作物幼苗根际土壤MB－S的初步研究

采用根际袋培养技术研究了大豆、玉米、油菜和水稻幼苗（６０ｄ）根际ＭＢ－Ｓ（ＭｉｃｒｏｂｉａｌＢｉｏｍａｓｓ－Ｓｕｌｆｕｒ）的根际效应及硫肥对根际ＭＢ－Ｓ的影响。结果表明：不施Ｓ，根际土壤ＭＢ－Ｓ在２１．６～２３．９ｍｇＳｋｇ－１（土）；油菜和水稻施Ｓ处理根际土壤ＭＢ－Ｓ为２２～２５ｍｇＳｋｇ－１（土）。作物根际土壤中ＭＢ－Ｓ含量比无作物处理提高了６５％～１３０％。非根际土壤ＭＢ－Ｓ在１２．５～１５．４ｍｇＳｋｇ－１（土），比无作物处理高７％～３３％。根际土壤ＭＢ－Ｓ是非根际土壤的１．７～２倍。水稻根际ＭＢ－Ｓ含量一般比旱作物高。与对照（无作物处理）相比根际ＭＢ－Ｓ增加百分数，水稻稍大于油菜，但明显低于大豆和玉米。硫肥施用对根际土壤ＭＢ－Ｓ的影响不大。作物根际土壤ＭＢ－Ｓ含量与其无机Ｓ呈直线正相关；与其有机硫呈直线负相关。在旱作物中根际土壤ＭＢ－Ｓ与土壤有机碳呈负相关，但在水稻中则相反。作物体含硫量与根际土壤ＭＢ－Ｓ含量呈负相关

The Soil MB-S around Rhizosphere of Crop Seedling

Microbial biomass sufur (MB-S) and other sulfur components in soils around rhizosphere and the adjacent area of soybean,corn,rapeseed and rice seedlings were investigated using nylon-bag method after crop harvest.Rhi.MB-S was in a range of 21 6-23 9mg/kg soil without sulfur application and 22 and 25mg/kg soil for rapeseed and rice,resp.with the application.Rhi.MB-S content increased by 65%-130% in soils with crops compared with that in soils without crop (CK).MB-S in Non-rhizosphere ranged from 12.5 to 15.4mg/kg soil,7%-33% higher than those of CK.MB-S of Rhi.soils was 1.7-2 times that of the non-rhi.soils,and highly significant correlation was found between the two MB-S.MB-S content was influenced by crop species,which was generally higher in rice than in upland crops.Comparing with the CK,the percentage increment of MB-S content in the soils with crops followed the similar trend.Application of sulfur didin't influence Rhi.MB-S content.The MB-S content of Rhi-soil corelated positively with the content of inorganic-S,but negatively with the content of organic-S.Soil organic cabon had negative effect on MB-S of upland crops but positive effect of paddy rice.Sulfur content of the crop plants correlated negatively with the MB-S content in Rhi-soils.