Monday, November 13, 2006
65-6

Harvesting Annual Ryegrass to Remove Excess Soil Nutrients in a Bermudagrass Pasture Fertilized with Broiler Litter.

John Read, P.O. Box 5367, USDA-ARS-NPA-SPNRU, USDA-ARS, Crop Science Research Lab, 810 Hwy 12 E, Mississippi State, MS 39762-5367, Karamat Sistani, USDA-ARS, 230 Bennett Lane, Bowling Green, KY 42104, Geoffrey Brink, US Dairy Forage Research Center, 1925 Linden Dr West, 1925 Linden Dr West, Madison, WI 53706-1108, United States of America, and Larry Oldham, Mississippi State University, Mississippi State, MS 39762.

Over the past several years, environmental policy related to animal agriculture has focused on land application of manure, especially how to stop or reverse soil phosphorus (P) build up and runoff. Overseeding bermudagrass with annual ryegrass appears to be an effective strategy for removing excess soil P in pastures fertilized with broiler litter. Hybrid bermudagrass may remove about 50-60 kg P ha-1 yr-1, depending on dry matter production, which can be affected by manure rate and soil type. Harvesting annual ryegrass can remove large amounts of P from soil, but few studies have determined its effects on manure soil nutrient concentration. The present study utilized small plots (4x6 m) of existing sod of ‘Coastal’ bermudagrass on a Ruston fine sandy loam with no history of litter application. A fertilizer study was conducted from 1999 to 2001 using single applications of 0, 4.5, 9, 18, and 36 Mg ha-1 litter in spring each year. In fall 2001, 2002, and 2003, half of each plot (2x6 m) was sown to ‘Marshall’ annual ryegrass. The plots were subsequently fertilized with 67 kg ha-1 N only following each harvest. Forage yield and P uptake increased linearly as litter rate increased, and values in 2002 and 2004 were significantly greater in bermudagrass-annual ryegrass than the bermudagrass system. Based on analysis of linear regression coefficients across litter rates, the two systems did not differ in the rate of drawdown in plant available P, total P or water P in surface soil (0-15 cm). Results suggest the environmental benefit of harvesting annual ryegrass was affected by precipitation, and was related more to the removal of manure P in the harvested hay than to a decrease in soil P concentration.

Handout (.pdf format, 713.0 kb)