The Study Of Characteristics Of Nitrogen Loss In Agricultural Non-point Pollution In Different Soil Types And Different Rainfall Intensity

Since the 80s of last century,China has realized the chemicalization of agriculture in just a few decades.The heavy use of chemical fertilizers plays an important role in grain production and food security in China.But due to the excessive use of fertilizer and backwardness of application technology,effective use rate of fertilizer is generally low.Excessive nutrient causes serious agricultural non-point source pollution.Sichuan is a major agricultural province in China,and at the same time,Sichuan province is an important ecological barrier of upper reaches of China's Yangtze River,as well as the important water conservation district and recharge area.The prevention and control of agricultural non-point source pollution in Sichuan has important significance in improving China's water environment quality,and promoting the healthy development of China's agricultural economy.This topic researches on the characteristics of nitrogen loss in the underground water and surface runoff on conditions of different soil types and different rainfall intensity,through the experimental platform of "water spray system + vegetables + surface runoff and underground water collection devices",in order to provide decision reference for the prevention and control of agricultural non-point source pollution in Sichuan,which varies from time to time and place to place.Firstly,efforts were made to analyze effects of different soil types on nitrogen loss,with three common soil types in Sichuan area:paddy soil,purple soil and yellow soil.Through the experimental study,it was indicated that on the same conditions of moderate rainfall intensity,the nitrogen loss rate in purple soil was the highest,reaching 3.67%,so as to the loss speed,it can be inferred that nitrogen loses easily in the case of increased artificial fertilization.The nitrogen retention capacity of paddy soil was the strongest,the nitrogen loss rate was 1.73%,and the loss speed was slow;While the nitrogen loss rate of yellow soil was as low as 1.49%,but due to the high nitrogen content of yellow soil itself,the amount of nitrogen loss was the largest.Secondly,for the changeable weather conditions in Sichuan province,efforts were made to analyze the influence of different kinds of rainfall intensity on nitrogen loss in light rain,moderate rain and heavy rain.Through the experimental study,it was found that under the condition of paddy soil,the nitrogen loss rate in light rain,moderate rain and heavy rain was 0.93%,1.79%and 2.37%,respectively.The loss of nitrogen increased sharply with the increase of rainfall intensity.The rainfall intensity was the greatest impact of the loss of ammonia nitrogen,the ammonia nitrogen loss under heavy rain was 685.10mg,accounting for 35.13%of the amount of ammonia fertilizer applied,while the intensity of light rain was only under the value of 8.19%.It was found in the experimental study that the nitrogen lost mainly through the underground water both under different rainfall intensity and different types of soil.The ammonia nitrogen is the main form of nitrogen loss in surface runoff,and the nitrate nitrogen is the main form of nitrogen loss in the underground water.