Nutrient Management in the Wabash River Basin

Evaluating nutrient management practices

A tractor applying fertilizer to a crop field
Photo courtesy of Lynn Betts, USDA-NRCS

The Project

In 2020, Indiana farmers set a new state record for cover crops, planting an estimated 1.5 million acres, according to the Indiana State Department of Agriculture. Promoted by federal, state, and conservation-minded organizations, cover crops have been touted for their environmental benefits, which include increased organic matter in the soil, nutrient retention, and improved water infiltration. Because of their ability to sequester carbon, cover crops have also been lauded as part of the solution to climate change.

As climate change brings higher annual temperatures and more frequent extreme precipitation to the Midwest, a better understanding of the effects of farm management practices, such as cover crops and fertilizer application rates, is needed to project effective strategies for farm productivity and environmental stewardship.

The Project

Partnering with an Indiana-based farming cooperative in the Wabash River Basin, a team led by former IU Associate Professor Adam Ward collected regular water samples and captured data related to soil, land, weather, climate, farm management practices, and other variables over a three-year period. The collaboration presented the team with a rare opportunity to quantify biological, geological, and chemical cycles on a large-scale farming operation for academic research.

Using this data, the team constructed a high-resolution computational model of not only the farm, but the entire Wabash River Basin as well, simulating the outcomes of various agricultural management strategies and environmental stressors over time.

After simulating the model 100 years into the future, the team focused on quantifying the benefits of cover crops in its initial analysis. This topic is of particular concern within the Wabash River Basin, one of the most concentrated sources of nitrogen pollution in the Mississippi River Valley.

Broadly, the team found that cover crops can positively affect soil, carbon retention, and nutrient loss, among other benefits. However, despite their benefits Ward and collaborators also found the impact can be highly variable depending on factors such as weather, location, and prior growing seasons.

“Cover crops are not a silver bullet,” Ward notes, “but are certainly part of a more sustainable agro-ecosystem in the future”.

Moreover, the team found that benefits are not necessarily constant in time, with some benefits declining in the far future of simulations. This underscores the need for landowners, land managers, and conservation planners to have a firm understanding of the benefits they are aiming to achieve through cover crops and the timeline for achieving those benefits. A paper on these findings is being prepared by the team.

The Path Forward

With a validated model, Ward’s team is now seeking to answer additional questions related to farm management and climate change in the Midwest. Using IU’s high-performance computing systems, researchers are shifting to ensemble modeling—running multiple versions of the same model at once—to project agricultural outcomes. This technique can lead to better predictions than running an individual model and offer insights into resilient farm management practices under a warming climate, information that could guide farmers and policymakers moving forward.

Updated June 7, 2022

Project Data

Data from this study is not yet available to the public.