Effect of long-term fertilization on the crop utilization of N & P and the ability of supply of available N & P in soil

Based on National Supervision Base for Aqui-cinnamon Soil Fertility and Fertilizer Benefits in Changping,Beijing(1991～2004),the effects of long-term fertilization on fertilizer use efficiency are investigated.The main results obtained are as follows: the total nutrient absorption by crops and apparent nutrient use efficiency(NUE) with combined application of N,P and K are higher than those of the treatment of N only,or NP,NK and PK.Both two treatments of NPK+ organic matter and NPK+ straw are greatly superior to the treatment of those chemical fertilizers alone.Soil available P increases by 11-fold and 5-fold with the treatment of NPK+ organic matter and PK,and 3-fold with NP,NPK + straw and NPK.