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化肥施入土壤,真正被作物吸收利用的氮肥约为30～50％(我省目前氮肥中70～80％是碳铵和氨水,其利用率更低),磷肥为10～25％,钾肥也只有40～60％。总之,化肥利用率平均不到50％,老法施肥有一半以上化肥没有发挥作用。另外,国内外普遍反映,同是一定量的某种化肥,其肥效较前降低了。据美国反映,五十年代初,每增施一磅化肥可增产15～20磅玉米,而目前只能增产5磅。我省五十年代初,每斤硫铵可增产近10斤稻谷,六十年代中期降至3～4斤,而到七十年代后期则更降至2斤左右了。
Fertilizers applied to the soil, the actual nitrogen fertilizer absorbed by the crop is about 30 ~ 50% (70-80% of our current nitrogen fertilizer is ammonium bicarbonate and ammonia, the utilization rate is lower), phosphate fertilizer is 10 to 25%, potassium fertilizer Only 40 ~ 60%. In short, the average utilization of chemical fertilizers is less than 50%, and over half of the fertilizers of the old method failed to play a role. In addition, generally reflected at home and abroad, with a certain amount of a certain amount of chemical fertilizer, its fertilizer efficiency lower than before. According to the U.S. reports, in the early 1950s, 15 pounds to 20 pounds of corn could be increased for every additional kilogram of fertilizer produced, and at present, only 5 pounds can be increased. At the beginning of 1950s in our province, ammonium sulfate per kilogram could increase rice production by nearly 10 kilograms, down to 3-4 kilos in the mid-1960s, and down to 2 kilos by the late 1970s.