重庆江津区柑橘地土壤大孔隙特征

以重庆市江津区不同柑橘地为研究对象,采用土壤坡面染色法标记大孔隙、利用土壤水分穿透曲线方法及Poiseulle方程分析其土壤大孔隙特征。结果表明:染色区较非染色区有更大的稳定出流速率,大孔隙使染色区的水分渗透速率较非染色区提高了1.48倍以上,随着土层深度增加,其提高程度有增大的趋势。虽然染色区较非染色区更利于水分或溶液传导,但相比非染色区,染色区水分渗透曲线的波动更大。柑橘地大孔隙孔径范围在0.3～1.7mm之间,0.3～0.7mm孔径数量虽然为104数量级,但对染色溶液优先迁移的作用较弱;实际影响染色溶液迁移的为半径大于0.7mm的土壤大孔隙;20年林龄柑橘地10-20cm土层有效大孔隙数量高于10年林龄柑橘地。半径大于1.0mm的大孔隙在水分输入初期起到迅速排导水分的作用。柑橘地土壤大孔隙率在1.5%～19.5%之间,与稳定出流速率呈极显著正相关关系,决定了稳定出流速率71.9%的变异;半径大于0.7mm的大孔隙数量与稳定出流速率呈极显著正相关关系,决定了稳定出流速率90.9%的变异。

Soil Macropore Characterisics Under Citrus Land in Jiangjin City,Chongqing

Soil macropore characteristics under different citrus land in Jiangjin city of Chongqing was analyzed by using brilliant blue dye method,water breakthrough curve and Poiseulle equation.The results showed that the steady effluent rate of the dye-stained area was more than 1.48 times higher than the dye-unstained area and the ratio become higher with soil depth.Water breakthrough curves in the dye-stained area had a bigger fluctuation than that in the dye-unstained area.The radii of soil macropores were from 0.3 mm to 1.7 mm.Radii(0.3~0.7 mm) had little effect on preferential flow despite the 104 magnitude.The macropores with radii larger than 0.7 mm was the main factor affecting the preferential flow.At the 10-20 cm soil layer,the number of soil macropores under 20-year-old citrus land was larger than that under 10-year-old citrus land.The macropores with radii larger than 1.0 mm was the main preferential flow path in the initial stage of water input.The macroporosity was positively(P<0.01) related to the steady effluent rate in the range from 1.5% to 19.5% which contributed 71.9% to the variance of steady effluent rate.The macropores with radii larger than 0.7 mm was positively(P<0.01) related to the steady effluent rate which contributed 90.9% to the variance of steady effluent rate.