黄土高原长期种植苜蓿对土壤硫、钙、镁的影响

Effect of Long-term Alfalfa Succession on Soil Sulfur,Calcium,and Magnesium in the Loess Plateau

以22年定位试验为基础,研究黄土高原长期种植紫花苜蓿(Medicago sativaL.)情况下土壤硫、钙、镁组分的变化。结果表明:长期施P使苜蓿连作耕层土壤总硫、有效硫、水溶性硫、吸附性硫、HCl可溶性硫、总无机硫和有机硫含量分别增加9.41%、62.41%、47.51%、30.07%、2.25%、5.38%和17.54%;长期施NPM使苜蓿连作耕层土壤总硫、有效硫、水溶性硫、吸附性硫、HCl可溶性硫、总无机硫和有机硫含量分别增加20.89%、98.31%、68.44%、57.34%、8.07%、12.54%和37.69%。长期施P使苜蓿连作耕层土壤全钙、有效钙、水溶态钙、交换态钙和酸溶态钙含量增加分别增加4.64%、4.27%、11.66%、4.05%和8.59%,但残余态钙含量降低2.21%;长期施NPM使苜蓿连作耕层土壤全钙、有效钙、水溶态钙、交换态钙和酸溶态钙含量增加分别增加8.69%、8.30%、51.59%、6.73%和27.77%,但残余态钙含量降低26.23%。长期施NPM使苜蓿连作耕层土壤全镁、有效镁、水溶态镁、交换态镁、酸溶态镁和残余态镁含量分别增加7.38%、61.98%、63.16%、61.85%、5.81%和8.97%。此外,有效硫在土壤剖面上出现双累积峰,有向深层土壤迁移的特征;有效钙、有效镁在土壤剖面上存在淋溶累积现象。此研究结果可为苜蓿种植和管理提供依据。

Sulfur, calcium, and magnesium are essential elements in plant and play very important functions in physiology and plant nutrition. Based on the long-time stationary experiment, the changes of soil sulfur, calcium and magnesium were studied under a condition of 22-year alfalfa succession in Loess Plateau. The results show that the contents of total sulfur, available sulfur, water soluble sulfur, adsorbent sulfur, HCl soluble sulfur, total inorganic sulfur, and organ sulfur in tilth soils, after long-time P-fertilizer application, increased by 9.41%, 62.41%, 47.51%, 30.07%, 2.25%, 5.38%, and 17.54%, respectively. The contents of total sulfur, available sulfur, water soluble sulfur, adsorbed sulfur, HC1 soluble sulfur, total inorganic sulfur, and organic sulfur in tilth soils, after long-time NPM-fertilizer application, increased by 20.89%, 98.31%, 68.44%, 57.34%, 8.07%, 12.54%, and 37.69%, respectively. The contents of total calcium, available calcium, water soluble calcium, exchangeable calcium, and HCl soluble calcium in tilth soils, after long-time P-fertilizer application, increased by 4. 64%, 4. 27%, 11. 66%, 4.05 %, and 8.59 %, respectively, but the content of residual calcium decreased by 2.21 %. The contents of total calcium, available calcium, water soluble calcium, exchangeable calcium, and HCl soluble calcium in tilth soils, after long-time NPM-fertilizer application, increased by 8.69%, 8.30%, 51.59%, 6.73%, and 27. 77%, respectively, but the content of residual calcium decreased by 26.23%. The contents of total magnesium, available magnesium, water soluble magnesium, exchangeable magnesium, HCl soluble magnesium, and residual magnesium in tilth soils, after long-time NPM-fertilizer application, increased by 7.38%, 61.98%, 63.16%, 61.85%, 5.81%, and 8.97%, respectively. Two peaks of available sulfur in soil profiles were detected with a transportation trend of available sulfur to deep soil layers. Additionally, the eluviation and accumulation of available calcium and magnesium occurred in soil profiles.