京郊小麦玉米轮作土壤有效硫的动态变化

北京近郊池栽小区试验发现 ,北京近郊小麦 玉米轮作体系土壤有效硫含量具有明显的季节变化 ,其中表层 (0～20cm )土壤的变化幅度最大 ,20～40cm土层次之 ,40～60cm土层最小 ,主要与大气、降水、灌水、植物吸收、淋溶等因素有关。小麦生育期内土壤剖面中有效硫含量呈从上层向下递减的趋势 ;玉米生育期表层土壤有效硫呈下降趋势 ,收获时成为三层中最低的一层 ,说明土壤有效硫在剖面中有明显的淋洗现象。北京远郊的小麦 玉米轮作体系中土壤表层有效硫变化趋势与近郊的相似 ,但变化幅度比近郊土壤小

DYNAMICS OF SOIL AVAILABLE S IN WHEAT MAIZE ROTATION OF BEIJING

Dynamics of available sulphur in soils of wheat maize rotation system was studied by microplot experiments in Beijing suburban. The results showed significant seasonal changes of soil available sulphur during wheat and maize growth periods. The degree of seasonal variety of available suphur in soil profile declined from surface to 60cm in depth. This was largely explained by dry and wet deposition, rainfall, irrigation, crop uptake, and leaching. Available sulphur concentration decreased downward from top layer in soil profile in wheat soil. And this kind of distribution pattern did not change during wheat growth. However, available S in 0～20cm layer decreased steadily during maize growing season and it changed from the highest in early season to the lowest of the three layers (0～20cm, 20～40cm, 40～60cm) in the end. It was suggested that a great amount of soil available S be leached during this period of time. The same trend was found in exurb fields except for lower content and smaller seasonal variation.