Submitted to: Crop Pest Management Workshop Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 5, 2000
Publication Date: N/A
Technical Abstract: Soil compaction prompts a focus on bulk density, but soil water relations and impaired internal drainage are most often the primary result of soil compaction. To find where compaction has impacted soil water relations in the field one must do profiles of bulk density and/or penetrometer cone index to identify where compaction may be expected to change Ksat and related hydraulic properties. Ksat and other hydraulic properties must be measured in undisturbed field cores. Bulk density and Ksat (a good index of soil drainage) are not easily related even within a soil texture unless additional water relations are used in the relation. It is usully easier to measure Ksat directly. Bulk density and Ksat can be spatially controlled in horizontal and vertical dimension by traffic and tillage tool system. This spatial control must be recognized and used to improve tillage systems and internal drainage. Conservation or reduced tillage systems are more sensitive to compaction than the traditional full-width moldboard system. Management of traffic and tillage tool are thus more critical. There are new systems available (i.e. strip and ridge-till) to control/reduce compaction in conservation tillage. We may be relying too heavily on measured soil hydraulic properties on Experiment Station land -- more farm fields must be sampled as deep as 80 cm. More measured and predicted water contents (simulated water movement) over time near the surface are needed as related to traffic, tillage, and tile drainage responses to rainfall variations. An impaired internal drainage can have an impact on soil wetness near the surface such that plant diseases have a more favorable environment. This could be more important in reduced tillage systems as suggested by recent publications.