Abstract:The peak output of rice can be calculated from the basic fertility of soil with an equation proposed by the authors.In this paper,an additional equation to calculate the requirement of N for the predicted maximum yield of rice are proposed as follows:
NR=(0.018(Y-1.05X)/EF
where X is the yield of rice on certain rice field without fertilization,Y,the maximum obtainable yield of rice on the same field well fertilized.N,nitrogen requirement for yield Y,Er,efficiency of the fertilizer applied.Experiments has shown that the eqation a practicable.