Effect Of Different Straw Returning Methods On Soil Properties And Rice Yield

The practice of returning straw to the field is an effective means to ensure soil fertility and maintain and enhance crop productivity in agricultural ecosystems,and it is of great significance for the resource utilization of agricultural waste.However,due to the slow decomposition of straw after returning it to the field,straw returning can cause many problems such as soil-borne diseases.Currently,there are many different methods of straw returning,but the best method is not yet clear.In this experiment,four methods of straw returning were studied,including not returning straw to the field as a control(CK),directly returning straw to the field(F1),returning carbonized straw to the field(F2),returning straw with decomposing agent to the field(F3),returning straw base materialization to the field(F4).Rice pot experiments were conducted to study the effects of different straw returning methods on soil properties and rice yield.The main research results are as follows:(1)Different straw returning methods can effectively increase soil nutrient content.The content of available nitrogen and potassium in the soil in the F3 treatment increased by 17.01%and 24.28% compared to the control,respectively.However,the F1 treatment only increased by 8.7% and 12.57%.The soil organic matter content was highest in the F2 treatment,reaching 15.12 g/kg,which was 8.31% higher than the control,which may be related to the rich carbon properties of biochar.The straw returning method with the addition of decomposing agents has the greatest effect on soil nitrogen,phosphorus,and potassium nutrients,because the agents can accelerate straw decomposition and nutrient release,thereby improving soil nutrient content.(2)Different straw returning methods have different affect to soil mineral nitrogen content,and nitrification potential.Compared with the control,the ammonium nitrogen content in the soil in F4 treatment increased by 147.8%,nitrate nitrogen content in the soil in F3 treatment increased by 68.63%.The nitrification potential of the soil in each straw returning treatment was improved to varying degrees,with the greatest increase in the straw returning treatment with the addition of decomposing agents,which increased by 88.15%compared to the control.The increase of soil mineral nitrogen and nitrification potential is beneficial to accelerate the nitrogen cycle in the soil.(3)Different returning methods have different effects on soil enzyme activities.Compared with the control,the soil urease and cellulase activities increased by 51.02% and61.86% in the F3 treatment.However,the F2 treatment showed minimal changes in the activities of cellulase and sucrase in the soil.The F4 treatment showed the highest activities of nitrate reductase and nitrite reductase in the soil,with increases of 61.57% and 70.42%,respectively.The stronger soil enzyme activity in F3 and F4 treatments indicated faster straw decomposition rate and increased microbial activity in the soil.(4)Different returning methods have varying degrees of impact on microbial quantity and community structure in the soil.Compared with the control,the F3 treatment showed the greatest increase in the quantity of bacteria and fungi in the soil,with increases of 511%and 201%,respectively.The F4 treatment showed the highest increase in the quantity of actinomycetes in the soil,with an increase of 163%.The relative abundance of Proteobacteria in the bacterial community increased by 11.02% in the F4 treatment,while the relative abundance of Zygomycota in the fungal community increased by 4.27% in the F3 treatment.Returning straw combined with microbial agents can significantly improve the quantity of soil microorganisms and the relative abundance of dominant populations,thus enrich the microbial community structure in the soil,and enhance the metabolic activity of microorganism.(5)Different returning methods are beneficial for increasing the nitrogen,phosphorus,and potassium content and yield of rice.Compared with the control,the total nitrogen,phosphorus,and potassium content of rice in F3 treatment increased by 28.16%,19.11%,and 11.67%,respectively,with the most significant improvement.The nitrogen and phosphorus content in different parts of rice at maturity were: spike>leaf>stem,and total potassium content were: stem>leaf>spike.the above-ground dry matter mass of rice in F4 treatment increased by 12.62% to 88.43 g/root.Among the rice yield components,there were no significant differences in thousand grain weight,number of grains per spike and fruit set rate among treatments,while the theoretical yield of rice in F3 and F4 treatments increased by 9.96% and 9.34%,indicating that these two straw returning methods could effectively promote nutrient uptake and utilization by rice plants,increase nutrient accumulation,and thus improve rice yield.Overall,straw returning with the application of decomposing agent to the field has the most significant combined effect on improving soil biochemical properties and increasing rice yield,and is the most suitable return method..