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Dec. 2, 2010 Volume 32, No. 14

With model, researcher goes back in time to study impact of farming


Simulation can improve conservation efforts

Uunderstanding the impact of agriculture on over time is tricky when you don’t have much information about what the land was like before it was farmed.

But a University of Missouri graduate student found a way to go back in time to revisit fields in their pristine state by creating a computer model that can simulate the effects of 100 years of farming on claypan soils.

Ashish Mudgal, who recently completed his doctorate in soil science at MU, took detailed measurements of the soil properties of two 80-acre claypan fields — one, a native prairie that had never been farmed; and another that had been under cultivation for more than a century.

Mudgal incorporated the data, along with satellite images and aerial photographs taken between 1930 and 1990, into a model developed by researchers at Texas A&M University called APEX (Agricultural Policy Environment eXtender), which estimated changes in runoff, erosion, and the flow of sediment, nutrients and herbicides.

The model showed that, after 100 years of simulated row-crop farming, the average annual runoff of the herbicide atrazine increased 82 percent. Meanwhile, corn yields declined by 39 percent and soybean yields fell by 75 percent.

The study also suggests that on claypan soils, the farmland that often presents the greatest environmental challenges also tends to be less productive.

 “These results show that the restoration of agricultural lands would be beneficial not only to enhance crop yields but also to reduce nonpoint-source pollution,” Mudgal said.

Findings from simulations like this can help farmers, policymakers and conservation agents make better decisions to reduce the environmental impact and enhance productivity of farmland.

Mudgal’s study was funded in part by the Conservation Effects Assessment Project (CEAP), a long-range national effort by the U.S. Department of Agriculture to measure the impact of conservation practices on agricultural land and water quality.

Although conservation practices can’t replace soil that has been lost over time, they can return properties such as the soil’s water infiltration capacity to something closer to the original state. Studies such as Mudgal’s can help CEAP devise scientifically sound tools to gauge the effectiveness of conservation practices, which are designed to control erosion, maintain soil productivity, protect watersheds and enhance wildlife habitat.

Such tools can provide guidance for bringing retired land back into production and for targeting conservation efforts where they can do the most good, Mudgal said.