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镇宁扬丘陵地区低产土壤(板浆白土、小粉土、青泥条等)占全区耕地的20%以上,加上旱地的死黄泥、死红土等低产士则超过30%.其中尤以占低产土壤面积比重最大的板浆白土生产水平最低.1961～1966年在该地区竹箦农场进行的大量试验表明,所有低产土上氮、磷肥肥效都极显著,而钾肥的效果不明显.1979年在该场同样类型土壤上再度进行试验.由于十多年的增肥改土,土壤肥力已有很大改善,作物单产提高二倍以上.试验结果与13年前完全不同.磷肥效果明显下降,甚至无效,而钾肥的效果几与六十年代的磷肥相似.为了揭示土壤三要素养分平衡的动
The low-yielding soil (slab clay, small silt, green clay, etc.) in the Ningyangyang hilly area accounts for more than 20% of the total cultivated land in the region, plus more than 30% of low-yielding dead yellow clay and dead clay in the dry land. Accounting for the lowest proportion of slashy clay with the lowest proportion of soil area in the low yielding area.A large number of experiments conducted in Zhunan farm in the area from 1961 to 1966 showed that the effect of nitrogen and phosphate fertilizers on low yielding soil was extremely significant and the effect of potassium fertilizer was not obvious. Year in the field of the same type of soil again test.Because of more than ten years of fertilizer to soil, soil fertility has been greatly improved, crop yields more than doubled.The results of the experiment and 13 years ago completely different.The effect of phosphate fertilizer decreased significantly , And even invalid, and the effect of potash fertilizer and the sixties similar to phosphate fertilizer.In order to reveal the three elements of soil nutrient balance move