稻作制与有机肥及地下水位对水稻土硫素状况的影响 Ⅱ.土壤无机硫的形态分级

Effects of Rice-Based Cropping System,Organic Manure and Ground Water Level on Sulfur Status in Rice Soil Ⅱ.The Fraction of Inorganic Sulfur

为了探明湖南省稻田土壤硫素状况及不同农业利用措施等对土壤硫素状况的影响,在测定全量硫和有效硫的基础上,采用李成保建议的连续提取法,测定了不同稻作制土壤各形态无机硫含量,并由差减法得出有机硫含量.结果表明,土壤中的硫以有机形态为主,约占土壤全硫的76.8%,无机态硫以吸附性硫为主,水溶性硫和盐酸可溶性硫含量相当.不同土壤层次间,A层土壤各形态硫含量最高,随着土壤剖面层次的加深,土壤各形态硫含量逐渐下降.不同稻作制间,耕层土壤有机硫含量以稻—稻—冬泡最高,稻—稻—冬绿次之,稻—稻—冬油最低;无机硫中吸附性硫含量从大到小依次为冬绿,冬油,冬泡.不同有机肥施用水平之间,耕层土壤有机硫含量以常量有机肥处理最高,高量有机肥处理居中,化肥处理最低,与土壤全硫含量变化规律一致.高地下水位有利于各土层土壤硫素的积累及土壤粘粒矿物对SO42-的吸附.

The sequential extraction approach advanced by Li Chengbao is applied to the study of the contents of three inorganic sulfur on the base of total S and available S. Organic S content is obtained by subtraction.The results indicate that organic S is 76.8% of total. In total inorganics,the contents of adsorbedS are the highest, followed by those of H2OS;While those of HClS are the lowest.Among 3 soil layers ,the contents of various fractions sulfur in plough layer are the highest. Among 3 ricebased cropping systems ,the organic S contents of plough layer in the treatment of ricericegreen manure in winter come the second, and those in the treatment of ricericerape in winter are the lowest; The contents of the adsorbed S in the treatment of green manure in winter are higher than that of rape and flooded follow in winter .Among 3 applications of organic manure,the organic S contents in the treatment of normal rate application of organic manure are higher than those in the treatment of high rate application of organic manure,while in the treatment of inorganic fertilizer the total S contents are the lowest,and the variation of the contents in organic S and total S are similar. Higher ground water level can increase the contents of total S and the adsorbed S in soil.