Interactions of VAM fungi, pesticides and crops

V esicular arbuscular mycorrhizal fungi (V AM) are beneficial root symbionts of most crops, including corn and soybeans. These fungi colonize plant roots, facilitating nutrient ex­ change between the plant and the fungus. The plant supplies carbon for fungal growth; in turn, the VAM enhances uptake of relatively immobile nutrients such as phosphorus (P). The network of external fungal filaments, or hyphae (see photos below), extends outside the root up to several centimeters in the soil, allowing the fungus access to soil P otherwise unavailable to the plant

Theme Overview: Agriculture and Water Quality in the Cornbelt: Overview of Issues and Approaches

Resource /Energy Economics and Policy, Q25,

Coupling Manure Injection with Cover Crops to Enhance Nutrient Cycling

Large-scale hog (Sus scroja) production is a major agricultural enterprise in the Midwest. Large numbers of confined hogs produce about 50 million tons per year of swine manure in Iowa alone. Rapid expansion of concentrated animal feeding operations (CAFOs) has resulted in increased concentrations of manure nutrients in surface waters which contribute about 15% of the total nitrate load in the Mississippi River Basin. Producers are being encouraged to develop manure management practices that fulfill crop production requirements, while minimizing the potential for environmental pollution. The most commonly used manure management practice in the Midwest involves fall application to land where corn (Zea mays L.) will be grown in the subsequent growing season. Fall planted annual cover crops can capture manure nutrients and immobilize them in plant biomass, subsequently reducing the potential for nutrient loss through run-off or leaching. Decomposition of cover crop residue the following spring may help synchronize manure N availability and corn N uptake, improving nutrient-use efficiency within the crop rotation

Environmental Benefits and Management of Small Grain Cover Crops in Corn-Soybean Rotations

These slides offer research results on cover crops

Estimating Atrazine Leaching in the Midwest

Data from seven Management Systems Evaluation Areas (MSEM) were used to test the sensitivity of a leaching model, PRZM-2, to a variety of hydrologic settings common in the Midwest. Atrazine leaching was simulated because the use of atrazine was prevalent in the MSEA studies and it frequently occurs in the region\u27s groundwater. Results of long-term simulations using regional and generalized input parameters produced ranks of leaching potential similar to those based on measurements. Short-term simulations used site-specific soil and chemical coefficients