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试验表明在土壤速效磷钾中低水平时,种植水稻连续三年单施氮肥肥效明显趋于下降。配施磷钾化肥使每公斤N多增产稻谷1.7公斤,尿素利用率提高5.2—6.1%,而磷钾肥肥效有逐年上升的趋势,氯化钾利用率提高7.1%。富磷及中、缺钾土壤,种植水稻连续五年不施用磷钾肥,土壤速效P_2O_6含量下降15.0—16.2ppm,速效K_2O下降17.2—17.7ppm。在施用较高量氮肥,氮磷钾施肥比例为N:P_2O_6:K_2O=1:0.5:1,土壤速效磷提高27.3—28.2ppm,高产壤质粘土及中产砂质粘壤土速效钾无明显变化。
Experiments show that in the soil at the low level of available phosphorus and potassium, planting rice three consecutive years of nitrogen fertilizer efficiency significantly decreased. With phosphorus and potassium fertilizers so that more than 1 kg per kilogram of N yield more rice 1.7 kg, Urea utilization increased by 5.2-6.1%, while the phosphorus and potassium fertilizer efficiency year by year upward trend, utilization of potassium chloride increased by 7.1%. Phosphate-rich and potassium-deficient soils, rice and paddy rice were not applied with P and K fertilizer for five years in succession. The available P_2O_6 content in soil decreased by 15.0-16.2ppm and the available K_2O decreased by 17.2-17.7ppm. In the application of higher nitrogen fertilizer, N, P_2O_6: K_2O = 1: 0.5: 1, soil available P increased by 27.3-28.2ppm. There was no significant change of available potassium in high yield loamy clay and middle sandy loam.