Effects Of Chinese Milk Vetch,Rice Straw And Their Combined Application On Soil Nitrogen Transformation

Both green manure Chines milk vetch and rice straw are high-quality bio-derived organic fertilizers and straw returning and winter green manure are also important fertilization techniques in southern China.Due to the limitation of carbon and nitrogen composition,green manure or straw returning to the field has certain limitations.The combination of the two can help to achieve complementary advantages,improve soil quality,protect the ecological environment,and promote green agricultural production.The effect of combined action with rice straw on soil nitrogen transformation and its mechanism are still unclear.In this study,the soil-cultured simulation experiment was used to explore the mechanism of the combination of Chinese milk vetch and rice straw in improving soil fertility,soil nitrogen capacity and soil nitrogen availability from the perspective of soil nitrogen supply and transformation.The main results are as follows:1.In the constant addition test,the combination of Chinese milk vetch and rice straw showed a significant increase in soil nitrogen activity,and the soil mineralized nitrogen content increased by 583.88 mg/kg compared with CK in the most intense culture.DON significantly increased the concentration of 53.16 mg/kg,and gradually produced positive interaction effects with the culture;at the same time,it effectively increased the content of soil organic nitrogen at the end of the culture,that is,the compounding>Chinese milk vetch single application>straw single application>CK,in which the application of CK acid ammonium release was the most significant increase of70.59%,acid hydrolysis total nitrogen increased by 27.09%,acid hydrolysis of amino acid nitrogen increased by 56.51%.On the other hand,the effect of Chinese milk vetch alone on inhibiting N₂O emission was more obvious in the early 8-12 days of culture.The single application of straw was more obvious in the late stage of cultivation,and the compound treatment showed good inhibition effect in most of the culture.However,the effect of the whole process of straw treatment was the most significant,which was44.86%lower than which of CK.2.Increasing the amount of added materials,it was found that the high-level green manure treatment at the initial stage of culture showed a significant nitrogen increase trend,which was 25.77%higher than that of CK.At this time,the high-strength straw treatment increased by only 5.46%.A slight downward trend.NH₄⁺-N in the whole process of soil culture showed high-yield green manure application>high-allocation application>high-volume straw application>CK;while NO₃^--N showed the best combination,the two treatments were similar,and when cultured for 20 days The most significant;for the acid-soluble organic nitrogen component,the highest content of acid hydrolysis in the high-concentration treatment at the end of the culture was the highest,which was 44.51%higher than that of CK.The other components also showed a certain increase,while the high-yield green fertilizer alone treatment Significantly increased the acid hydrolysis of ammonia nitrogen and amino acid nitrogen,but significantly reduced the amino sugar nitrogen;the high amount of straw single treatment of each nitrogen component increased relatively small.The dynamic change of N₂O release showed that the high amount of green manure was the highest in the early stage of cultivation,and the high amount of straw in the middle stage of cultivation was the first,while the release amount was high in the middle and late stage of cultivation.During the whole cultivation period,high amount of green manure and its The total cumulative increase of N₂O was similar to that of straw treatment,which was significantly higher than that of single straw application.There was no significant interaction between the two.3.Urea combined with organic materials can be found that the degree of decomposition and rate of organic materials is greatly improved due to the addition of urea.Among them,urea and green manure have the best performance,which significantly increases soil mineralized nitrogen,DON and total acid nitrogen content..The content of DON and mineralized nitrogen in the treatment of different organic materials with urea was higher in the early stage of culture,then decreased and stabilized,and the urea and green manure application>urea and two materials combined with urea straw application.During the whole culture period,the total N₂O emissions showed a single application of straw and its application with green manure was significantly higher.There was no significant difference between green manure and urea application and urea application.On the other hand,at the end of the culture,the total nitrogen content of soil acidification in the soil treated with organic materials increased compared with CK,while the urea treatment alone showed a slight decrease.In summary,the combination of Chinese milk vetch and straw can effectively adjust the added material C/N,increase soil microbial activity and soil nitrogen conversion efficiency,also effectively increase soil active nitrogen and reduce greenhouse gas N₂O emissions.Single application of rice straw increased the degree of nitrogen release,and decreased the identification compared with single application of green manure,reduced N₂O emissions,and the soil continued to maintain a high supply of inorganic nitrogen.On the other hand,the combination of urea and green manure showed high-efficiency activation of soil nitrogen,which not only improved the single application of urea at the end of the culture,but also reduced the N₂O increase caused by the combination of the three.Discharge defects,but also stimulate the more complete activation of organic materials and release nitrogen into the soil,become available nitrogen and then absorbed by plants.