Study on State of Soil Nutrient of Citrus Orchards in Southwest China Demonstration Area of Environmental Immigrants

The results of soil fertility of 92 orchards in the citrus demonstration orchards of Kenfu demonstration plot were as follow:soil fertility on the area was characterized by abundant organic matter,low total nitroge,total phosphorus and potassiun,optimum hydrolyable nitrogen and available phosphorus,and strong acifity.The major nutrient variable coefficient in soil in different citrus orchards are over 16% and pH variable coefficient of the soil is 45%.The citrus orchards of different yield grades showed that the most significant soil chemical characteristic relatives to citrus nutrition seems to the amount of readily hydrolyable nitrogen and available potassium.And that was the restriction factor effect on the improving of the output.As a result,there was an extremely positive correlation between citrus yields and hydrolyable nitrogen and available potassium.Also,the indexes of anundance and shortage of hydrolyable nitrogen and available potassium in soils were put forward in this paper.