氮钾肥配施对水稻产量和养分平衡的效应

水稻对氮钾两元素的需要要相近。为保持土壤养分平衡,氮钾肥配施比例似以1:1为宜;但为了提高当季作物施钾的增产效应,氮钾配比可乐用1:0.4～0.5。水稻地上部和地下部的协调生长受到氮钾肥配比的影响:N>K,有利于地上部生长;K>N,则有利于地下部生长。过量施氮对根系生长不利。氮钾供应状况影响稻株中的养分平衡,提高氮钾施用水平,稻株中氮钾的浓度随之提高,但钙镁的浓度下降,钾镁的拮抗作用尤为明显。

EFFECTS OF COMBINED NITROGEN-POTASSIUM FERTILIZATION ON THE YIELD AND NUTRIENT BALANCE OF RICE

To establish the effect of N-K application on yield and nutrient balance of rice, six field experiments and two pot tests were carried out at different sites in Fujian Province during 1982-85. Effects of N×K interactions on the plant growth and nutrient uptake of rice was also investigated. The results are as follows: 1. Equal amounts of nitrogen and potassium were absorbed by the rice plant. In order to maintain the nitrogen-potassium balance in the soil, equal dose of N and K_2O should be applied. In case of soil potassium deficiency, N-K_2O application at the ratio of 1: 0.4-0.5 still can increase the rice yield. It appears that one unit of potassium will combine with two units of nitrogen. 2. The effect of N and K application on S/R ratio showed that when N>K, S/R ratio increased, but when K>N, S/R ratio decreased. The yield of dry shoot increased with nitrogen dressing only in the presence of adequate potassium. Excessive nitrogen was no favorable for root development, even with increasing potassium to antagonize it. 3. The mineral nutrient balance in the rice plant was also influenced by N/K ratio and the amount of both nutrients. Increasing N,K supply promoted the amounts of N, K content in the shoot,but depressed the uptake rate of Ca, Mg. This is especially eminent in the antagonistic effect of K on Mg.