贵州黄壤旱地有效镁的含量与镁肥盆栽效果分析

Quantity of Available Magnesium of Dry Cultivated Land and Effects of Applying Mg Fertilizer on the Crops in Yellow Earth Areas of Guizhou

通过对贵州中部不同母质发育的黄壤旱地进行野外调查，选择有代表性的２０个耕层土样进行室内分析，结果表明：在该区影响旱地有效镁数量的土壤因子以ｐＨ值最为重要，其次是速效磷含量。在第四纪红色粘土发育的黄泥土和黄色砂岩风化物发育的黄砂土上，对玉米和烤烟进行盆栽试验，结果表明：对土壤施钾后，植株氮、钾含量增大，但植株对镁的吸收明显减少；对土壤施镁后，植株氮、磷、镁含量变化不大，而植株钾的含量则出现下降趋势。因此，在强酸性缺磷的旱地或质地偏砂有效钾含量低的旱地上，对土壤进行补镁，具有较明显的增产效果；对施肥水平较高的高产旱地或长期连栽的烟地，适量施用镁肥，能改善养分之间的交互效应，促进植株生长。

The correlation coefficients of soil pH value, the contents of exchangeable Ca, exchangeable Al, and available P to the content of exchangeable Mg were obviously significant. The results of stepwise regression showed that soil pH value played the greatest part in the content of exchangeable Mg, the available P, and the second. Results on the nutrient status in the leaf of corn or flue cured tobacco demonstrated the Mg% in the leaf was obviously reduced under applying K fertilizer, and that the K% in the leaf had the trend of reduction with applying Mg fertilizer. Applying Mg fertilizer to the soils, with lower soil pH value and phosphorus deficiency or with magnesium deficiency, the growth of crops was promoted, and resulted to increase of yields.