Impact of poultry litter rates on annual ryegrass production

Marcus M. Eichhorn Jr.,

Poultry litter manure is a renewable fertilizer resource that contains all the plant nutrients required for plant growth and reproduction. In north Louisiana, more than 59,000 tons of poultry litter are generated annually by flocks in broiler houses. Nearly all of this manure is surface applied on pastures and hay meadows. Runoff water from these pastures may be a significant carrier of pollutants that impair the designated use of area water bodies. Soil-incorporation of manure reduces the runoff pollution potential.

The majority of livestock producers in north Louisiana annually plant about 30,000 acres in annual ryegrass for grazing livestock and producing baleage, silage and hay. Nearly all producers apply commercial inorganic fertilizers to these acres, the cost of which increases almost yearly.

Results of a fertility experiment conducted over the past two years at the LSU Agricultural Center’s Hill Farm Research Station showed that yield of annual ryegrass, managed for pasture production, optimized annually at 7,200 pounds of dry forage per acre where 4 tons per acre of stacked broiler litter was broadcast on the surface of a prepared seedbed and soilincorporated at 0- to 6-inch soil depth before planting annual ryegrass.
Use of the stacked broiler litter was 3.7 times more cost effective than commercial fertilizer for annual ryegrass production where both fertilizer sources were soil-incorporated at the same rates of nitrogen, phosphate, potash and sulfur. Cost of the broiler litter was $44 per acre per year. Cost for commercial fertilizer was $162.70 per acre per year. Annual ryegrass yield with the commercial fertilizer was 7,100 pounds of dry matter per acre, which was similar to that of stacked broiler litter.

Results of the study also indicated no appreciable buildup of phosphorus where the soil was cropped with annual ryegrass in the presence of either the 4-ton broiler litter or commercial fertilizer equivalent per acre rate. Therefore, these data indicated that runoff or ground waters from fields managed similarly for annual ryegrass production would have minimal potential impact on phosphorus pollution of adjacent water bodies.

Marcus M. Eichhorn Jr., Professor, Hill Farm Research Station, Homer, La.

(This article was published in the spring 1999 issue of Louisiana Agriculture.)

8/19/2009 7:31:38 PM
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