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 Agriculture plays a crucial role in sustaining the health, nourishment and economy of the world’s population. At the same time, some agricultural practices can disturb the environment in ways that affect the quality of our natural resources – including soils, waterways, and even the air we breathe.
At SAGE, we focus on examining the interactions between land management, vegetation, climate, soils, and hydrology to better understand how human activity has changed the cycling of carbon, nitrogen, and water in the soil-plant-atmosphere system during the past century. We are specifically interested in how we might best manage agricultural land in the future to maximize food production while minimizing environmental damage. Our work combines field research studies based in the Midwest with larger-scale datasets and ecosystem modeling techniques to examine the behavior of agricultural systems across a variety of scales – ranging from individual fields to the regional scale.
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Agricultural Systems from Local to Regional Scales
SAGE scientists study the production and environmental impacts of agricultural systems at two scales:
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• Looking at the Individual Farm SAGE scientists are working with colleagues in the Department of Soil Science and Space Science and Engineering Center (UW-Madison) to develop numerical models of Midwest production systems that can be applied by farmers at the precision agriculture scale. The ultimate goal is to help determine the most economical and environmentally sound methods of nitrogen and phosphorus fertilizer application. The modeling system (called the Precision Agricultural Landscape Modeling System or PALMS) enables farmers to study how weather, variable topography, soil conditions, and management across an individual field – on a row-by-row basis – impact crop yield, soil nutrition, drainage, and field runoff. The testing of these precision models has relied heavily on field experiments based in Wisconsin, Illinois, and Minnesota.
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Model simulations of corn yield (bu/acre) variability in a topographically diverse field in southern Wisconsin in the year 2000.
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Model simulations of potential changes (1990s compared to the 1960s) in optimal corn planting date (days) across the Corn Belt.
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• Looking at the Regional Scale In order to gain a better understanding of how widespread agricultural land management in the U.S. Corn Belt is impacting crop production as well as soil carbon storage and water quality, we integrate large-scale datasets of soil type, and changes in climate and vegetation cover during the past century with our agricultural modeling tools. This allows us to examine how region wide agricultural land management has contributed to such outcomes as significant nitrate loading to the Mississippi River and the development of the Gulf of Mexico “dead zone”, or how much carbon has been released to the atmosphere when great expanses of tallgrass prairie were converted to production systems. We can further examine how crop yields may change in the future given future changes in climate and atmospheric CO2 levels, limitations of crop physiology, and potential restrictions on excessive fertilizer applications. We are ultimately concerned with the overall sensitivity of the larger region and continued availability of ecosystem services.
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Sixteen year old Conservation Reserve Program prairie restoration study site near Blue Mounds, Wisconsin in June, 2003.
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Conservation Reserve Program food plot (corn) adjacent to prairie restoration in western Dane County.
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Measuring soil surface CO2 respiration on Conservation Reserve Program land immediately following a prescribed burn in April, 2003.
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Prairie Restoration and Carbon Sequestration
We also focus on how varied soil conservation techniques, specifically prairie restoration in southern Wisconsin – store organic matter in the soil and, in return, remove carbon dioxide from the atmosphere. This process is termed “carbon sequestration” and is often suggested as a means to offset greenhouse gas emissions resulting from our reliance on fossil fuels.
Carbon sequestration offers many possible benefits to farmers, other landowners, and entire ecological and biological systems because soil fertility is increased, soil erosion and sediment runoff is reduced, biodiversity is enhanced, and additional wildlife habitat is created. In addition, there are potential economic advantages for farmers, corporations, and utilities in trading “carbon credits”.
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Currently, we are gauging the economic and ecological viability of carbon sequestration for prairie restorations in southern Wisconsin. We have specifically targeted studying carbon cycling in prairie restorations as part of the Conservation Reserve Program (CRP) – and have quantified typical rates of carbon sequestration. Typical soil carbon and nitrogen storage has been quantified in approximately 130 sites in southern Wisconsin that include prairie relics, wetlands, and row-crop systems in addition to CRP land and other private prairie restorations. Most recently, we have established a long-term carbon cycling study at the location of the world’s oldest prairie restoration (Curtis Prairie at the UW-Madison Arboretum) to help gauge restoration success.
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Compass plants in Curtis Prairie at the University of Wisconsin-Madison arboretum in July, 2004.
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Measuring leaf area index in Curtis Prairie at the University of Wisconsin-Madison Arboretum in July, 2004.
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We are collaborating closely with utilities, corporations, state agencies, and environmental organizations in the region, among them UW-CALS, NASA, MG&E, SC JOHNSON, USDA-NRCS, WI-DNR, and the INTERNATIONAL CRANE FOUNDATION.
Our ultimate goals in this area of research are to better understand the effect of different vegetative communities on rates of soil carbon accumulation, the costs of verification, and to quantify the total amount of carbon being sequestered to help assign “carbon-credits”.
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