The Dynamics of Bulk Density and Porosity in Corn and Soybean Fields under Two Soil Water Index (SWI) Environments
Project Abstract
Soil Water Index (SWI) represents theoretical water stored in the soil at various depths. Low SWI means water limited and high SWI means saturated. The growth of crops is affected by soil moisture through the changes in soil physical properties. Restrictive bulk densities (BD) can have negative impacts on nitrogen loss rates, drainage rates, compaction, and root penetration, thus reducing crop growth and yield. The ideal BD range for crop growth in mineral soils is from 1.0 to 1.40 g/cm³. The purpose of this study was to determine the impact of SWI on BD and porosity under corn and soybeans. The research was conducted on silt loam soils in Harrison County, Indiana. Six samples were collected from each field at a depth of 7.5 cm with three replications each from the two environments (low versus high SWI). The results show that there was no significant difference in soil BD and porosity between the corn and soybeans fields as well as between high SWI and low SWI. The average soil BD for the saturated environment was 1.20 g/cm³, but 1.35 g/cm³ for the water limited environment. The average soil porosity for high SWI was 54.65%, but 49.18% for the low SWI. This study indicates that in general, soil moisture did not govern the level of soil compaction and aeration in the Indiana corn and soybean fields. However, soybeans show more sensitivity towards differences in SWI compared to corn.