Abstract:

There have been many reports about the requirements of nitrogen, phosphorus and potassium in grain maize, but seldom in ensilage maize. The objectives of this research were to compare the N,P,K requirements among grain maize,grain-forage maize and ensilage maize, and to provide a guide of fertilizer application for high yielding and high effective cultivation of ensilage maize.The N,P₂O₅ and K₂O contents absorption and accumulation amounts and absorption ratio in the plants were measured and the results showed that nitrogen and phosphorus contents in ensilage maize were different from that in grain maize.The nitrogen contents of ensilage maize showed a unimodal curve during the growing stage,and reached the maximum at 55 d after seedling emergence.The phosphorus contents were relatively stable,and the potassium contents decreased gradually in the process of growth.The ensilage maize required more nitrogen, phosphorus and especially more potassium than grain-forage maize.The suitable fertilization ration was N︰P₂O₅︰K₂O=(2.74±0.14)︰1︰(5.94±0.82), and the demands for N, P₂O₅ and K₂O per 100 kg dry matter produced were (0.57±0.05) kg, (0.26±0.03) kg and (1.58±0.12) kg, respectively. The demand of N and P₂O₅ per 100 kg dry matter was grain maize cultivar＞grain-forage maize cultivar＞ensilage maize cultivar, and that of K₂O was ensilage maize cultivar＞grain-forage maize cultivar＞grain maize cultivar.It indicates that ensilage maize has higher dry matter production efficency.

Key words: Phosphorus, Potassium