Stydy on fertilization model of varied farmland ecological systems of different precipitation years in southern mountain of Ningxia

The paper apply design of regression saturation to make long term experiment on rates of nitrogen and phosphorus affecting spring wheat production in three kinds of different farmland ecological systems. The effect equation of fertilization of spring wheat is put up, and the equation is analyzed. The plan of fertilization of the biggest production and the optimum economic effect are defined, and the sequence of fertilizer and the relation of high?production and fertilization are defined.