Residual Removal Effects on Soil Properties within a Spatially Variable Field

Authors: Wienhold, Brian; Wilhelm, Wallace

Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/15/2008
Publication Date: 7/21/2008
Citation: Wienhold, B.J., Wilhelm, W.W. 2008. Residual Removal Effects on Soil Properties within a Spatially Variable Field. International Conference on Precision Agriculture Abstracts & Proceedings [CD-ROM].

Interpretive Summary: Residue remaining in a field after crop harvest is being considered as a feedstock for biofuel production. It is uncertain what effect removal of crop residue will have on the soil resource. Greater wheel traffic associated with residue removal increases the potential for soil compaction. Residue removal exposes the soil to wind and water erosion and removes nutrients contained in the residue. Finally, there is uncertainty about the amount of residue that must be retained to maintain soil organic matter status. The situation is more complicated at the field scale as soil susceptibility to degradation and erosion and soil organic matter status vary within a field. Existing information was used to calculate residue requirements for erosion control and maintenance of soil organic matter for several soils used for corn production. In addition, a study was initiated in a field exhibiting topographic variation to compare soil organic matter and corn production in strips where residue was either retained or removed. At the beginning of the study soils were intensively sampled. Each year corn grain and residue production will be determined. After five years of residue removal soils will be resampled and changes in soil properties determined.

Technical Abstract: Crop residue has been identified as a feedstock for biofuel production. Biofuel proponents often label crop residue a waste and fail to acknowledge its importance to maintaining critical soil functions. Crop residue provides physical protection from water and wind erosion, serves as a source of energy and nutrients for soil biota, and is essential for maintaining soil aggregation, organic matter content, and nutrient cycles and availability. Crop residue required to sustain soil function is dependent on inherent soil properties, management, and the conservation goal. For many fields, crop residue requirements will vary spatially. Crop residue requirements for erosion protection and maintenance of soil organic matter content for several soils used for corn production in the north central US were assessed. This assessment calculated corn residue requirements for soils under continuous corn or a corn – soybean rotation and under tillage or no-tillage. This assessment determined that greater amounts of residue are required to sustain soil organic matter than to protect against erosion; greater residue must be retained in tilled systems than in no-tillage systems; and residue requirements are greater in a corn – soybean rotation than in continuous corn. A second study was initiated in 2006 comparing soil properties and crop response to residue removal within a spatially variable field near York, NE. Eight 24-row strips representing four replications of two treatments (residue removal vs. residue retained) were established in a ridge-tilled irrigated continuous corn field. An apparent electrical conductivity (ECa) survey was conducted and the ECa survey used to select 20 soil sampling locations within each strip. Soils were analyzed for soil organic matter, particulate organic matter, labile carbon, microbial biomass carbon, and pH. Annual grain yield and residue removal rates are also being measured. Soil samples will be collected again after five residue harvests and soil properties compared.