1a. Objectives (from AD-416):
In coordination with the corn stover removal field trials and residue removal tool development, support the development and implementation of modeling methods for assessing the soil compaction impact of agricultural residue removal on continued productivity and soil health.
1b. Approach (from AD-416):
Soil compaction has been identified as one of six limiting factors which collectively define the sustainability of agricultural residue removal for bioenergy production. The soil compaction limiting factor is challenging to calculate quantitatively and at the scale being modeled through the Residue Removal Tool. The impact of soil compaction results from complex interactions of many independent factors. There currently is no model for soil compaction that exists in the mold of the other limiting factor models. Subsequently, the goal of the Residue Removal Tool development team is to implement numerical relationships that consider the soil compaction limiting factor as effectively as possible at the field and sub-field scale. The scope of this project is guiding the development and implementation of those numerical methods within the tool framework. The following list represents the tasks that need to be completed to effectively consider soil compaction impacts within the Residue Removal Tool framework: 1) Review existing models and numerical methods for estimating soil compaction on agricultural lands; 2) Determine additional input data, beyond the current dataset utilized in the tool that will be required to model soil compaction; 3) Build the data and computational method map for soil compaction modeling within the tool framework; 4) Complete the integration of the soil compaction modeling methods within the tool. Work will begin reviewing existing models and numerical methods for soil compaction immediately upon funding receipt. The primary deliverable for this task will be a white paper representing the viable approaches for calculating soil compaction impacts from residue removal within the current Residue Removal Tool schemas. The white paper will begin the work toward understanding the additional input data that will be needed within the tool to perform the soil compaction calculations. This effort will continue into year two of funding, and lead to the development of the data and computational method map as outlined in task three.
3. Progress Report:
Effects of crop residue removal on soil compaction. Pedotransfer functions for predicting the effects of change in soil organic matter on soil water content and soil strength have been identified and tested against data from a Weld loam and a Rago silt loam from Akron CO. The functions allow the prediction of the boundaries for the Least Limiting Water Range and can be used to evaluate effects of changing soil organic matter content due to crop residue removal on soil physical health. A draft of a white paper describing the pedotransfer functions and recommendations for their use in predicting changes on soil physical properties due to crop residue removal is being prepared. This is the final year of the project.