Nutrient Recycling with Manure and Cover Crops

Eutrophication and hypoxia has been linked to nutrient losses from agricultural fertilizer and manure. Over two-thirds of Ohio swine and dairy manure is applied in the last half of the year, after crops have been harvested. Most NO3-N leaching occurs during the fall and early spring months when the soil is fallow in a corn-soybean rotation. Winter cover crops temporarily immobilize nutrients and prevent NO3-N leaching losses during the winter rainfall period.  Annual ryegrass (ARG), cereal rye (CR), and bare crop land (BCL) was compared using three rates of liquid dairy manure (0, 6,000, 12,000 gallons) applied in 2005-2006. Individual plant biomass N values as high as 5.31% N were found for annual ryegrass and 5.17% N for cereal rye. Using Duncan’s Multiple Range Test, nitrogen treatments (P<.0149) were significantly different with mean values of 4.84% ARG12, 4.56% for ARG6, 4.40% for CR12, 4.39% for CR6, 3.57% CRO. June soil nitrates and total nitrogen treatments (P<.0001), soil depth (P<.0005), and replications (P<.0001) were significantly different but treatment by soil depth interactions were not significantly different. Mean soil nitrate values (mg/kg) were 46.98 ARG12, 38.95 for ARG6, 28.40 for BCL12, 22.46 for BCL6, 21.39 CR12, 20.36 for BCL0, 13.19 CR0, 9.03 for CR6, and 6.82 for ARG0. Annual ryegrass and cereal rye have the potential to absorb manure nutrients, be utilized as forages by livestock farmers, and prevent eutrophication and hypoxia in surface waters.

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James J. HoormanWater Quality Extension Specialist
Ohio State University
hoorman.1@osu.edu


Jim Hoorman is a water quality extension specialist at the Ohio State University with 15 years experience. Jim has been working the last 7 years on keeping manure out of surface water and working to prevent preferential flow and livestock manure violations. The last four years he has started a PHD program researching cover crops and ways to absorb manure nutrients and nutrient recycling.