DYNAMICS OF BIOMASS AND ITS COMPONENTS AND MODELS OF NUTRIENTS ABSORPTION BY SPRING MAIZE UNDER DIFFERENT NITROGEN,PHOSPHOROUS AND POTASSIUM APPLICATION RATES

A field experiment was conducted to analyse the dynamics of biomass yieldand its components(grain and vegetative yield and N,P and K absorption by springmaize under dlfferent N,P and K application rates. The results indicated that thedynamic biomass yield and grain weight could be described by Logistic curve equation,and that of vegetative yield by regression equation Y=axebx. Biomass yieldY was afunctlon of grain yield x1 and vegetative yieldx2, as described by regression equationof Y=exp(a+b1x1b2x2. The increasing duration and increasing rate of biomass yield andgrain weight, and the increasing duration of vegetative yield and its decreasing ratewere obviously influenced by different N,P and K application rates. Rational ratio ofNPK and their appropriate application methods not only accelerate the accumulation oftotal biomass in earlier growth stage, but also stimulated the rapid transformation ofvegetative dry matter to grain in later growth stage, resulting in high yields. Theaccumulation of N,P and K in spring maize under different NPK application rates couldbe described by Logistic curve equation. The highest nutrients absorption rates(HAR) andthe time of HAR in maize were obviously influenced by different NPK application rates.High HAR and an earlier time of HAR could be achieved with proper NPK applicationrates. The amount of N, P and K absorbed by maize plants for the production of 100 kgmaize grain were 1. 557~1. 602kg, 0. 419~0. 427kg and 0. 973~ 1. 025kg. respectively.with a ratio of N:P:K 1: 0. 27: 0. 62~0. 64.