京郊典型农田生态系统中硫的源汇关系研究

研究了京郊小麦-玉米轮作典型农田生态系统中S的源汇关系,分析了该区农田生态系统主要特征、经济基础以及各项农事活动对生态系统中S来源与归宿的影响,指出该区农田生态系统中S的源和汇在不同时期依据不同对象发生交替性动态变化,根据系统中能量流、生态流与元素流的矢量与转化过程初步确定系统中S的输入与输出途径、S的补偿效应及其盈亏平衡,1个轮作期中玉米和小麦收获物对S的输出量分别为14.66kg/hm~2和11.8kg/hm~2,通过根系和秸秆还田对土壤S的归还量分别为2.78kg/hm~2和9.73kg/hm~2,加上其他途径对土壤系统S输出/输入的估算,年S输出总量为46.1kg/hm~2,年输入总量为37.2kg/hm~2,年土壤系统S亏缺量为8.9kg/hm~2,故应定期补施一定量的S肥。

Studies on the relationship between source and pool of sulfur in typical agro-ecosystems of Beijing suburb

Studies on relationship of sulfur (S) source and pool in typical agro-ecosystems of Beijing suburb are carried out.The paper mainly deals with the characteristics of the system,effect of economy and farming style on S input and output.The results show that the source and pool of S in some subsystems can be changed at different periods.Based on the direction and rates of S flux into and from the system,the pathways,complementary effects,profit and loss are determined quantitatively.For example,after a complete rotation,the outputs of S by corn and wheat are 14.66kg/hm2 and 11.8kg/hm2,the inputs are 2.78kg/hm2 and 9.73kg/hm2 through roots and residues returned to soil,respectively.Taking account of all the pathways,46.1kg/hm2 S is lost from and 37.2kg/hm2 annually can be returned to the soil.Therefore,we can suggest that 8.9kg/hm2 S per year should be replaced by S containing fertilizers to compensate S loss from the soil.