Effect of Winter Cover Cropping On Soil Nutrient Accumulation in Sorghum-Sudan Grass Fertilized with Broiler Litter in Western Kentucky.

Effect of winter cover cropping on soil nutrient accumulation in sorghum-sudan grass fertilized with broiler litter in Western Kentucky.

A. Netthisinghe, R.A.Gilfillen, W.T.Willian, and N.S.Rowland

Department of Agriculture, Western Kentucky University,

1906 College Heights Blvd. #41066, Bowling Green, KY 42101-10666 College Heights Blvd. #41066, Bowling Green, KY 42101-1066

Recent expansion of the poultry industry in Kentucky has lead to increased poultry litter production and concerns of proper disposal. Poultry litter is a good source of plant nutrients and have the ability to improve soil quality. Unless properly managed, long-term land application of poultry litter can cause soil nutrient accumulation and result in environmental problems of ground water pollution and surface water contamination.

Sorghum-sudan grass is a well-adapted warm season forage crop in Kentucky. It responds well to nitrogen fertility, produces high biomass and fits well for the nutrient management hay systems. A winter cover crop planted after the sorghum-sudan grass fertilized with poultry litter can continue to extract the soil nutrients, and to slow down the rate of soil nutrient accumulation. This study investigates the soil nutrient accumulation with sorghum-sudan grass cultivated under four different fertilizer treatments; poultry litter applied at recommended N rate, recommended P rate, recommended P rate with supplemental N rate, and inorganic fertilizer with a cover crop rye grass and fallow in winter. Initial analysis of three-year end data indicates that poultry litter applied at recommended N rate tends to accumulate P, K, Mg, S, Cu, Zn and Na heavily in soil. Data also show  slow accumulation of the same elements in recommended N rate treatment with the cover crop. These results suggest that incorporation of winter cover crops can enhance the suitability of poultry litter as a soil nutrient supplement while reducing the potential environmental impacts.