NH4+对K+在土壤肥际微域中迁移和转化的影响

NH4^＋和K^＋共施在农田施肥中是很普遍的现象,研究它们共施后二者在土壤中的交互作用对指导施肥具有重要意义。采用室内土柱实验研究了共施条件下NH4^＋对K^＋在红壤和潮土肥际微域中的迁移和形态转化的影响,供试肥料为NH4Cl和KCl。试验结果表明,与单施K^＋相比,共施NH4^＋没有改变肥料钾在红壤和潮土中的迁移距离,但提高了肥际微域中的水溶性钾含量;在靠近施肥点附近,NH4^＋的施用减少了土壤交换性钾含量,这种作用在潮土中的表现不如在红壤中明显;与单施KCl相比,共施NH4Cl明显降低了施肥点附近土壤微域内的非交换性钾含量。研究结果表明,共施NH4Cl减少了土壤晶格对钾离子的固定,增加了钾的淋溶风险。

EFFECT OF NH4+ ON MOVEMENT AND TRANSFORMATION OF K+ IN FERTILIZER MICROSITES IN SOILS

It is a common way to apply NH 4 and K together in farming.Effects of NH 4 on movement and transformation of K in fertilizer microsites in red soil and Fluvo-aquic soil were studied through an incubation experiment using soil columns.The fertilizers used in the experiment were NH4Cl and KCl.Compared with the treatment of application of K alone, the treatment of addition of NH 4 did not show any effect on diffusion distance of fertilizer K but did increase the concentration of water-extractable K in fertilizer microsites.In the soil close to the fertilizer placement site, the concentration of exchangeable K was decreased as a result of the addition of NH 4, which was not so apparent in Fluvo-aquic soil as in red soil.Besides, the addition of NH 4 significantly decreased the concentration of nonexchangeble K in fertilizer microsites, suggesting that the addition of NH 4 reduced K fixation in soil crystal lattices, thus increasing the risk of K leaching in the two soils.