Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 28, 2001
Publication Date: July 20, 2001
Technical Abstract: Agriculturalists are very interested in the soil as a medium for plant production. Several methods are used to evaluate soil management affects on soil physical condition, but bulk density is the most common indicator. Bulk density alone fails to give insight on the detrimental effects of soil compaction or to give indications of how to best manage soil compaction. A method that could be more useful to describe the effects of changes in the soil physical condition on plant growth is the Least Limiting Water Range. The LLWR combines several soil environmental factors (water holding capacity, soil strength and soil aeration) into one number that can be used to evaluate soil changes caused by differing soil management. We have been evaluating the LLWR as an indicator of soil condition for both irrigated and dryland conditions in eastern Colorado and show that the LLWR is a good indicator of plant response to the soil environment. For winter wheat, which, in our climate, relies mostly on stored soil water, LLWR alone is a good predictor of crop yield. For corn, which is more dependent on summer rains or irrigation, the best relationship between the soil condition and yield occurs when we account for the actual number of days the plant grows in restrictive conditions. Use of the LLWR by farmers would allow them to better manage soil and water resources for maximum crop production. More work needs to be done to allow rapid collection of the data needed to construct the LLWR for individual soils and to allow precise, spatially variable soil management.