改良剂对粉砂质涂地土壤水稳定性团聚体形成和养分供应能力的影响

比较了国内外常用的3种结构改良剂（聚丙烯酰胺、β-环糊精和腐殖酸）对促进粉砂质涂地土壤水稳定性团聚体形成的效果，分析了应用结构改良剂对土壤养分供应能力的影响。结果表明，施用3种结构改良剂均可在一定程度上促进水稳定性团聚体的形成，水稳定性团聚体的数量随改良剂用量增加而增加。3种改良剂对水稳定性团聚体的改良效果由高至低顺次为：聚丙烯酰胺>β-环糊精>腐殖酸。聚丙烯酰胺和β-环糊精的适用量以0.20%为宜。施用腐殖酸对土壤氮、磷、钾养分供应影响不明显；但聚丙烯酰胺和β-环糊精可明显改变土壤养分的供应状况。对于施肥后再施用改良剂的土壤，土壤释放养分的能力有一定的减弱；而对于施改良剂后再施肥料，土壤对化肥中养分的吸持能力减弱，供肥能力增加。

Effects of Amendments on Formation of Water-Stable Aggregates and Supply Capacity of Nutrients in Silty Sand Coastal Soil

A pot incubation experiment was conducted to compare the effects of three structure modifiers (polyacrylamide, β-cyclodextrin, and humic acid), used widely at home and abroad, on formation of waterstable aggregates and supply capacity of nutrients in a silty coastal soil. The result showed that application of each of three structure modifiers could improve the formation of water-stable aggregates in the soil, and the amounts of >0.25 mm water-stable aggregates in the soil increased with increasing the rates of the modifiers. The improved effects decreased in the order of polyacrylamide > β-cyclodextrin > humic acid. The optimal dosage of polyacrylamide and β-cyclodextrin for modifying soil structure was about 0.20%. Application of humic acid had no significant effect on supply capacity of nutrients in the soil. However, application of polyacrylamide and β-cyclodextrin could change supply capacity of nutrients in the soil. The soil, added with modifiers after application of chemical fertilizers, had weaker supply capacity of nutrients as compared with control without application of any amendments. While the soil, added with chemical fertilizers after application of modifiers, had stronger supply capacity of nutrients as compared with control.