Study On Nitrogen And Phosphorus Losses From Field Used Manure In Dianchi Watershed By Simulated Rainfall Method

Nitrogen and phosphorus losses from farmland have been identified as one of important causative factors for agricultural non-point source pollution. There has a number of researches about the nitrogen and phosphorus losses from manure overseas, while it's rare at home, especially about field in-situ studies. Aimed at the characters of the abundance of manure, the high level of utility quantity, the more chances to occur the phenomenon of water and fertilizer coupling and etc, Field in-situ trials were carried out which based on the collection, tidying, and analysis of investigation data such as rainfall data, planting types, fertilization status and ect. to study the effects of different amount of swine manure application on nitrogen and phosphorous losses characteristics from different crop type's farmland under rainfall simulation in Dianchi watershed of Yunnan province. Main results are showed as follows:Under the condition of 80mm-depth rainfall, there are not apparent differences between surface runoff occupying 59.17% and leakage occupying 53.52% of the rainfall. By the way of leakage, the interval between the time to produce loss and the time to fall is half of an hour. The average time of the whole to produce loss is 93.41mins; the velocity of producing loss is slow with a average of 35.98ml per min. While by the way of surface runoff, the interval between the time to produce loss and the time to fall is just about a quarter of an hour; the whole time to produce loss short, of which the average time is 32.23mins.The velocity of producing loss is fast with a average of 94.79ml per min. However, there are not apparent difference between the two type of loss with different dosages of organic manure and planting types.The concentrations of nitrate nitrogen, ammonium nitrogen, total dissolved nitrogen, total nitrogen, dissolved reactive phosphorus and water-soluble total phosphorus in leakage liquid and runoff liquid at the same place were positively correlated with amount of swine manure application respectively. The concentrations of nitrogen and phosphorus in runoff water is higher than that in infiltrated water. Surface runoff is the main way of nitrogen and phosphorus losses under the condition.Under both types of losses, the dissolved nitrogen was the main loss forms, of which the average occupies more than 60% of the total loss consistence. Without the application of manure, the inorganic nitrogen is the main pattern of the water-solution nitrogen loss, occupying about 60%. With the application of the organic manure, the organic nitrogen is the main pattern of the water-solution nitrogen loss, of which the average occupies more than 60-70%.By way of leakage, particulate phosphorus was the main loss forms when the amounts of swine manure application from 0 to 15 ton per hm square. Dissolved reactive phosphorus is the main loss forms when the amounts of swine manure application from 30 to 150 ton per hm square. Under both types of losses, The water-soluble inorganic phosphorus was the main loss form of dissolved phosphorus, of which the average occupies 67.54%.A11 forms of loss were not correlated with amount of swine manure application and difference of sites.The losses of total dissolved nitrogen, total nitrogen, dissolved and water-soluble total phosphorus from runoff and leaching at the same place were positively correlated with amount of swine manure application respectively. The losses from runoff were higher than that from leaching. When amount of swine manure application is equivalent the farmlands with different planting types have differences in concentration of nitrogen. The generally trend is shown as vegetable farmland＞flower farmlands＞crop farmland.