水稻根际与非根际土壤硫素赋存形态转化及其迁移规律

在未污染及重金属污染水稻土上施用不同硫肥处理,通过池栽试验研究硫在水稻根际与非根际土壤中迁移规律及其赋存形态的影响.结果表明,在水稻生育期内,根际与非根际土壤溶液Eh、pH和pe+pH范围分别在93~283 mV和83~254 mV之间、7.5~8.4和7.7~8.4之间、9.1~13.2和9.1~12.5之间.根际土Eh总体上高于非根际土,根际土pH总体上低于非根际土.在根际土壤中,水溶性硫(占总无机硫的41%~81%,下同)吸附性硫(9%~34%)盐酸可溶性硫(8%~24%)盐酸挥发性硫(2%~8%).在分蘖期和抽穗扬花期,水溶性硫和吸附性硫的质量分数,施用石膏处理的显著性高于单质硫处理的;对未污染水稻土,其质量分数显著性高于污染水稻土的.在非根际土壤,水溶性硫(40%~69%)盐酸可溶性硫(18%~41%)盐酸挥发性硫(6%~16%)吸附性硫(0.7%~7.5%).根际土与非根际土壤的无机硫质量分数分别为223~738mg·kg~(-1)和68~128 mg·kg~(-1),土壤有机硫质量分数分别为574~1 647 mg·kg~(-1)和108~391 mg·kg~(-1),总硫的质量分数分别为825~2 287 mg·kg~(-1)和200~477 mg·kg~(-1).水稻根际土中,无机硫和有机硫分别占总硫20%~40%和60%~80%;非根际土为18%~46%和54%~82%.水稻根际土在总硫、有机硫、水溶性硫、吸附性硫和盐酸可溶性硫的质量分数分别是非根际土壤的3~11倍、3~5倍、5~7倍,12~20倍、2~3倍,而盐酸挥发性硫的质量分数低于非根际土.

Transformation and Migration of Sulfur Speciation in the Rhizosphere and Bulk Soil of Paddy Soil

A pool culture experiment was carried out to investigate the influence of different forms of sulfur fertilizers (sulfur and gypsum) on the transformation and migration of sulfur speciation in the rhizosphere and bulk soil of unpolluted and polluted paddy soils.The results showed that the redox potential (Eh) was about 93-283 mV and 83-254 mV, respectively, the soil solution pH was 7.5-8.4 and 7.7-8.4, respectively, and pe+pH was 9.1-13.2 and 9.1-12.5, respectively, in the bulk and bulk soil.Solution Eh values in Rhizosphere soil were generally higher than those in bulk soil, and solution pH in the former was generally lower than that in the latter.The different forms of inorganic sulfur followed the order of water-soluble sulfur (41%-81% of total inorganic sulfur, similarly hereinafter)>>sulfur adsorption (9%-34%)>hydrochloric acid soluble sulfur (8%-24%)>hydrochloric acid volatile sulfide (2%-8%) in the rhizosphere.In tillering and earing flowering,the concentrations of water-soluble and absorbed sulfur by application of gypsum were significantly higher than those using elemental sulfur.And its content in unpolluted paddy soil was significantly higher than that in polluted paddy soil. In the bulk soil,the forms of inorganic sulfur followed the order of water-soluble sulfur (40%-69%)>>hydrochloric acid soluble sulfur (18%-41%)>hydrochloric acid volatile sulfide (6%-16%)>adsorbed sulfur (0.7%-7.5%).The mass fractions of inorganic sulfur, organic sulphur and the total sulfur in the rhizosphere soil were in the range of 223-738 mg·kg^-1, 574-1647 mg·kg^-1 and 825-2287 mg·kg^-1,respectively,and the corresponding fractions were in the range of 68-128 mg·kg^-1, 108-391 mg·kg^-1 and 200-477 mg·kg^-1 in the bulk soil,respectively.Inorganic sulfur and organic sulfur of total sulfur in the rhizosphere were 20%-40% and 60%-80%, respectively, and those in the bulk were 18%-46% and 54%-82%, respectively.Total sulfur. organic sulfur and water-soluble sulfur and adsorbed sulfur and hydrochloric acid soluble sulfur in the rhizosphere were 3-11 times, 3-5 times, 5-7 times, 12-20 times, and 2-3 times of those in the bulk soil, respectively, whereas the hydrochloric acid volatile sulfur in the rhizosphere was lower than that in the bulk soil.