Advances and challenges in predicting agricultural management effects on soil hydraulic properties

Agricultural management practices can significantly affect soil hydraulic properties and processes in space and time. These responses are coupled with the processes of infiltration, runoff, erosion, chemical movement, and crop growth. It is essential to quantity and predict management effects on soil properties in order to model their consequent effects on production and the environment. We present work done thus far on this topic area along with the challenges that lie ahead. The effects of tillage and reconsolidation, wheel-track soil compaction, crop residue management, macropore development and management interactions with natural sources of variability, such as topography, are addressed. Whether explicitly or implicitly, the available field studies include interactions between treatments, such as tillage, crop rotation and residue management. Controlled equipment traffic has been shown to have significant effects on soil compaction and related hydraulic properties in some soils and climates, but in others, landscape and temporal variability overwhelm any effects of wheel tracks. New research results on wheel-track effects in Colorado are highlighted along with initial attempts to predict their effects on hydraulic properties. The greatest challenge for the future is improved process-based prediction using a systems approach to include tightly coupled process interactions in space and time. (C) 2003 Elsevier Science B.V. All rights reserved.