紫色土坡耕地耕层蓄水保土及耕性特征研究

The Study of Soil and Water Conservation and Tilth Characteristics of Cultivated-layer in Purple Soil Farmland

通过对重庆合川和云南楚雄紫色土坡耕地野外调查和土壤物理力学性质分析,对比研究了紫色土坡耕地耕层土壤的蓄水、稳定性及耕性特征。结果表明：（1）紫色土坡耕地耕层土壤入渗速率随土层深度而降低,0—20,20—40,40—60cm耕层土壤稳定入渗率分别为5.80-9.58,2.81-4.35,0.98-1.96 mm/min;而相应深度土壤最大有效库容分别介于49.93-66.26,46.04-59.05,37.42-43.55mm范围,0—20cm土壤兴利库容高产耕层大于低产耕层;（2）不同类型紫色土坡耕地耕层土壤稳定性差异明显,土壤团聚体结构均以〉5,5-3,3-0.5mm 3个粒级为主,且〉0.25 mm水稳性大团聚体含量随耕层深度显著降低;0—20cm耕层土壤稳定性指数依次为烟草高产耕层（2.96）〉玉米高产耕层（2.55）〉烟草低产耕层（2.45）〉玉米低产耕层（2.38）;20—40,40—60cm土层的玉米和烟草稳定性指数分别较0—20cm耕层降低0.44,0.64和0.66,0.71;（3）不同坡耕地耕层土壤抗剪强度和贯入阻力差异显著（p〈0.05）,土壤抗剪强度依次为玉米低产耕层（36kPa）〉玉米高产耕层（29kPa）〉烟草低产耕层（25kPa）〉烟草高产耕层（21kPa）,峰值出现在20—40cm;高产耕层的土壤贯入阻力在0.3-1.9 MPa,低产耕层则在0.5-2.5MPa变化,其峰值出现在40—50cm。紫色土坡耕地高产耕层具有稳定入渗率高、有效库容大、土壤持水性能较强、土壤结构稳定性高、表层土壤抗剪强度和贯入阻力较低的特征。

Taking the slope-farmland of purple soil in Hechuan,Chongqing and Chuxiong,Yunnan as samples,the study analyzed the soil water storage,soil stability and tilth characteristics based on field survey and lab tests.The results showed that：（1）Soil infiltration rate decreased with the increasing depth of cultivatedlayer of purple soil in slope-farmland,and the soil stable infiltration rate of the 0—20cm,20—40cm,40—60cm cultivated layer was 5.80 to 9.58mm/min,2.81 to 4.35mm/min,and 0.98 to 1.96mm/min,respectively.The maximum effective water storage capacity of soil was 49.93 to 66.26,46.04 to 59.05,and 37.42 to 43.55 mm at corresponding soil depth.（2）Soil stability of cultivated-layer was significantly different among purple soil farmlands.The〉5mm,5to 3mm,and 3to 0.5mm fractions were dominant soil aggregate structure,and the content of〉0.25 mm fraction of water stable aggregates decreased with increasing cultivated-layer depth significantly.Soil stability index of the 0—20cm cultivated-layer varied and followed the order of highyield tobacco cultivated-layer（2.96）〉high-yield maize cultivated-layer（2.55）〉low-yield tobacco cultivatedlayer（2.45）〉low-yield maize cultivated-layer（2.38）.Compared with that of the 0—20cm soil layer,the stability index of the 20—40cm and 40—60cm layer of maize and tobacco decreased by 0.44,0.64 and 0.66,0.71,respectively.（3）The soil shear strength and the penetration resistance of cultivated-layer on different slope-farmland was significantly different（p〈0.05）,and the soil shear strength was in the order of low-yield maize cultivated-layer（36kPa）〉high-yield maize cultivated-layer（29kPa）〉low-yield tobacco cultivatedlayer（25kPa）〉high-yield tobacco cultivated-layer（21kPa）,with the peaking value appearing in the 20—40cm layer.Soil penetration resistance of high-yield and low-yield cultivated-layer was 0.3to 1.9Mpa and 0.5to 2.5 MPa,with the peaking value appearing in the 40 to 50cm layer.The high-yield cultivated-layer of purple soil slope-farmland presented high stable infiltration rate,large storage capacity,strong soil water holding capacity,high soil structure stability,low soil anti-shear strength and penetration resistance.