2011 Annual Report
1a.Objectives (from AD-416)
1. Determine the effects of tillage, corn residue removal, cover crop, and crop rotation on soil physical, chemical, and biological properties including greenhouse gas and soil carbon dynamics in conventional and organic agricultural production systems. Contribute to multi-location projects including Greenhouse gas Reduction through Agricultural Carbon Enhancement network (GRACEnet) and Renewable Energy Assessment Project (REAP).
2. Assess soil-landscape rehabilitation (movement of soil from areas of net accumulation to areas of net soil loss) as a means of improving soil characteristics, soil productivity, farm profitability, pesticide persistence and mobility, and soil erosion.
3. Develop crop rotation, soil nutrient cycling, corn residue removal and pest management practices that improve farming efficiency (increase unit output/unit input), and manage soils in a holistic approach to improve crop yield and quality while maintaining or reducing production inputs.
1b.Approach (from AD-416)
The need to produce ever-increasing amounts of food, feed, fiber, and biofuel feedstocks for a growing world population, increased production costs, and fluctuating commodity prices are difficult challenges faced by our customers. Additionally, potential global climate effects on the local environment, degradation of soil resources, and depletion of non-renewable resources (e.g., oil and phosphorus fertilizers) are important concerns of farmers in our region and throughout the U.S.
To answer these challenges and concerns, we are conducting research to optimize soil, crop and pest management practices and to synthesize them into integrated production systems that are economically sound, environmentally sustainable, and provide maximized production efficiency. This interdisciplinary project aims to define, for the unique conditions of the northwest Corn Belt and northern Great Plains, the relationships between soil, crop, and pest management and the conservation of the soil resource. This work is essential for the development of integrated production systems and sustainable agriculture in this region.
Transfer of these integrated production systems to our customers through fact sheets, management guides, field day presentations, and other mechanisms will lead to increased production efficiency, improved soil quality, rehabilitation of degraded soil resources, improved profitability, and reduced risk.
This project continues 5447-12620-002-00D.
To evaluate the impact of crop production practices on greenhouse gas emissions, we conducted a series of studies to quantify trace gas flux from cropland. The fifth year of measuring greenhouse gas (CO2, CH4, N2O) fluxes was conducted as planned on plots under alternative rotational management. A third year of measurements was collected on plots under differing corn residue removal levels. This research is part of the nationwide ARS cross-location projects: REAP and GRACEnet.
Mycorrhizal fungi are key components of soil biological quality and influence crop phosphorus nutrition. Two one-year studies were completed to examine the effect of cover crops on mycorrhizal fungi and their provision of P to following corn crops. These studies were conducted in producers’ fields; a second year of a three-year study with similar objectives on research farm plots is underway.
Crop growth can be suppressed in fields when high quantities of corn residue remain on the soil surface. To examine this perceived trend, we grew dry pea, spring wheat, and red clover at two levels of corn residues. A tilled (no residue) treatment was included for comparison. Yield (forage for red clover; grain for dry pea and spring wheat) of all crops was less when corn residues remained on the soil, especially in the high residue treatment. Averaged across crops, yield loss was 26% at the high residue level and 14% at the low residue.
To evaluate intra-landscape soil movement as a means to improve soil properties and crop yield, we completed monitoring as planned at on-farm sites in two states. This work is showing that crop yields can be increased by 10 to 90% by adding 6 inches of high-quality topsoil to eroded land. To assess potential impacts of soil movement on herbicide effectiveness and off-site transport, we initiated laboratory studies of herbicide retention and degradation in eroded and rehabilitated soils.
As part of a national research project (REAP) research was continued to evaluate the impact of removing corn residue on soil quality. Data from the Brookings SD study indicate that after four rotational cycles, soil organic carbon and other short-term indicators of soil quality were decreasing. Additionally when corn residue is removed, microbial activity is reduced, key pools of soil carbon are not being replenished, and the physical protection the corn residue affords the soil is eliminated, resulting in an observed breakdown of the soil structure increasing susceptibility to wind and water erosion. The results of this study are providing regional data for a national assessment of the impact of corn residue removal on sustained productivity.
Long-term field experiments to develop crop rotations that optimize soil quality and productivity under no-till soil management were continued. Rotations that included perennial forages (e.g. alfalfa) increased soil carbon accumulation (250 kg/ha/yr) while those with annual forages (e.g. oat/pea hay) had lower rates of carbon accumulation (10 kg/ha/yr). Thus, forage crop types used in rotation can have dramatically different effects upon soil carbon accumulation and soil quality.