Disintegration Dynamics Of Different Green Manures And Their Effects On Soil Nutrients

The paddy fields in the south of China have a wide area,and the continuous cropping situation is widespread and excessive use of chemical fertilizers leads to a decline in soil fertility,which affects the effective use of land resources and is not conducive to the sustainable development of agriculture.Green manure stalk returning can exert its superior fertility effect and ecological protection function,and alleviate the contradiction problems in soil cultivation in the south.In this study,a net bag method was used to simulate the return of green manure,and combined with indoor laboratory analysis methods,the speed of decomposition of different green manures in southern paddy fields and the release characteristics of carbon,nitrogen,phosphorus,and potassium were studied.The impact of soil fertility,so as to select a green manure return program suitable for the development of southern paddy fields.The main findings are as follows:(1)Decomposition characteristics and nutrient release of green manure in southern paddy fieldsNylon mesh bag method was used to study the arrowhead peas,alfalfa,Euonymus,Ziyunying,ryegrass 1:3 arrowhead peas,ryegrass 1:1 arrowhead peas,ryegrass 3:1 arrowhead peas in southern water Tanaka's decomposition and nutrient decomposition dynamics.The results showed that:(1)The change curve of dry matter residue and dry matter residue ratio after the overturning of green manure was basically consistent,and the relationship between nutrient release rate and overturning time could be fitted by logarithmic equation.0-12 d,the rapid decomposition of fresh green manure.12-50 d,which is the mid-speed decomposition period of fresh green manure,and 50 d later,it is the slow decomposition phase of green manure,in which the decomposition rate of green manure with higher moisture content is higher than that of green manure with lower moisture content.(2)The cumulative release rates of carbon,nitrogen,phosphorus,and potassium were 58.14%-63.02%,74.61%-88.29%,68.01%-78.48%,and 72.56%-81.94%,respectively.The cumulative release rate of nitrogen was the highest.,(3)The green manure released the most nitrogen within 70 d after being buried.(4)The distribution rate of carbon,nitrogen,phosphorus,and potassium in the arrowhead peas and ryegrass 3:1 peas treated within 70 d after rolling was lower than other green manure treatments.(2)Effect of green manure on fertility of paddy field in South ChinaThe main results of the experiment were as follows:(1)Green manure returned to field for 70 d,all could increase soil organic matter,active organic carbon,total N,P,K,alkali-hydrolyzed nitrogen,available phosphorus,and available potassium,and there was no significant difference between different green manure treatments.(2)After the manure was overturned for 50 d,the content of soil organic matter had a greater impact,and the impact of the first 50 d was smaller.At the end of the experiment,it was best to increase 11.73% with arrowhead pea treatment.(3)During the first 50 d after returning green manure,the soil active organic carbon content showed an upward trend,decreased after 50 d,returned to the field for 70 d,and the best treatment was to increase the rye grass 1:1 arrowhead peas by 44.93%,and the green manure was returned to the field.The effect is better than that of green manure alone.(4)After the manure was overturned for 50 d,the total N,P,K,available potassium,available phosphorus,and alkali-hydrolyzable nitrogen content had a great influence on the soil,with minimal impact on the first 50 d.(5)At the end of the experiment,the contents of total N,K,available phosphorus,and available potassium in the soil treated with V.vulgaris were the highest and increased by 5.36%,1.62%,11.94%,and 28.88%,respectively;9.61%;Alkali-nitrogen content increased the most is the treatment of alfalfa,an increase of 5.74%.