酸性紫色土长期定位施钾效应及对土壤肥力的影响

CROP RESPONSES TO CHEMICAL K AND FARM MANURE K FERTILIZERS IN LONG-TERM FIELD TRIALS AND THEIR EFFECTS ON FERTILITY OF ACIDIC PURPLE SOIL

通过对酸性紫色土１２年的稻、麦轮作，有机、无机定位施钾的研究证明：ＮＰＫ或农ＮＰＫ配施的产量高，效果好；施钾时间愈长，增产愈显著；施钾对下一季作物有后效。经测定，连续施钾的土壤容重降低，孔隙率提高，有机质和氮、磷含量增加。通过对稻、麦、油主要生育期的植株分析得出：三种作物适宜的钾氮比分别为０．６、０．５、０．４，可作为预测缺钾和诊断施钾的依据。

A long term field trial was conducted to test effects of chemical K and/or checmical K plus farm manure on crops grown on an acid purple soil under rice-wheat (rapeseed) rotations. The results from the past 12 years showed that NPK treatment or farm manure plus NPK treatment had the highest growth and grain yield. The yield increases corresponded to an increase in duration of K application. In any case, K showed a residual effect on the successive crops. On the plots successively receiving K fertilizers, it resulted in a reduction in bulk density and an increase in porosity, content of organic matter, N and P as well. The results suggested that the appropriate K: N ratios for rice, wheat and rapeseed crops in their growing period were 0. 6, 0. 5 and 0. 4, respectively. The ratio could be used as an indicator in evaluation of K status in the plant and as a reference for K fertilization during the growing seasons.