In light of current using situation and drawing on the experience of many scholars researched methods and viewpoints , this thesis made com land , fallow land , orchard , grass land as experimental field in black soil region jlau , which carried out experiment by applying different amounts of n and p fertilization in corn field . by means of collecting the samples of rainfall runoff , erosion silt and surface layer soil before and after rainfall for one year nature precipitation in field , we study the effect of surface runoff on n and p nutrient and fertility degeneration . the results showed : ( l ) there are lots of factors which affect soil erosion and losses of n and p , in which rainfall and rainfall intensity were more important , while rainfall intensity is the most important meteorological phenomena factor 针对当前黑土利用现状，本文借鉴众多学者的研究方法和观点，在吉林农大黑土区选择利用方式不同的玉米地、休闲地、果园、草地，在玉米区进行了不同数量的施肥，通过野外试验，采集一年自然降雨产流及泥沙样品，同时采集降雨前后的耕层土壤样品，研究了黑土区地表径流对氮磷养分特征及肥力退化的影响，结果表明：土壤侵蚀和氮磷的流失受诸多因素的影响，降雨量、降雨强度是重要因子，而降雨强度是影响农田地表径流养分流失的最重要的气象因子，特别是暴雨，暴雨径流中氮磷浓度较平时高得多；随作物生长，覆盖度逐渐增加以及不同利用方式下表现的覆盖度差异，氮磷流失都表现为显著的差异。
The latter will be given options and allowed time to try them out , which is long enough for at least one test interval . people will not jump rashly to the conclusion that something must be wrong out there , and the experimenters will not be under pressure . such experimental fields are meant to find out where shortcomings are and what can be done as a remedy 在试验田里大家包括媒体允许试验者出错,给他建议给他时间,而这个时间一定是一个试验周期的时间,看官千万不要一语定性,加以否定,造成试验者承受巨大的舆论压力,因为开辟试验田就是以找出不足,加以改进为目的的。
