Study On The Different Fertilizer Rate And Rainfall Intensity Of Nitrogen Loss Characteristics In The Process Of Non-Point Source Pollution

In recent years, with the economic growth, China has invested more and more fertilizer in agriculture, and has been the first in the world. Excessive fertilizer application causes a large amount of chemical fertilizers to accumulate in plants and soil, in the case of rainfall, resulting non-point source pollution through underground water seepage and surface runoff. Non-point source pollution is widely distributed in our country, but it is very difficult to control, so people have to pay attention to the management of non-point source pollution.Going through massive information and researches at home and abroad, finally find the main factor to cause non-point source pollution is unreasonable and excessive application of chemical fertilizer. This paper designed a simulation experimental plot, using the rainforest spray system and artificial rainfall simulation method. This thesis study in the following aspects:(1) study on the different fertilizer dosage to nitrogen loss characteristics in non-point source pollutionIn the case of rainfall intensity is moderate, designed four different fertilizer levels experiment, and collected surface runoff water and leak water at 15cm,30cm respectively in the soil to do experiment analysis. In this experiment fertilized three times, and sampled after the second and third fertilization, then analyzed the total nitrogen, ammonia nitrogen, nitrate nitrogen, nitrite nitrogen and other indicators to study the nitrogen loss characteristics in surface runoff water and underground water seepage. The experiment showed that:the total nitrogen, ammonia nitrogen, nitrate nitrogen and nitrite nitrogen concentration in four fertilizer levels experimental group was more fertilizer group> moderate fertilizer group> less fertilizer group> no fertilizer group. Therefore, the total nitrogen, ammonia nitrogen, nitrite nitrogen, nitrate nitrogen concentration and fertilizer dosage into positive correlation, that is, the more fertilizer dosage, the higher corresponding concentration.(2) study on the different rainfall intensity to nitrogen loss characteristics in non-point source pollutionIn the case of moderate fertilization, three experiment groups of different rainfall intensity was designed and collected surface runoff water and leak water in the soil depth of 15cm,30cm respectively to do experiment analysis. In this experiment fertilized three times, and sampled after the second and third fertilization, then analyzed the total nitrogen, ammonia nitrogen, nitrate nitrogen, nitrite nitrogen and other indicators to study the nitrogen loss characteristics in surface runoff water and underground water seepage. The experiment showed that:the total nitrogen and ammonia nitrogen concentration of surface runoff water and underground water seepage in three different rainfall intensity was heavy rain group> moderate rain group> light rain group. Therefore, the concentration of total nitrogen and ammonia nitrogen are positively related with rainfall intensity. Namely, when the rainfall intensity is bigger, the relative concentration is higher. However, the concentration of nitrite nitrogen and nitrate nitrogen in surface water and underground water seepage did not show significant positive correlation with rainfall intensity.(3) No matter under what condition of rainfall and fertilizer, the concentration of total nitrogen, nitrate nitrogen and nitrite nitrogen in the soil depth of 30 cm> the soil depth of 15 cm> the soil depth of 0 cm. The highest concentration of total nitrogen, nitrate nitrogen and nitrite nitrogen appeared in the underlying soil, which showed that the concentration of total nitrogen, nitrate nitrogen and nitrite nitrogen showed increasing downward distribution characteristics along with the increase of soil depth. The concentration of ammonia nitrogen in the soil depth of 0 cm> the soil depth of 15 cm> the soil depth of 30 cm, and the highest concentrations of ammonia nitrogen appeared in surface soil, which showed that with the increase of soil depth, the concentration of ammonia nitrogen presented decline down distribution characteristics.