秸秆-膨润土-PAM改良材料对沙质土壤磷素吸附解吸的影响

Effect of Straw-Bentonite-PAM Improved Material on Phosphorus Adsorption-Desorption of Sandy Soil

为了提高沙质土壤保肥能力,降低磷素流失风险,以重庆市分布面积较大的冷沙黄泥为研究对象,将生物预处理后的作物秸秆与膨润土、聚丙烯酰胺(PAM)结合,配制成秸秆改良材料,探究了改良材料种类、添加量及配比等因素对沙质土壤磷吸附解吸的影响。结果表明:采用Langmuir方程能很好地反映沙质土壤对磷的吸附。施加秸秆改良材料可以显著提高沙质土壤对磷的吸附率,降低解吸率;显著增加吸附常数(K)和最大缓冲容量(MBC),减小磷的最大吸附量(Xm)。油菜秆改良材料的改良效果比小麦秆更好。改良材料施用量越大或PAM水平越高,改良效果越明显。培养90天后,添加油菜改良材料(添加量为10g/kg,配方中PAM水平为3%)对沙质土壤的改良效果最明显。试验为秸秆应用于改良沙质土壤提供了科学依据。

In order to improve the fertilizer retention and reduce the risk of phosphorus leaching of sandy soils that distributes widely in Chongqing City, improved materials confected by biological pretreatment straw, bentonite and PAM were used, the influences on phosphorus adsorption and desorption of the sandy soil result from different materials, dose and ratio were studied. The results showed that： Langmuir equation could reflect the adsorption reaction well. Improved materials could significantly increase the phosphorus adsorption rate of sandy soil, while reduce the desorption rate. The maximum adsorption capacity （Xm） was reduced obviously, while the adsorption constant （K） and maximum buffering capacity of phosphorus （MBC） of the sandy soil was significantly increased. The improvement materials made of rape stalk was better than that of wheat straw. WithAfter 90 days in culture, the improvement materials of rape stalk （dose of 10 g/kg, PAM level of 3%） showed the most obvious improvement effect to the sandy soil. This research provided theoretical basis of applying modified straw materials into sandy soil.