Study on Limiting Factors of Soil Nutrient in Xinjiang Cotton Field

Cultivated layer soil samples were collected in 21 plots from main soil types in 4 cotton production areas in Xinjiang.Based on the results of the soil samples analysis,soil adsorbing trials and pot experiments by systematic approach,the variance of soil nutrient elements,limiting factors of soil nutrient and benefits of nitrogen,phosphorus and potassium were studied on these soil types in 1996～2002.The main results are as follows:nitrogen is the first limiting factor,phosphorus is the second limiting factor,potassium and zinc are limiting factors or latent limiting factors,boron and manganese have not same effect in different areas,so the scarce order of main soil nutrient is NPKZnB Mn in Xinjiang cotton field.The benefits of nitrogen,phosphorus and potassium were 1.62 kg/kgN,1.85 kg/kgP_2O_5 and 2.71 kg/kgK_2O respectively.