Physical Quality Indicators and Mechanical Behavior of Agricultural Soils of Argentina

Mollisols of Santa Fe have different tilth and load support capacity. Despite the importance of these attributes to achieve a sustainable crop production, few information is available. The objectives of this study are i) to assess soil physical indicators related to plant growth and to soil mechanical behavior; and ii) to establish relationships to estimate the impact of soil loading on the soil quality to plant growth. The study was carried out on Argiudolls and Hapludolls of Santa Fe. Soil samples were collected to determine texture, organic matter content, bulk density, water retention curve, soil resistance to penetration, least limiting water range, critical bulk density for plant growth, compression index, pre-consolidation pressure and soil compressibility. Water retention curve and soil resistance to penetration were linearly and significantly related to clay and organic matter (R2 = 0.91 and R2 = 0.84). The pedotransfer functions of water retention curve and soil resistance to penetration allowed the estimation of the least limiting water range and critical bulk density for plant growth. A significant nonlinear relationship was found between critical bulk density for plant growth and clay content (R2 = 0.98). Compression index was significantly related to bulk density, water content, organic matter and clay plus silt content (R2 = 0.77). Pre-consolidation pressure was significantly related to organic matter, clay and water content (R2 = 0.77). Soil compressibility was significantly related to initial soil bulk density, clay and water content. A nonlinear and significantly pedotransfer function (R2 = 0.88) was developed to predict the maximum acceptable pressure to be applied during tillage operations by introducing critical bulk density for plant growth in the compression model. The developed pedotransfer function provides a useful tool to link the mechanical behavior and tilth of the soils studied.

圣达菲地区的暗沃土（Mollisols）具有各异的耕性与荷载承载能力。尽管这些属性对实现作物可持续生产至关重要，但目前相关公开数据仍较为匮乏。本研究的核心目标为：其一，评估与植物生长及土壤力学行为相关的土壤物理指标；其二，建立关联关系以估算土壤荷载对植物生长相关土壤质量的影响。本研究在圣达菲地区的黏化暗色湿润淋溶土（Argiudolls）与普通暗色湿润淋溶土（Hapludolls）样地开展。采集土壤样品以测定其质地、有机质含量、容重、持水曲线、土壤穿透阻力、最小限制水分范围、植物生长临界容重、压缩指数、前期固结压力及土壤压缩性。持水曲线与土壤穿透阻力分别与黏粒、有机质含量呈显著线性相关，决定系数R²分别为0.91与0.84。基于持水曲线与土壤穿透阻力的土壤传递函数（pedotransfer functions），可估算植物生长所需的最小限制水分范围与临界容重。研究发现，植物生长临界容重与黏粒含量间存在显著非线性相关关系（R²=0.98）。压缩指数与容重、含水量、有机质含量及黏粉粒总含量呈显著相关（R²=0.77）。前期固结压力与有机质、黏粒及含水量呈显著相关（R²=0.77）。土壤压缩性则与初始土壤容重、黏粒及含水量呈显著相关。本研究构建了一个决定系数为0.88的显著非线性土壤传递函数，通过将植物生长临界容重引入压缩模型，可预测耕作作业中可施加的最大允许荷载。所构建的土壤传递函数可为关联研究区域土壤的力学特性与耕性提供实用工具。