Nitrogen And Phosphorus Loss Characteristics Of Slope Orchard In Different Measures Under Natural Rainfall Condition

Nitrogen and phosphorus loss of soil is an important form of agriculturalnon-point pollution, and the main source of water eutrophication. Serious soil andwater loss of red slope orchard,caused by climate and unreasonable use, has induceddegeneration of the eco-environment and soil fertility, seriously restricted thesustainable development of agriculture and social economy．In this thesis, with the way of runoff plots, we designed six different measureswhich respectively were cleaning bench terrace tillage, level bench terrace Ⅰ, levelbench terrace Ⅱ, whole covering, strip covering and cleaning tillage, and studied thelosses of runoff, sediment and N,P. Then by chosen two typical rainstorms, weanalyzed the loss characteristics of runoff, sediment and N,P of different plots.Meanwhile, discussing the effects of runoff condition and different measures on theloss characteristics. The main results obtained in this study are as follows:(1) During2009-2011, the study of rainfall condition and the loss of runoff andsediment showed that, the more the rain capacity, the more the loss of runoff andsediment; During the peak rain month, the situation of nitrogen and phosphorus lossexpressed that, the more the rain capacity, the more nitrogen and phosphorus loss. Themain reason of runoff, sediment, nitrogen and phosphorus loss was the amount of raincapacity.(2) The loss of runoff, sediment, nitrogen and phosphorus caused by cleaningtillage was the most serious, there were different degree of loss in other five plots. Itmeant biological measure, engineering measure and biological combined withengineering measure could reduce the loss effectively.(3)Under the typical natural rainfall condition in the south, the loss of runoff andsediment in the early runoff was the most serious in six plots, and it had a generallydowntrend along with runoff, tending to stable at final phase, which was caused bythe increase of rainfall intensity and rain capacity; Runoff was the major way of theloss of N and P, results showed that the majority loss of TN, NH4+-N, NO3--N and TPgathered largely at the beginning of runoff, tended to down slowly along with rain,and stabled in finally, which was caused by the increase of runoff. Sediment was theanother cause for nutrient loss, and the loss of total nitrogen, available nitrogen, totalphosphorus and available phosphorus gathered largely at the beginning of runoff,tended to down slowly along with rain, and stabled in finally, which was caused bythe increase of sediment and nutrient enrichment rate in sediment.