THE NITROGEN FERTILIZER UTILIZATION AND NITROGEN BALANCE BY WINTER WHEAT IN SANDY SOIL

The effects of different fertilization stage on wheat yield,nitrogen uptake,utilization,residue,distribution and nitrogen balance were studied by potted plant experiment.The results showed that the highest yield obtained appeared in the treatment of topdressing on shooting age when 1/2 nitrogen fertilizer applied as base fertilizer.Topdressing on earning stage reached higher yield than that on regreening stage on the case of lower nitrogen applied.There was no difference between these two treatments if higher nitrogen applied.Nitrogen plant uptake in 1/2 nitrogen as topdressing treatment was significantly higher than that of all as base fertilizer,which mainly because of improved efficiency of nitrogen fertilizer.31.7%～66.8% of residue nitrogen in soil was distriubuted in 0～40 cm soil layer after harvest and proportion of residue nitrogen in this layer was increased when nitrogen fertilizer applied later.However,in hte treatmet of all nitrogen applied as base fertilizer and topdressing on regreening stage,proportion of residue nitrogen in the subsoil was higher than topduressing in later state,which in 80～100 cm depth was even exceeded that in the topsoil.