Location: Soil Management Research2011 Annual Report
1a. Objectives (from AD-416)
1. Determine crop residue needs to protect soil resources and identify management strategies that enable sustainable production of food, feed, and biofuel. 2. Develop options for managing crop systems to reduce GHG emissions and increase C storage. 3. Assess bulk movement of soil within fields as a means of improving soil characteristics, soil productivity, farm profitability, pesticide persistence and mobility, and soil erosion. 4. Evaluate impacts of environmental changes (water, CO2, temperature) on traditional, biofuel and alternative crops to develop a model-based risk assessment of crop production under the most likely medium-term (10-30 yr) climate change scenario for the upper Midwest.
1b. Approach (from AD-416)
The project will generate information for balancing crop production goals with harvest of biomass for biofuel; develop management options to decrease greenhouse gas emissions and increase C storage in soil; evaluate an approach to remediate eroded soils; and provide information on crop response to climate change. Plot and on-farm approaches will be used to assess changes in soil carbon, greenhouse gas emission, soil quality indicators and production as a consequence of crop biomass harvest. This information will be identified locally and contribute to the national GRACEnet database on greenhouse gas emission and carbon storage. It will also contribute to national recommendations and guidelines through the REAP project. A farm-scale evaluation of field-scale soil movement (conducted to decrease soil spatial variability) will be used to develop improved management practices that restore productivity to eroded soils. This information will improve predictions of water and agrochemical transport in eroded soils, the response of soil biological communities to soil disturbance, and the short-term impact of soil erosion on soil C dynamics and soil productivity. This project will identify physiological and biochemical markers to develop or select cultivars adapted to climate change to develop environmentally- and economically-sustainable and diversified cropping systems that reduce risk and increase the probability of profitable crop production.
3. Progress Report
To meet the expanding demands for food, feed and fuel, strategies are needed to simultaneously preserve productivity, protect the natural resources, mitigate Greenhouse Gas (GHG) emission, and provide agricultural resilience from potential climate change impacts. Substantial progress has been made toward obtaining the overall goal of this project, developing soil and crop management systems that sustain agricultural production, readily adapt to climate change, minimize GHG emission, sequester carbon, and safeguard soil productivity while protecting environmental quality in the upper Midwest. Conservation-based guidelines and compensatory strategies for addressing soil management risks associated with residues harvested were established; thus, maintaining and protecting soil resources. Measurement and analysis of greenhouse gas emission from agricultural sources continue. A three-year study comparing effect of harvesting only grain or harvesting grain and stover on greenhouse gas emission was completed. Data summarization and analysis from this three-year study is in progress. Likewise, the second monitoring year was completed and the third and final year initiated in a study comparing emission from alternative managements to a corn/soybean rotation with all residues returned. Crop productivity and biomass production data were collected from all plots. These experiments will improve biomass management and safeguard soil productivity so that soils can indefinitely supply food, feed, fiber, and fuel. Furthermore, they will identify strategies for reducing agriculturally-related greenhouse gas emission without sacrificing productivity. Considerable progress has been made in evaluating environmental changes (water, CO2, temperature) on traditional, biofuel and alternative crops to develop a model-based risk assessment of crop production under the most likely medium-term (10-30 yr) climate change scenario for the upper Midwest. For example, it was determined that when switchgrass ecotypes were moved from near ideal to low growth temperatures they did not acclimate photosynthetically, but instead they adjusted the way they made and used sugars, such that some grew better than others at cooler than ideal temperatures. We found that a southern variety produced more biomass than northern varieties, even at low temperatures. This information will aid in developing and improving more productive Switchgrass for bioenergy production. We completed a three-year study using field-grown and farmer-managed sugar beet, which identified leaf and root traits that affected sugar content throughout the growing season. The findings may help farmers and agronomists improve management practices that increase carbon storage in roots; maintain adequate, but not excessive, levels of nitrogen in the developing leaves and roots; minimize the variability in, and optimize root sugar content.
1. Conservation-based biomass feedstock harvest recommendations. Crop residues are a potential renewable bioenergy feedstock that can produce power, heat and transportation fuels. Crop residues refer to the non-food portion of a crop that remains after grain harvest that protects soil from erosion and builds soil organic matter. Guidelines or recommendations are needed when deciding where, if, and how much residue needs to remain on the land and how much may be harvested. ARS researchers at Morris, Minnesota, developed recommendations for conservation-based biomass feedstock harvest, which were used to write university and Natural Resources Conservation Service (NRCS) factsheets, and were presented at workshops and field days. These guidelines provide decision tools to producers, consultants, extension and NRCS, and industry for determining where, if, and how much crop residue can be harvested. Furthermore, research-based recommendations were developed for safeguarding soil productivity if residue is harvested so that soils can indefinitely supply food, feed, fiber and fuel.
2. Physiological basis for differential productivity in switchgrass ecotypes. Switchgrass, a native grass in the U.S. has gained large popularity as a biomass crop for bioenergy. It is adapted to a wide range of environments; however, its productivity declines the further north it is grown within its native range. ARS researchers at Morris, Minnesota, discovered that when moved from near ideal to low growth temperatures, varieties of switchgrass adapted to different parts of the U.S. did not acclimate photosynthetically but instead they adjusted the way they made and used sugars such that some grew better than others at cooler than ideal temperatures. We found that a southern variety produced more biomass than northern varieties, even at low temperatures. This was partly because it made more sugar for growth (sucrose) than storage (starch) than other varieties did. The information greatly helps other scientists, especially plant geneticists, developing more productive switchgrass varieties for bioenergy.
Johnson, J.M., Morgan, J.A. 2010. Plant sampling guidelines. In: Follett, R.F., editor. GRACEnet Sampling Protocols. Available at http://www.ars.usda.gov/research/GRACEnet. p. 2-1 - 2-10.