Agricultural Landscape Where We Work

Our group works in the agricultural landscape of the upper Midwest, which has not been well studied from a biogeochemical viewpoint. Until recently, past research in this landscape has focused on crop production with the emphasis on improving soils and drainage to benefit agriculture. Little attention was paid to the sustainability of this landscape, and on environmental impacts of this intensive agriculture. We examine all aspects of nutrient cycles in agriculturally dominated watersheds, including but not limiting our studies to crop production, soil nutrient cycling, leaching losses through tile drainage, and transport and impacts of nutrients in streams/rivers of Illinois. Because watersheds in our area export on average about 30 kg N/ha/yr as nitrate, we monitor rivers and put our results in the context of watersheds. Past work examined the fate and effects of nutrients such as N and P added to the aquatic system. Current projects focus on conservation practices that can be used to reduce nutrient losses, such as fertilizer management, cover crops, bioreactors, constructed wetlands, complex rotations, and drainage water management. The upper Midwest is the major source of N to the Mississippi River, a primary cause of hypoxia in the Gulf of Mexico. We need to continue to produce crops in this region, but must better understand nutrient biogeochemistry and use this knowledge to develop more sustainable production methods that minimize environmental impacts.

Fertilizer dominates N and P inputs to this landscape, with 50 to 75% of N fertilizer applied in fall.	Watersheds are 85 to 95% corn/soybean, with biological N2 fixation adding large amounts of reactive N to the landscape.	Tile drainage was used to allow these high organic matter Mollisols to be farmed, with most first installed during the 1880s. Streams were channelized at the same time.
Ammonium fertilizer undergoes nitrification and can be transported to streams through the tile system.	This is the outlet of the upper Embarras River watershed at Camargo during high flow in spring, the location of a USGS gaging station.	We have sampled the river since late 1993, with weekly to daily collection, which allows us to calculate loads and assess long-term changes.

Last Updated February 1, 2016