Location: Integrated Cropping Systems Research2012 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.
3. Progress Report:
Progress was made on all three objectives and their subobjectives. Within subobjective 1a, we completed analysis of data on the effect of corn residue removal and cover crops on soil microbial communities using quantitative PCR of taxonomic groups using soils collected in the fall. Additional soil samples from these plots have been collected to examine annual and seasonal effects on the microbial communities. The final year of a study that examines the ability of cover crops to increase P availability to subsequent corn via enhancement of native AMF is underway. Analysis of research results evaluating the impact of removing corn residue on soil organic carbon quality and quantity were completed and published, following 8 years of removing residue. During FY12, additional soil samples were collected (12 years of residue removal); soil biological indicators will be determined in conjunction with soil physical and chemical properties. Row and forage crop rotation effects on yield, yield quality and soil condition continued for the 16th year. Progress was made in developing analytical methods for inorganic carbon analysis necessary for measuring soil carbon sequestration deep in the soil profile. Within subobjective 1b: FY12 marked the 4th year of measuring greenhouse gas fluxes in plots under differing corn residue removal levels and the 6th year of measuring greenhouse gas fluxes on a biweekly basis in plots under varying crop rotations. Research progress within objective 2, hypothesis 2a: the final year of yield monitoring at both study sites was completed. Soil samples were collected and are being processed for analysis. Samples for soil carbon dynamics study were collected and analyzed for 137Cs and carbon. Data analysis is underway. Laboratory evaluations of the spatial variation in the sorption and dissipation of the herbicides S-metolachlor and saflufenacil were completed. Objective 2, hypothesis 2b: the experimental site was established and monitoring is progressing as planned. Progress completed within objective 3 found that although producers are hesitant to add alternative crops to the corn-soybean rotation because of possible economic penalties, increasing crop diversity can provide ancillary benefits that may compensate for lower gross returns. Results found that dry pea is synergistic to corn, improving tolerance to stress conditions including: 1) corn density needed for optimum yield is 30% lower when following dry pea compared to soybean, 2) lower population of corn produces 25% less after-harvest residues. Crop residues can interfere with seedling establishment of following crops; dry pea yielded 20% less when it followed a crop planted at higher population compared to a lower population (30,000 vs 21,000 plant/ac). Additionally, grass management treatments were completed for the 12th year, grass canopy and soil sampling continued as scheduled. Soil analysis for carbon sequestration in the soil profile continued. New root sampling methods were developed to help understand how canopy management affects rooting depth.
1. Keep your soil covered. Corn residue is being considered as a possible feedstock for biofuels production in the United States. The feasibility of this practice is being evaluated in multiple studies being conducted by the US Department of Agriculture in collaboration with universities in various regions of the United States. Research in Brookings, SD found that removal of corn residue has a negative impact on soil organic matter. The lack of crop residue on the soil surface resulted in decreased soil organic matter and the destruction of soil aggregates which are important for reducing soil erosion, increasing soil water availability to the crop, and nutrient storage. This research, as part of the national effort, can help develop guidelines to define areas of the US where removing corn residue is feasible and harvest rates that avoid detrimental effects on our soil resource.
2. Synergism. A rotation effect of improved growth efficiency. Producers are seeking methods to reduce the need for resource inputs, both to reduce input costs and to protect the environment. ARS researchers at Brookings, SD have observed that some crop sequences can improve resource-use-efficiency of crops. For example, dry pea improves water-use-efficiency of winter wheat; wheat produces more grain with the same water use. Furthermore, synergism among crops increases tolerance of weed interference because of improved resource-use-efficiency. Synergism is more prominent in low-yielding environments due to stresses such as drought. No-till rotations that include synergistic crop sequences are improving land productivity, farm economics, soil health, and resource-use-efficiency in the semiarid Great Plains.
3. Spatial variation in sorption and dissipation is herbicide-dependent. Understanding how soil variation in eroded fields affects herbicide behavior is essential to predict weed control, water contamination, and other intentional and unintentional effects. ARS scientists in Brookings, SD studied the retention and/or degradation of 4 herbicides in surface soils from an eroded prairie landform. Dissipation of all herbicides was unaffected by position within the landscape, but retention was herbicide and position dependent. These results emphasize that consideration of herbicide and soil properties are both important for predicting herbicide fate. These data are applicable for site-specific herbicide management recommendations to avoid water contamination and to maintain good weed control.
4. Soil nitrogen management, soybeans, and bean leaf beetle insect pests. Immature (larval) stages of the bean leaf beetle (BLB) feed on soybean roots and adult beetles feed on soybean leaves and pods. Soil management practices that affect soybean roots and nodules, such as nitrogen fertilizer applications, may affect BLB populations. ARS scientists at Brookings, SD investigated the impact of soil nitrogen management on soybean nitrogen relations and BLB population dynamics. Increased levels of nitrogen in starter fertilizer treatments resulted in increased BLB adult populations under hot and dry growing conditions but not under cooler and wetter growing conditions. These data suggest that starter fertilizer treatments that contain nitrogen may increase BLB populations and intensify the damage caused by this insect pest under certain growing season environments. Soybean farmers who reduce the level of starter fertilizer nitrogen applied to soybeans could decrease BLB populations, decrease the use of insecticides, decrease production costs and increase soybean yield and profitability.Cabrera, A., Papiernik, S.K., Koskinen, W.C., Rice, P.J. 2012. Sorption and dissipation of aged metolachlor residues in eroded and rehabilitated soils. Pest Management Science. 68:1272–1277. DOI: 10.1002/ps.3294.