EFFECTS OF MODELS OF APPLYING NITROGEN FERTILIZER ON NUTRITION ACCUMULATION OF SPRING MAIZE

A field experiment was conducted to study effects of nitrogen(N) fertilization modes on nutrients accumulation in spring maize,aimed to supply technical supports for spring maize fertilization.Nitrogen fertilization had obviously positive effect on improvement of maize dry matter and its N,phosphorous(P),and potassium(K),especially at the growth stages after jointing.With maize growing,the accumulation amounts of dry matter and N,P,and K all increased,but the increment differed,being smaller before tasselling stage and larger after tasselling stage for dry matter and N and P,while being adverse for K,suggesting that early growth stages were the key period for K uptake by maize plant,and later growth stages were the key period for N and P uptake.Different N fertilization modes had lesser effects on dry matter accumulation,but complicated effects on N,P,and K accumulation.Compared with other N fertilization modes,both two top fertilizer dressings mode and one deep fertilizer application mode showed predominance on N,P,and K accumulation amounts,output-input ratio,fertilizer N agronomic efficiency,and fertilizer N use efficiency.Considering the nutrient requirement characteristics of maize and the properties of chemical fertilizers to be applied,it suggested that basal-dressing P and K fertilizers in combining with one deep-application of N or top-dressing N at jointing and tasselling stages would be the effective fertilization modes of chemical fertilizers for spring maize in Northeast of China