|Pikul Jr, Joseph|
|Douglas Jr, Clyde|
Submitted to: ARS Workshop on Real World Infiltration
Publication Type: Proceedings
Publication Acceptance Date: 7/20/1997
Publication Date: N/A
Interpretive Summary: Infiltration of water is a fundamental process that controls many of the soil and water conservation goals in American agriculture, yet field measurements are difficult due to variations over time and space even within a farm field. This review of literature reveals that the variation over time is related to the decomposition of crop residues and the formation of water stable aggregates that prevent formation of soil-surfac seals and crusts that lead to stark reductions in infiltration. The review further shows how farmers are changing infiltration according to their use of tillage systems to control crop residue placement. This information should be useful to scientists, in research and action agencies, for searching out soil management practices and improving natural resource assessments.
Technical Abstract: Infiltration is fundamental to soil and water conservation and is sensitive to soil management. The temporal character of surface seal formation and reduced infiltration may well be sensitive to tillage and residue management because decomposition products can control the formation of water stable aggregates. The shift from moldboard plowing to other forms of primary tillage on 94 percent of the wheat, corn and soybean production in United States places the crop residue within 10 cm of the soil surface, where the decomposition products can most effectively modify infiltration. A cause and effect linkage (crop residues to aggregating agents to soil aggregation to seal formation to infiltration) was proposed for systematically evaluating the temporal character of surface seal formation and infiltration. Tillage control on crop residue placement and hydrothermal control on decomposition is generic and useful on a microsite/field/regional scale. Much is known about organic matter-minera soil interaction in sieve sizes ranging from 2 to 2000 microns. Wet aggregate stability is useful to predict Ksat in the simple saturated-flow model of the surface seal, but a uniform procedure (including field sampling, wetting, sieving, and calculated stability index) is needed and is suggested. The field procedure must also have supporting information on porosity distribution. This linkage scheme should be useful for resource assessment as well as site specific prediction.