A Research Of The Black Soil Slope Surface Nutrients Loss In The Conditions Of Simulated Rainfall

The black soil is one of the most fertile soil types in China,and the soil erosion in black soil area is becoming more and more serious.Under the condition of heavy rainfall or unreasonable irrigation,the soil nutrients of the black soil slope are prone to loss of soil nutrients,and land productivity is decreased,which leads to food security and environmental deterioration.Therefore,it is very important to explore the mechanism of soil nutrient loss in black soil area,and to better protect the black soil resources in china.In this study,access to relevant information,grasp the nature of our country,the black soil analysis based on the results of scientific research,using interior artificial rainfall simulation test method,test method,studied in the discussion and detailed,soil bulk density,rainfall duration,fertilization three different influencing factors,soil,slope nutrient(Nitrate nitrogen,available phosphorus and available potassium)migration,loss characteristics,further reveals the mechanism of agricultural non-point source pollution,it also provides scientific basis and technical support for the control and prevention of soil nutrient loss,and the establishment of soil nutrient loss of slope for Northeast Black Soil model.The main conclusions of this paper are as follows:(1)the effect of soil bulk density on soil nutrient loss in black soil slopeWith the increase of soil bulk density,runoff coefficient becomes more and more larger,the runoff time become earlier,the infiltration rate decreases,the nitrate nitrogen loss increases,and the runoff concentration increases at the same time.However,the loss of available phosphorus and Available potassium are different from that of nitrate nitrogen.The soil bulk density variation in 0.8?1.3g/cm3,with the increase of the bulk density,The concentration of available P and available K in 20min water sample before runoff was increased,but within 20?60 min,solute concentration content due to soil surface erosion and gully erosion and with the density change in opposite direction.When the bulk density increased to 1.4 g/cm3,the concentration of phosphorus and potassium ions decreased.The wetting front depth of soil layer becomes shallower with the increase of soil bulk density.When the bulk density is 0.8 g/cm3,the wetting front can reach to 15 cm,and the bulk density is only about 1.4 g/cm3,and it can only be leached to the surface of 11 cm deep.lt is found that the power function is a model which is suitable to simulate the change process of solute loss in black soil region.(2)the effect of rainfall duration on nutrient loss in black soil slopeThe black soil non saturated soil under the condition of study on the migration of nutrients,results show that during rainfall,rainfall duration is longer,soil nutrient loss is more serious,the cumulative runoff and sediment and rainfall duration increase linearly.The rainfall duration varied from 30 to 90 min,with the increase of rainfall duration,reduce soil nutrient content,after 20 min gradually stabilized,when rainfall duration increased to 120 min,the nitrate nitrogen content changed little,while phosphorus and potassium ions solute content increased,phosphorus ion increased with potassium ion is more obvious than.With the increase of rainfall duration,the peak value of phosphorus ion and potassium ion changed little,mostly in the surface soil of 10 cm,while the nitrate nitrogen concentration increased gradually.30,60,90 and 120 min after the rainfall,the concentration of nitrate nitrogen in soil respectively 7,8,10 and 14 cm;the soil moist peak with rainfall duration increased,respectively in the soil under 10,12,16 and 19 cm,The rainfall after 120 min soil layer all wet.(3)the effect of Fertilization on nutrient loss on the slope of black soilUnder the five different soil bulk density,surface spraying and mixed application have no significant effect on runoff yield and runoff.The fertilization methods have a significant effect on the concentration of N,P and K in runoff.Regardless of soil bulk density increases or decreases,initial solute concentration in runoff,surface spraying is much higher than that of the corresponding mixed fertilizer treatment,five kinds of nitrate under the condition of different density of surface runoff in Spraying Nitrogen and soluble phosphorus and potassium concentrations were initial runoff when the corresponding mixed fertilizer treatment 2.6-3.2,and 2.1-2.6 1.7-2.1 times.From the point of view of the total nutrient loss,the nitrate nitrogen loss in the same bulk density under the conditions of surface spraying is mixed 9?11 times the soluble phosphorus loss in surface spraying condition is mixed between 7?10 times the potassium loss in 3?6 times.With the increase of soil bulk density,the difference of nitrate nitrogen and potassium ion loss between the two spraying methods of surface spraying and mixed application was reduced,while the difference of phosphorus loss was increased.When the soil bulk density was less than 1.2 g/cm3,the most fitting coefficient of surface power function was higher than that of mixed application.When the soil bulk density was greater than or equal to 1.2 g/cm3,the coefficient of mixed application was higher than that of surface spraying.