alone, it was easy to produce calcium magnesium potassium antagonism, and soil fertility declined.Potassium fertilizer and new pattern potassium fertilizer could increase the content of soil a-vailable K, slow K and tobacco potassium to achieve increased potassium content and improve quality.The contents of available potassium and slowly available K in the 0 - 15 cm soil mineral potassium (hydrothermal) with 62.13 %, 33.97 % were significantly higher than those iii lime treatment, and mineral potash (calcination) with 82.59 %, 24.01 % were significantly higher than those in lime treatment.Soil conditioner mainly affected the chemical composition of tobacco leaves and the smoking quality of the middle and upper leaves.The content of alkali-hydrolysable N in soil and the yield of flue-cured tobacco under the new-type potassium organic fertilizer treatment were higher than that of CK 13.04 %, 316.85 kg/hm2, respectively.The effects of two kinds of soil amendment on the chemical composition of tobacco leaf and the smoking quality of tobacco leaf were the best with the new type potassium bio-organic fertilizer and mineral potassium fertilizer (hydrothermal method).[Conclusion] The effects of soil pH, nutrient and the quality, yield of flue-cured tobacco by mineral potassium fertilizer (hydrothermal method) and new type potassium bio-organic fertilizer were improved. [ABSTRACT FROM AUTHOR]

With the continuous development of industry, environment pollution such as soil acidification and heavy metal pollution of soil becomes increasingly serious, especially in the acidic soil region of southern China. Liming is a traditional and effective method to improve acidic soil. Manual spreading is a kind of traditional method of liming, but it is inefficient and has some side effects like skin damage of workers because of the corrosive property of lime. In order to solve the deficiencies of manual liming and compensate the technology gap of liming machine between domestic and overseas market, we designed a lime spreading machine which was able to be assembled with other agricultural machinery to become combined machine. The development of liming machine has great significance to improve liming efficiency and working conditions. This paper discussed the structure and working principle of the pros spiral lime spreading machine. The machine used the spread roller which was similar to the structure of pros spiral as working parts, used the overlapped waist-shaped hole as the lime spreading outlet, and controlled the waist-shaped hole overlapping area through adjusting assembly to adjust the lime spreading amount. Through experiment we determined the lime outlet size and the lime spreading roller's rotation speed of the lime spreading machine, and experiment results showed that: Firstly, when the lime spreading roller speed was below 125 turn per minute, for the same waist-shaped lime spreading outlet, the lime spreading amount per turn of lime spreading roller could be treated as a constant value, i.e. the spreading amount and lime spread roller's rotation speed were in a linear relationship; Secondly, when the number of lime spreading plate was 40, the hole was waist-shaped hole with the size of 25 mm*10 mm and the rotation speed of the roller was in 120 turn per minute, we got the lime spreading amount of 1 500 kg/h which met the maximum requirements of lime spreading. Considering the linear relationship between the lime spreading amount and the number of lime spreading hole, and the complex conditions after assembled with rotary cultivator, we increased the number of the waist-shaped hole and decreased the rotation speed of lime spreading roller meanwhile kept the lime spreading speed unchanged, and at last determined the lime spreading hole number to be 60 and the roller's rotation speed to be 80 turn per minute as the optimal scheme. We also analyzed the power consumption condition of the lime spreading process and calculated the total power consumption of the working process. Finally, the field test of the lime spreader was carried out, which was conducted in the dry paddy field. Field test results showed that, under the conditions of the lime spreading cultivator at a speed of 5 km per hour, the lime spreading roller at a speed of 80 turn per minute and the overlapping area of the lime spreading hole at maximum size, when the adjusting bar of adjusting mechanism was located in Location XIII, the lime spreading amount reached 1 566.7 kg per hectare. When the adjusting bar of adjusting mechanism were located in Location XII, X and VII, respectively, the lime spreading amounts met the demands of annual lime spreading amount for the first, second and third year, respectively; and when the adjusting bar was at Location II, lime spreading machine almost closed all the lime spreading holes. [ABSTRACT FROM AUTHOR]