The objective of the present study was to describe the relationships between soil physical properties and to identify variables that determine the pore system and hydrological functions which are specifically important in drought prone semiarid marginal croplands. We compared Mollisols under natural vegetation (NV) with their agriculture (AG) pairs in the central Argentinean Dry Pampas to obtain the range of values for variables that characterize the soil pore system. These were total carbon (OC), bulk density (BD), structural instability index (SII), volumetric weight of aggregates (VAW), total porosity (TP), macropores (Ma), saturated hydraulic conductivity (K), infiltration rate (IR), Dexter's S index (S), and least limiting water range (LLWR). To a depth of more than 23 cm, TP and Ma were considerably lower (~ 35% and 50% less, respectively) in AG versus NV. The changes in porosity and pore size resulted in 74% smaller IR and 65% lower K. The S index had mean values of 0.16 and 0.14 for the upper and middle layer respectively in NV; while for AG, these values were significantly lower (0.09 and 0.10, respectively). The LLWR was also lower in AG (21 and 59% less in the upper and middle layer, respectively), due to high soil resistance even at non-limiting BDs (1.17 and 1.32 g cm⁻³ for AG2 and AG1, respectively). Soil OC was positively correlated with TP, Ma, and S, and negatively correlated with BD and SII. Multiple regression models for S included SII, TP, and clay contents, while for LLWR the variables were OC, TP, and clay plus silt. Thus, these complex soil quality indices can be predicted by using simpler physical parameters, but texture and organic matter also have a strong effect on them. Moreover, our results contribute to a better understanding of the role of texture and organic matter in controlling soil physical quality and for maintaining soil-based ecosystem services.

本研究的目的是描述土壤物理性质之间的关系，并确定确定孔隙系统和水文功能的变量，这些变量在易干旱的半干旱边缘农田中特别重要。我们将阿根廷中部干草原的自然植被（NV）下的Mollisols与农业（AG）对进行了比较，以获得表征土壤孔隙系统的变量的取值范围。这些是总碳（OC），堆密度（BD），结构不稳定性指数（SII），集料的体积重量（VAW），总孔隙率（TP），大孔（Ma），饱和导水率（K），渗透率（ IR），德克斯特的S指数（S）和最小极限水域（LLWR）。深度超过23厘米时，TP和Ma大大降低（分别降低了约35％和50％，分别在AG与NV中进行。孔隙率和孔径的变化导致IR降低74％，K降低65％。N中上层和中层的S指数平均值分别为0.16和0.14。而对于AG，这些值要低得多（分别为0.09和0.10）。由于即使在非限制性BDs（1.17和1.32 g·cm）下仍具有较高的耐土壤性，AG的LLWR也较低（上层和中层分别减少21％和59％）。AG2和AG1分别为^-3）。土壤OC与TP，Ma和S呈正相关，与BD和SII呈负相关。S的多元回归模型包括SII，TP和黏土含量，而LLWR的变量为OC，TP和黏土加淤泥。因此，可以通过使用更简单的物理参数来预测这些复杂的土壤质量指标，但是质地和有机质也对其具有很强的影响。此外，我们的结果有助于更好地理解质地和有机物在控制土壤物理质量和维持基于土壤的生态系统服务中的作用。