The Effects Of Different Modifiers On Soil Water Salt And Nutrient Transport Under Straw Coverage

Soil degradation is serious in the black soil area of Northeast China,which hinders the efficient and sustainable utilization of soil resources and the sustainable development of agriculture.Straw mulching and application of soil ameliorants are beneficial to improve soil physical and chemical properties in black soil area and maintain soil efficient and sustainable development.Conditioner for straw mulching conditions,application of the optimal model,based on the heilongjiang province Harbin xiangyang farm black soil as the research object,under the condition of straw mulching,adding humic acid(FZ)respectively,rice husk carbon(DC),peat(CT)and pine bark(SP)four soil conditioner,based on the data of laboratory test,analyze and study the characteristics of soil water,salt and nutrient transport under the action of different amendments,reveal the influence mechanism of different amendments on soil water,salt and nutrient transport under the condition of straw mulch,and put forward the appropriate soil amendments and application amount under the condition of straw mulch.In order to provide reference and basis for efficient utilization of straw resources,rational utilization of soil amendments and improvement of soil resources in black soil area.The research mainly draws the following conclusions:(1)Four kinds of modifier can improve the performance and soil water infiltration performance,including CT saturated hydraulic conductivity and the most significant effect of the wetting front migration velocity,saturated hydraulic conductivity and the wetting front migration velocity increases with the increase of applying CT content,SP increased cumulative infiltration amount and the maximum average infiltration rate,cumulative infiltration volume with increased first and then applying SP content,The average infiltration rate had no obvious change with the increase of SP dosage.Compared to DC and FZ decreases after irrigation,soil moisture content of SP and DC will increase after irrigation,soil moisture content and FZ dealing with soil moisture content on CT also increases with its seems did not show obvious regularity,SP with soil moisture content present a tendency of increasing with the increase of applying SP content,DC treatment of soil moisture content with the increase of applying DC content first increased then decreased;Kostiakov model with straw mulch and different modifiers has higher fitting accuracy than Philip model for soil infiltration process.(2)Except SP,the other three ameliorants can inhibit soil moisture evaporation and increase soil moisture content after evaporation,among which the cumulative evaporation of CT is the least and the soil moisture content after evaporation is the highest.The cumulative evaporation show a downward trend with the increase of the application amount of CT,while the soil moisture content after evaporation increased with the increase of the application amount of CT.Black model fit the soil evaporation process with different modifiers under straw mulching condition with higher accuracy than Rose model.(3)Except for DC,all the other three amendments can reduce the soil p H value,and CT reduce the soil p H value the most.With the increase of the application amount of CT,the soil p H value decrease gradually.All the four amendments can increase the soil salt content,and FZ increase the soil salt content the most,and the soil salt content increase with the increase of the application amount of FZ.The relationship between soil salt content and the amount of amendments,soil depth and irrigation amount was linear.(4)All treatments except CT10,CT25,SP10 and SP20 increase soil available P content,and all treatments except SP10-SP30 increase soil ammonia N content,among which FZ increased soil available P and ammonia N content the most,and soil available P content increase with the increase of FZ application amount.The content of ammonium nitrogen in soil firstly increase and then decrease with the application amount of FZ.There is a power function relationship between the application amount of CT,SP,FZ and available phosphorus,and a quadratic function relationship between the application amount of DC and available phosphorus.There is a power function relationship between the application amount of CT,SP,DC and ammonium nitrogen,and a quadratic function relationship between the application amount of FZ and ammonium nitrogen.(5)The comprehensive index method is used to evaluate the soil water,salt and nutrients under the conditions of straw mulching and applying different modifiers.The results show that CT25 had the highest comprehensive effect evaluation index(0.673).Under the strew mulching condition,the optimal soil conditioner is peat,and the optimal application amount was 25g/kg.