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通过分析江苏省如皋市1982年~2002年耕层土壤速效钾含量,研究了农田土壤速效钾时空变化及水稻钾肥适宜用量。结果表明,20年间该市耕层土壤速效钾含量已发生明显变化。2002年含量仅为50.51mg kg-1,比1982年降低了5.5mg kg-1,降低9.80%。耕地速效钾含量分级已从20年前的以Ⅳ、Ⅴ为级为主转变为Ⅳ、Ⅴ、Ⅵ级为主,60%以上的耕地面积已发生速效钾缺乏现象。土壤肥力动态监测结果表明,随着秸秆还田和平衡施肥技术的逐步推广,速效钾快速下降势头得到有效遏止,下降速度趋缓。
Through analyzing the available potassium content of topsoil in Rugao of Jiangsu Province from 1982 to 2002, the temporal and spatial changes of available soil K and the suitable amount of potash fertilizer were studied. The results show that in 20 years the available tillage soil available potassium content has changed significantly. In 2002, the content was only 50.51mg kg-1, which was 5.5mg kg-1 lower than that of 1982 and decreased by 9.80%. The available potassium content of cultivated land has been changed from Ⅳ and Ⅴ to 20% Ⅳ, Ⅴ and Ⅵ mainly from 20 years ago. More than 60% of the cultivated land has rapidly available potassium deficiency. Dynamic monitoring results of soil fertility showed that with the gradual popularization of straw returning and balanced fertilization techniques, the rapid decline of available potassium was effectively stopped and the rate of decline slowed down.