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坡耕地是一个区域最易发生水土流失的土地利用类型,其严重的水土流失、面源污染和耕层退化现象直接威胁着坡耕地持续利用以及当地粮食安全、生态安全;耕层土壤质量对自然因素和人为耕作活动的影响较为敏感。本文以南方三个地点紫色土坡耕地耕层土壤质量为研究对象,从土壤属性角度,对比分析了重庆合川、江西兴国、云南楚雄不同耕层垂直深度土壤养分特征、土壤物理性质、土壤水库特征、耕作性能差异性及其形成原因。结果表明:(1)坡耕地耕层土壤有机质表现为云南楚雄(28.80 g/kg)>江西兴国(9.03 g/kg)>重庆合川(8.80 g/kg);除全钾含量外,土壤全量养分和速效养分的含量表现为云南楚雄>江西兴国>重庆合川;坡耕地耕层速效养分垂直分布变化规律基本一致,主要表现为土壤速效养分主要在0—20 cm土层富集,而20—40 cm和40—60 cm土层无显著差异。(2)不同地点紫色土坡耕地耕层土壤物理性质差异明显,以重庆合川坡耕地土壤物理质量最差,表现为土壤砂粒含量>60%、土壤容重最大(1.43 g/cm3)、土壤总孔隙度(45.97%)和毛管孔隙度(34.36%)最小;从坡耕地耕层土壤物理性质垂直变化特征看,耕作层(0—20 cm)优于心土层(20—40 cm)和底土层(40—60 cm)。(3)紫色土坡耕地耕层土壤初始入渗率以江西兴国坡耕地耕层最大(0.32 mm/min),而以重庆合川坡耕地耕层最小(0.19 mm/min);土壤稳定入渗率和平均入渗率均表现为云南楚雄>重庆合川>江西兴国;坡耕地耕层土壤最大有效库容以云南楚雄最好(873.311t/hm2),说明云南楚雄紫色土坡耕地耕层土壤具有较好的抵御季节性干旱能力;不同地点坡耕地耕层土壤总库容、死库容、兴利库容、滞洪库容、最大有效库容在垂直方向变化表现为耕作层(0—20 cm)大于心土层(20—40 cm)和底土层(40—60 cm)。(4)不同地点紫色土坡耕地耕层土壤抗剪强度和贯入阻力均呈现出相同变化规律,土壤抗剪强度表现为重庆合川(15.39 kg/cm2)>云南楚雄(14.74 kg/cm2)>江西兴国(10.66 kg/cm2),而土壤贯入阻力值为重庆合川(424.83 kPa)>云南楚雄(252.50 kPa)>江西兴国(188.87 kPa),这种土壤力学性能的变化说明重庆合川紫色土坡耕地耕层土壤具有较好抵抗剪切破坏的能力和较大耕作阻力。上述研究结果可为不同地点紫色土坡耕地耕层土壤质量诊断、坡耕地合理耕层评价提供理论依据和数据支持。
Slope cultivated land is the most land-use type of soil erosion in a region. Its severe soil erosion, non-point source pollution and degradation of farmland directly threaten the sustainable utilization of slope farmland and local food security and ecological security; Factors and human tillage activities more sensitive. In this paper, the soil quality of topsoil in purple soil was studied in three sites of southern China. From the perspective of soil properties, the vertical depth of soil nutrients, soil physical properties and soil reservoir characteristics of Hechuan of Chongqing, Jiangxi Province and Chuxiong of Yunnan Province were compared and analyzed. Differences of Tillage Performance and Causes of Its Formation. The results showed as follows: (1) The contents of organic matter in topsoil of slope farmland were as follows: Chuxiong of Yunnan (28.80 g / kg)> Xingguo of Jiangxi (9.03 g / kg)> Hechuan of Chongqing> 8.80 g / kg; The content of available nutrients in the topsoil showed the same trend as that in Chuxiong of Yunnan> Xingguo of Jiangxi> Hechuan of Chongqing. The vertical distribution of available nutrients in the topsoil was the same with that in the 0-20 cm soil layer, while that of 20-40 cm and 40-60 cm soil layer no significant difference. (2) The physical properties of topsoil in purple soil sloping farmland differed significantly in different locations. The physical quality of the soil in Hechuan sloping farmland in Chongqing was the worst. The soil physical properties were the worst, with the content of sandy soil> 60%, the maximum soil bulk density (1.43 g / cm3) (45.97%) and capillary porosity (34.36%) were the lowest. According to the vertical variation of physical properties of topsoil, the topsoil (0-20 cm) was superior to the top soil layer (20-40 cm) (40-60 cm). (3) The initial infiltration rate of topsoil in purple slope farmland was the highest (0.32 mm / min) in Xingguo slope farmland in Jiangxi Province and the lowest (0.19 mm / min) in farmland in Hechuan slope of Chongqing. The stable infiltration rate And the average infiltration rate showed that Chuxiong of Yunnan> Hechuan of Chongqing> Xingguo of Jiangxi; the maximum effective storage capacity of topsoil in slope farmland was the best in Chuxiong of Yunnan (873.311t / hm2) (0-20 cm) was greater than that of the soil layer (20-20 cm) in the top layer of the plow layer. The total available storage capacity, dead storage capacity, -40 cm) and subsoil (40-60 cm). (4) The shear strength and penetration resistance of topsoil in purple soil slope showed the same variation trend in different locations, and the shear strength of soil in Chongqing was the highest in Hechuan of Chongqing (15.39 kg / cm2)> Chuxiong of Yunnan (14.74 kg / cm2)> Jiangxi Xingguo (10.66 kg / cm2), while the soil penetration resistance values of Chongqing Hechuan (424.83 kPa)> Yunnan Chuxiong (252.50 kPa)> Jiangxi Xingguo (188.87 kPa) Soil plowed cultivated land has better resistance to shear failure and greater farming resistance. The above results can provide theoretical basis and data support for the diagnosis of topsoil quality and the evaluation of rational tillering on sloping farmlands in different locations.