The Efficacy of Fall Cover Crops as They Relate to Stream Habitat & Water Quality

State: Indiana

County: Wabash

Water Bodies Affected: Beargrass Creek, Pawpaw Creek, Eel River

This study will provide valuable data regarding the efficacy of fall cover crops and best management practices as it relates to stream water quality (nutrient and sediment loads), stream habitat, and biological integrity of agricultural streams.

Historically, many soil and water conservation practices have focused on slowing the discharge of soil and nutrients after they have become entrained and moving from fields. Examples include: two-stage ditches, grass waterways and buffer strips. More recently there is a growing interest in technologies that keep soil and nutrients in place where they can best be utilized by crops. One such practice is the use of cover crops during those portions of the year when a crop is not in production (such as corn or soy beans). Cover crops have not been widely used by farmers, but rather are somewhat randomly distributed across the landscape making it difficult to quantify their effectiveness. In an effort to better understand the economic and ecological benefits of cover crops, the objective of this project is to maintain or advance agricultural productivity through the examination of two headwater watersheds (not to exceed 3,000 acres). One watershed will be treated with as many acres as possible with fall cover crops over a five year period while the second will be left under “normal” agricultural practices as determined by the individual operator. This experimental design will provide valuable data in regards to the effectiveness of fall cover crops both in terms of nutrient and sediment export, but also to document if there is any changes in the biotic community (fish, mussels and other invertebrates).

The two watersheds selected for this study are both tributaries of the Eel River in northern Indiana. They include the upper portions of Beargrass Creek and the upper portion of Pawpaw Creek. Both of these streams are currently being monitored in the lower reaches near the confluence with the Eel River as part of a much larger watershed study being conducted by Manchester University on the middle portion of the Eel River. Cover crops will be used across as much of Beargrass Creek watershed as possible while the Pawpaw Creek watershed will be left in a conventional production strategy with no cover crops applied. Individual streams within each watershed will be carefully monitored with time-integrated discrete water samplers during the months of May and June. Grab samples will be collected at least monthly during all other months. Water will be analyzed for total phosphorus, Nitrate-nitrogen, and suspended sediment (turbidity and gravimetrically). In addition, stream discharge will be calculated to determine nutrient and sediment loads. Rainfall along with air and water temperature will also be recorded once each 30 minutes. Stream habitat will be quantified with the QHEI and the fish community will be evaluated and monitored using the Index of biological integrity for the Easter Cornbelt Plain. Mussels will be surveyed in each of Beargrass Creek, Pawpaw Creek and the mainstem of the Eel River. Six sites will be monitored in Beargrass Creek and eight sites will be monitored in Pawpaw Creek. The three long-term monitoring stations in the Eel River will also be quantified.