Recycling Nutrients with Cover Crops to Decrease Hypoxia/Eutrophication while Promoting Sustainable Crop Production
Agricultural systems that mimic the natural environment tend to be more sustainable while high input production systems have more problems with eutrophication and hypoxia. Nutrient losses occur due to a lack of continuous living crops to absorb or recycle excess nutrients. Continuous living covers more closely mimic a natural system. No-till farming with a cover crop improves the profitability of agriculture because fewer nutrients are wasted through erosion, leaching, and volatilization; and more nutrients are actively stored long-term in soil as organic forms. The sustainability of cropping systems is directly linked to soil organic matter (SOM) which is a core indicator of soil quality.
A goal of 5,000 acres of cover crops in the Upper Wabash and Grand Lake St. Marys River Watershed.
Cover crop plots initiated at Ohio State University (OSU) South Piketon and Hoytville research branches.
Approximately 8,000 acres were planted to cover crops in three watersheds (Upper Walbash, Grand Lake, and St. Mary’s).
Cover crop data was collected for one years from OSU South Piketon and Hoytville research stations with two additional years of data being collected in 2011 and 2012.
Impacts and Contributions/Outcomes
Farmers have started using cover crops to soak up manure nutrients. Approximately 21% of Grand Lake Watershed has cover crops (9,300 acres) and 25% has green covers (from hay or wheat for winter wheat for grain.) Approximately 50% or 150 out 300 farmers in the Grand Lakes St. Marys Watershed are now trying cover crops on at least one field. Farmers are saving fuel and tying up nutrients by using the cover crops resulting in less manure nutrient loss to Grand Lake St. Marys.
Preliminary research with grass cover crops show that the cover crops may absorb and tie up as much as 70% of the soluble nitrogen in the soil and as much as 20 pounds of soluble phosphorus. Based on 5,000 gallons of swine manure with 90#N-80#P-70#K, the cover crops absorbed $33 per acre of manure nutrients and at 10,000 gallons swine manure (180-160-140) absorbed $44 worth of swine manure nutrients. Similar results were found for dairy manure 5,000 gallons (100-75-75) or $36 and 10,000 gallons (200-150-150) at $64 per acre.
Approximately 40% or 120 out of 300 farmers in the Grand Lake St. Marys watershed have at least tried cover crops. Approximately 8,000 acres or 4% of all acres in Mercer County (200,000 total acres) are using cover crops. About 3-5% of farmers in the western half of Ohio are using cover crops or experimenting with cover crops. The instructor/graduate student has also been involved in promoting cover crops to reduce eutrophication/Hypoxia to Lake Erie and the Mississippi River basin.