不同轮作制对农田生态系统中土壤硫攫取与归还途径的研究

研究了我国北方地区主要轮作制度下，土壤一植物生态系统中硫的主要输入(归还)与输出(攫取)途径．结果表明，在我国北方普遍推行的小麦-玉米轮作制中，作物收获物从土壤中攫取的硫素总量为每年26．4kg·hm^-2，由根系和植物其它残留物归还给土壤的硫素为每年6．8kg·hm^-2；在小麦．大豆轮作制中。作物收获物从土壤中攫取的硫素总量为每年24．4kg·hm^-2，对土壤的归还量为每年7．2kg·hm^-2；而在玉米-油菜轮作制中，收获物从土壤中攫取的硫量为每年45．4kg·hm^-2，归还给土壤的硫量为每年8．7kg·hm^-2；其它作物如棉花、高粱、花生、水稻种植一季通过收获物从土壤中带走的硫量分别为每年7．9、6．4、6．7和18．9kg·hm^-2。对土壤的归还量分别为每年2．6、1．8、4．3和5．6kg·hm^-2．通过对系统主要输入输出通量的估算，几种主要农田生态系统硫盈亏的状况计算结果说明，供试作物皆存在硫亏缺状况：小麦每年6kg·hm^-2、玉米8．5kg·hm^-2、油菜24kg·hm^-2、水稻7．1kg·hm^-2．

Pathways of soil sulfur input and output in agro-ecosystem under different cropping rotations

This paper mainly dealt with the pathways of sulfur (S) input and output in agro-ecosystems under general cropping rotations in northern China. The results indicated that in a typical corn-wheat rotation system, S output by the crop products was 26.4 kg.hm-2, and 6.8 kg.hm-2 of S was returned to the soil through root and plant residues. Under wheat-soybean rotation, 24.4 kg.hm-2 of S was removed from and 7.2 kg.hm-2 of S were returned to the soil. Under the rotation of corn with rape, up to 45.4 kg.hm2 was taken out from and only 8.7 kg.hm-2 returned to the soil, respectively. 7.9, 6.4, 6.7 and 18.9 kg.hm-2 of S output by products and 2.6, 1.8, 4.3 and 5.6 kg.hm-2 of S input by residues were obtained in cotton, sorghum, peanuts and paddy rice, respectively. Through estimation of S balance for these systems, 6, 8.5, 24 and 7.1 kg.hm-2.yr-1 of S was lost from soil by growing wheat, corn, rape and paddy rice, respectively.