江淮丘陵地区油-稻轮作条件下土壤硫库变化研究

Dynamics of soil sulphur pool under rape rice rotation in hilly regions between Yangtze and Huaihe rivers.

江淮丘陵地区下蜀系黄土母质发育的水稻土油稻轮作试验表明，油菜种植期间，耕层土壤硫主要来源于耕层以下土层的补给，其次是大气干湿沉降；该时期耕层土壤硫输出主要是油菜吸收，其次是淋失．油菜种植期间耕层土壤硫输入量小于输出，导致耕层土壤硫库下降８．７６ｋｇ·ｈｍ－２，２２％来自无机硫库的下降．水稻种植期间，耕层土壤硫输入主要来自灌溉水，其次是底土层的补给和大气干湿沉降；而硫输出主要是淋失，其次是水稻吸收．耕层土壤硫输入量大于输出，导致耕层土壤硫库增加１８．６９ｋｇ·ｈｍ－２，１８％来自无机硫库的增加．全年油稻轮作期间耕层土壤硫输入量大于输出，导致耕层土壤硫库增加９．９３ｋｇ·ｈｍ－２，１３％来自无机硫库的增加．

Field experiments of rape rice rotation cropping on paddy soils developed from loess parent material in hilly regions between Yangtze and Huaihe rivers indicated that during the period of rape growth, soil sulphur in plough layer mainly came from substratum, and then, from atmospheric deposition. The output of sulphur was mainly resulted from the absorption by rape, and next, from leaching by raining. The amount of sulphur input in plough layer was less than that of its output during the period of rape growth and the sulphur pool in plough layer was reduced by 8.76 kg·hm -2 ,22% of which was resulted from the decrease of inorganic sulphur pool. During rice growing, the sulphur input in plough layer mainly came from irrigation, and then, from the supply of substratum and atmospheric deposition. The output was resulted mainly from leaching, and next, from absorption by rice, The sulphur input in plough layer was more than its output, and the sulphur pool in top soil layer was increased by 18.69kg·hm -2 , 18% of which was resulted from the increase of inorganic sulphur pool. Therefore, the amount of sulphur imput in plough layer was more than that of its output during the whole rape rice rotation, and the sulphur pool in plough layer was increased by 9.93kg·hm -2 ,13% of which was from the increase of inorganic sulphur pool.