A Comparison of Two Models to Evaluate Soil Compaction Effects On Corn Root Growth.

Several complex interactions among soil physical properties influence root growth of common crops. Models are used to combine limitations of temperature, aeration, water availability and soil strength to determine the zonal suitability for root growth. Two models are compared in this study, the Jones model used in several crop growth simulation models and the Least Limiting Water Range (LLWR) model. Root growth was measured at the V6, V12, and R1 growth stages for irrigated corn in northeastern Colorado. Soil water holding capacity and soil penetrometer resistance were measured for the Weld loam used in the study. Season-long water contents were measured and the suitability for root growth was calculated for each model. The root growth rate was determined at each growth stage and was compared with the relative growth rate predicted from the Jones and LLWR models. The LLWR model better predicted the effects of variable soil conditions on root growth than the Jones model. However, more site-specific soil information is required for the LLWR model such as measurements of the water content at field capacity and the water content – bulk density – soil strength relationships based on soil type and specific management.