The Iowan landscape is largely dominated by a simple rotation of rainfed maize (Zea mays) and soybean (Glycine max). This rotation of continuous summer annuals leaves the soil vulnerable to erosion and nutrient leaching, negatively impacting both soil health and the environment. Research has shown diversifying these systems can ameliorate these side effects, while also supporting higher and more stable maize yields. The higher yield stabilities may help convince farmers of the production value of diversification, in addition to its environmental benefits. However, although decreased yield variability is likely associated with changes in water dynamics, the exact mechanisms for yield stabilization remain unclear. Iowa precipitation is strongly seasonal, meaning maize regularly experience some degree of summer drought stress during yield-defining growth stages. Diversified systems may improve soil quality by increasing organic matter and/or improving soil structure. This could increase the water holding capacity of the soil, thus reducing water stress during critical maize growth periods. The amount of plant-available water a soil can hold is commonly assessed by creating a soil-water retention curve (SWRC), wherein the amount of water held in the soil at various negative pressures is measured. A SWRC provides an excellent quantification of a soil’s functionality with regards to water. However, the measurements are time intensive and require specialized equipment, making them inaccessible to most farmers. This project will collaborate with farmers to create SWRCs for on-farm side-by-side trials testing differing degrees of cropping system diversification. The results will be shared with farmers and researchers to illustrate how diversification can .affect a soil’s ability to buffer variability in precipitation. Farmers will use this information to evaluate whether cropping system diversification can enhance functional aspects of their soil while simultaneously improving environmental quality.
Project objectives from proposal:
Through this project, farmers and researchers will learn how diversifying a maize/soybean system affects the soil’s ability to hold water. Farmers will increase their engagement with diversification-based on-farm research. Researchers will expand their knowledge on whether diversification-induced soil changes seen in university experiments are mirrored in side-by-side comparisons on farmer’s fields. In the long term, this project will help to increase farmer adoption of cropping system diversification to build soil quality, reduce their exposure to weather related production risks, and improve the environmental footprint of Midwestern agriculture.