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郊区自1964年大面积发展麦一稻一稻三熟制以来,粮食年亩产增至1600斤左右,皮棉亩产130斤左右,粮田复种指数240％左右。因此,对土壤养分平衡及地力培养问题,已日益引起人们的重视。而不同耕作制度下土壤钾素的收支平衡状况,是合理施用钾肥的重要依据。本文根据若干田间试验资料,就三熟制下土壤钾素的平衡和供钾力问题,提供若干素材。上海平原位于长江三角洲出口处,土壤母质系长江上游石灰性冲积物,较均一,含有较丰富的云母类含钾矿物和一定数量固钾
Since the large-scale development of the wheat-rice-rice-three-crop system in the suburbs in 1964, the annual output of grain has increased to about 1,600 kg per mu, about 130 kg per mu for cotton and about 240 percent for the multi-crop of grain fields. Therefore, the problem of soil nutrient balance and soil fertility cultivation has drawn more and more attention. However, under different tillage systems, soil potassium balance of payments is an important basis for the rational application of potash fertilizer. Based on a number of field trials, this paper provides several materials on the balance of soil potassium and potassium supply under the three-cropping system. The Shanghai Plain is located at the exit of the Yangtze River Delta. The soil parent material is calcified alluvial deposits in the upper reaches of the Yangtze River. It is relatively homogeneous and contains abundant mica-containing potassium minerals and a certain amount of potassium