Effect Of Rice Straw Retention On Soil Chemical Properties And Content Of Nitrogen And Phosphorus In Runoff

Straw generally refers to the remaining parts of crops after harvest.Returning to the field scientifically and reasonably can improve soil structure,increase soil fertility,and benefit soil and water conservation in the field.The effects of different returning methods on soil and runoff are also different.In this paper,the effects of rice straw on soil nutrient and nitrogen and phosphorus content in field runoff were studied by field experiment.The following findings emerged:(1)Three different treatments under Straw Returning: A4 full amount of soil returning to soil + conventional constant fertilization,A5 straw full amount of soil returning to soil + conventional reduction fertilizer 15%,and A6 straw natural stacking returning to field + regular reduction fertilization 15% can increase the content of soil alkaline nitrogen,total nitrogen and available phosphorus,and the effect on total phosphorus is not obvious.Compared with the natural stacking and returning to field,the total amount of straw mulching and returning to field increased the soil total nitrogen,total nitrogen and available phosphorus.A3 no straw returning to field + conventional fertilization and A1 no straw returning no fertilizer,A2 full soil+ soil + no fertilization and A4 full amount of soil + conventional fertilization,the two groups showed that fertilizer could significantly increase the soil nutrient content.(2)The three treatments of straw returning to the field,including full amount of A4 and conventional fertilization,full amount of A4 straw mulching soil returning to field+ 15% of conventional fertilization,and A6 straw natural stacking to field + regular reduction fertilization 15% compared with no straw returning can significantly increase the content of organic matter in soil,but there is no significant difference between A5 full soil returning and A6 stacking to the field.Two different ways of returning farmland had no obvious effect on soil organic matter content.A3 no straw returning and conventional fertilization compared A1 blank group,A2 overlying soil returning field + no fertilization compared with A4 overlying soil and conventional fertilization,indicating that fertilizer application could significantly increase soil organic matter content.(3)The total nitrogen loss in the field surface runoff was obviously reduced by two kinds of A4 full soil covering and A6 stacking and returning to the field,and the amount of total nitrogen in runoff could be reduced by reducing the amount of fertilizer.The reduction of total nitrogen content was between 7.41%-21.78%.Themain loss form of nitrogen in runoff is ammonium nitrogen,and its concentration is about 3 times that of nitrate nitrogen.In all treatments,A5 reduction of 15% fertilizer could reduce nitrate concentration in runoff.A4 total soil covering and field fertilization could effectively reduce ammonium nitrogen loss.(4)In this experiment,there was no significant effect on the loss of total phosphorus in the runoff with the full amount of A5 overlying soil and conventional reduction of 15% fertilizer.The total phosphorus loss in the runoff was significantly reduced by the full amount of A4 overlying soil returning and the returning of the two kinds of returning fields by A6 stacking to the field.The main forms of phosphorus loss in runoff were particulate phosphorus,and soluble phosphorus accounted for only about 20% of the total loss of total phosphorus.The reduction of soluble phosphorus by A4 and A5 reduced to 15% of the runoff was between 18.06%-35.07% and28.74%-50.71%.