Optimization of Soil Structure Under Differing Climatic Regimes.

The complex aggregation patterns of soil particles—soil structure—result in a concomitant arrangement of pores within the soil media. The presence of this soil-particle organization has the effect of creating pores between aggregates (interpedal pores) that are larger than the pores within aggregates (matrix pores). These interpedal macropores can act as effective conduits for the transmission of water and thus have profound effects on soil water infiltration, redistribution, and drainage. In this study, we sought to discover how natural systems might theoretically optimize soil structure under varying climatic regimes. We developed a low-dimensional single-layer model to simulate the response of soil structural evolution to various frequencies and magnitudes of precipitation. We used a weighting coefficient in a dual-porosity model of water retention as the description of soil structure to distinguish pores resulting from aggregation from those in the matrix. The weighting coefficient was allowed to vary in order to optimize water flux through the soil column averaged over a yearly timescale. A stochastic precipitation model was used to simulate infiltrating water and evaporative demand at the top of the soil column. Simulation results from the model will be presented and implications for pedology will be discussed.