Project Number: 5440-12210-009-00
Project Type: Cross Location

Start Date: Jun 01, 2006
End Date: May 31, 2011

Objective:
1. Determine the amount of crop residues (e.g., corn stover, cover crop) that must remain on the land to maintain soil organic carbon (SOC) and sustain production. Through a series of experiments with factors including tillage and residue removal conducted under several environments, measure biomass production, grain yield, and change in soil organic carbon, and from these measurements estimate the amount of residue needed to maintain soil organic carbon and productivity. 2. Estimate the trade-off between the short-term economic return to growers who harvest crop residues as biofuel or biomass product feedstock versus the long-term benefits to soil, water, and air resources associated with retaining crop residues to build soil organic matter and sequester carbon. 3. Develop robust algorithm(s) to guide the amount of crop residue that can be sustainably harvested as feedstock for biomass ethanol and bio-based products without degrading the soil resource, environmental quality, or productivity. 4. Develop management strategies (e.g., no tillage) supporting sustainable harvest of residue. Modify existing or devise new management practices that allow harvest of stover but maintain production level and soil organic carbon through use of cover crops, organic amendment, or other techniques.

Approach:
Objective 1.1 A series of similar experiments will be conducted at REAP locations with several levels of corn residue removal. Biomass production and grain yield will be measured annually and SOC determined at the beginning of each experiment and again after four years. Regression analysis will be used to estimate the amount of residue needed to maintain SOC and productivity under the soil and climatic conditions at each site. The fitted equations will be used to compute minimum amount of crop residue needed on the soil to maintain SOC and grain and biomass yield. Objective 1.2 Write a summary paper from published literature and unpublished data on the impact of corn residue (stover) removal on future crop yield and soil quality. Objective 2 Analyses will be made using published reports and new data for soil carbon, productivity, and soil quality indicator measurements from experiments at REAP locations (Objective 1.1). The value for stover used for biomass ethanol or other bio-product feedstock will be $33 Mg-1 based on the Billion-Ton Report. The initial value of crop residue as the soil input for sustaining or improving soil quality will be estimated at $5 Mg-1, based on nutrient content. A value will be assigned to changes in soil quality index values that occur with shifts in residue management practices. These factors will be combined in a simple cost comparison to determine the value of crop residue as soil input compared to a biomass energy feedstock. Objective 3 Initial approximations of the amount of crop residue that must remain on the soil for sustainable production will be based on data from the literature and on-going experiments (Objective 1). More robust guidelines for residue retention will be developed using the soil organic matter (SOM) model, CQESTR. The model is being enhanced and refined in five phases, including recalibration and revalidation, as part of this project, the GRACEnet project, and parent NP 202 CRIS for Pendleton, OR. Objective 4 Experiments at REAP locations with factors including tillage, cover crops, and residue removal conducted under several environments, and measurements of biomass production, grain yield, and change in SOC will be used to modify or develop combinations of cultural practices that maintain SOC and productivity under different soil type and climatic conditions. Associated CRIS #'s: 3625-12000-012-00D; 6420-12610-003-00D; 5447-12620-002-00D; 5402-12130-008-00D; 5440-12210-050-00D; 3645-12610-001-00D; 3645-11000-003-00D; 5356-12000-008-00D; 3640-12000-007-00D; 3602-12220-006-00D.