"Wise land use is simply an adaptation of nature's conservation and flood control methods to the conditions of advanced cultivation."
--H. A. Wallace
Deep Roots and Continuous Living Cover
Prior to Euro-American settlement, much of Iowa was covered by grasslands, oak savannas, and riparian woodlands. These plant communities were diverse, perennial, and deep-rooted, and they provided nearly continuous living cover. Consequently, they produced fertile soil, prevented erosion, filtered and retained water, and supported an abundance of birds, insects, mammals, and other animals. Conversion of most of this vegetation to two annual crops, corn and soybean, has had strong negative impacts on soil, water, and wildlife.
Can strategic placement of small amounts of perennial vegetation within a matrix of annual row crops provide large improvements in soil and water quality and wildlife conservation, while maintaining production and profitability? I think so. My research group studied the agronomic, economic, and environmental consequences of three approaches for adding diversity, deep roots, and more cover to the current agricultural landscape: (1) integrating forage legumes, small grains, and ruminant livestock into corn and soybean based cropping systems; (2) using mixtures of perennial prairie species as feedstocks for biofuel production; and (3) weaving strips of reconstructed prairie vegetation into corn and soybean fields as conservation buffers. These topics have been addressed in the Marsden Farm experiment, the Consortium for Cultivating Human and Naturally reGenerative Enterprises (C-CHANGE), and the Science-based Trials of Row-crops Integrated with Prairies (STRIPS) project, respectively.
Weed Ecology and Management
Herbicides are the most heavily used class of pesticide in agronomic crop production. Current problems with environmental contamination by herbicides and the evolution of herbicide resistance in populations of multiple weed species have led to a search for new approaches for weed management that are both effective and environmentally benign.
Ecology forms the basis of strategies for managing weeds with less reliance on herbicides and cultivation. Investigations by our group focus on understanding how crop rotations, compost and manure amendments, insect and rodent seed predators, and different cultivation and herbicide regimes affect crop-weed interactions and weed population dynamics. Special attention is being directed toward better understanding the dynamics of weed seedbanks.
A recent publication reporting what I learned with colleagues from the University of Minnesota about the effects of different crop rotation systems and herbicide regimes on weed control, crop productivity, profitability, environmental quality and human health can be accessed here.
Outreach and Implementation
Communicating scientific findings with the public, especially with members of the agricultural community, is a high priority. The STRIPS project has been especially successful in engaging with farmers and landowners as they themselves serve as teachers, investigators, and advocates for improved conservation and environmental protection practices.