灌淤土是银川灌区的主要耕作土壤,它是在人类长期进行灌溉、耕作、种植与施肥等因素作用下形成的。而普通灌淤土是受这些因素影响最久、成土过程最深刻、熟化程度最高的灌淤土类型。普通灌淤土的肥力水平,在其它条件相同时,受有机质含量高低的影响;土壤中氮素形态又以有机态为主,占90％左右,故土壤中全氮量的高低,又受有机质含量的 Irrigation silt is the main farming soil in Yinchuan irrigation area. It is formed under long-term irrigation, farming, planting and fertilizing. Ordinary irrigated soil is affected by these factors the longest, the deepest soil into the process, the highest degree of curing irrigated soil type. The fertility level of ordinary irrigated silt soil is affected by the content of organic matter under the same conditions. The nitrogen forms in soils are mainly organic, accounting for about 90%, so the total nitrogen content in soils is affected by organic matter Content