Wednesday, November 7, 2007
271-5

Forage Cutting Height and Interval: Relationship to Phosphorus Uptake by Bermudagrass Fertilized with Broiler Litter.

John Read1, Dennis Rowe2, and David Lang2. (1) P.O. Box 5367, USDA-ARS, Crop Science Research Lab, 810 Hwy 12 E, Mississippi State, MS 39762-5367, (2) Experimental Statistics, Mississippi State University, Mississippi State, MS 39762-5367

Broiler litter applied to meet bermudagrass N requirement contains more P than required by the plant. Maximizing nutrient uptake would facilitate P removal from bermudagrass hay fields and reduce build-up of soil P. High soil P increases the potential for P transport by runoff or leaching that may cause eutrophication. This study determined if stage of growth and the distribution of forage yield affect P uptake in hybrid Tifton 44 bermudagrass. Litter was hand-applied at 4.5 Mg ha-1 in March and May, and 67 kg ha-1 N (34-0-0) was applied in late May. Harvests began in mid-June. Averaged across 2004 and 2005, forage biomass increased significantly as harvest interval increased from 35 to 49 d. In the 49-d treatment, decreasing the cutting height from 9 to 3 cm increased forage yield by about 2.7 Mg ha-1. A much smaller increase of about 1.5 Mg ha-1 due to decreased cutting height was evident in plants harvested at 21 and 35 day intervals. Trends in annual P uptake closely followed those observed for biomass yield. Results provide information to forage producers on a straight forward method to enhance the recovery of nutrients applied in broiler litter to bermudagrass hay fields.