Effects Of Straw Returning And Irrigation Methods On Soil Fertility Of Rice

In order to study the changes of soil nutrients in the topsoil layer and the vertical distribution characteristics of soil nutrients in the profile of rice under different straw returning and irrigation methods,eight treatments were set up in this study:No rice and wheat straw returned to the field under conventional irrigation(A),no straw returned to the field under conventional irrigation(B),no straw returned to the field under conventional irrigation(C),no straw returned to the field under conventional irrigation(D),no straw returned to the field under precise irrigation(AW),no straw returned to the field under precise irrigation(BW),no straw returned to the field under precise irrigation(CW),no straw returned to the field under precise irrigation(DW)In order to provide scientific basis for rational utilization of agricultural water and straw resources,the changes of nutrients,soil enzyme activity and crop yield in rice surface soil and one-meter section soil were measured at three different growth stages of rice.The main findings are as follows:1.Under conventional irrigation for two consecutive years,the soil pH of paddy soil under treatment B,C and D decreased compared with that under treatment A,and the nutrients such as organic matter,ammonium nitrogen and available potassium were significantly increased,with the highest growth rate under treatment D.In the first year of precision irrigation,compared with AW treatment,the soil pH of paddy soil under BW,CW and DW treatment increased or decreased,but the soil organic matter,ammonium nitrogen,available potassium and other nutrients contents increased,and the soil nutrient content of DW treatment significantly increased.2.The soil analysis results for 0-100cm paddy field profile showed that under two consecutive years of conventional irrigation,the three straw returning treatment generally reduced soil pH compared with treatment A control;The contents of soil organic matter,ammonium nitrogen and available potassium were increased.In the first year of precise irrigation,compared with AW treatment,the three straw returning treatments generally reduced soil pH and increased soil organic matter,ammonium nitrogen and available potassium contents,and the nutrient contents of DW treatment were significantly higher than those of non-returning rice and wheat straw treatment.In conclusion,both conventional irrigation and precision irrigation had the best effect on improving soil nutrients in rice profile.3.Under conventional irrigation for two consecutive years,compared with treatment A,treatment B,C and D all increased the activities of soil neutral phosphatase,urease,sucrase and catalase,and treatment D had the largest increase rate.In the first year of precision irrigation,compared with AW control,BW,CW and DW treatment all increased the activity of four soil enzymes,and DW treatment increased the most.4.Under conventional irrigation for two consecutive years,compared with the control without straw returning to the field,the rice yield of the three straw returning treatments was increased by 8.70%-13.04%,among which the yield increase of treatment D was the largest.In the first year of precision irrigation,compared with the control without straw returning,BW,CW and DW treatment increased rice yield,with the increase rate ranging from 1.59%to 7.94%,and the increase rate of DW treatment was the largest.In summary,with the increase of experiment years,straw returning and precise irrigation can effectively improve soil nutrient content and soil enzyme activity,and promote crop yield and income.In rice planting,no matter using conventional irrigation or precise irrigation,the technical measures of both rice and wheat straw returning to the field have better soil improvement and yield increase effect.