稻田土壤合理施用石灰的研究

LIMING OF PADDY SOILS

稻田水旱轮作交替过程中,由于土壤因淹水一排水而造成的还原物质的变化,土壤pH也随之发生变化,当生产中用石灰来调节土壤pH以满足作物的适生条件时,必须充分考虑这些特点。稻田土壤pH值在5.5以下,或稻草直接施入酸性稻田土壤时,可适当施用石灰,施用量视土壤性质和缓冲性能而定,一般以亩施30—50公斤作基肥为宜。土壤pH在5.6以上,淹水后还会上升,施低量石灰无明显效益,施高量石灰会破坏土壤肥力,减少水稻吸收N、P、K元素数量,权衡利弊,可不必施用石灰。

There are a fluctuation of Eh reducible substance and pH in paddy soils. Generally, Eh declined, pH risen and reducible substance increased after irrigation, and contrary when soils drained. But the fluctuation are different between soils, liming must be taken at a suitablep pH range. Liming can handled when soils pH below 5.5, 30-50 kg per mu dependent on the buffering of soils. Liming were not necessary to soils pH higher than 5.6 for no good effects to rice growth, Heavy liming were negligible in our experiments for disturbing the absorption of nitrogen phosphorus and potassium nutrients, and associate with soil fertility degradation.