Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/12/2006
Publication Date: 11/16/2006
Citation: Read, J.J., Sistani, K.R., Brink, G.E., Oldham, J.L. 2006. Harvesting annual ryegrass to remove excess soil nutrients in a bermudagrass pasture fertilized with broiler litter [abstract]. Agronomy Abstracts. Paper 65-6, CD-ROM. Interpretive Summary: None required.
Technical Abstract: Forage producers in the southeast USA often overseed bermudagrass with annual ryegrass in order to enhance annual dry matter (DM) production. As a result, this practice has potential to increase the removal rate of excess phosphorus (P) from manure-impacted soils. This research compared the fate of broiler litter P and other manure nutrients in ryegrass-bermudagrass and bermudagrass winter fallow systems. Plots of ‘Coastal’ bermudagrass were established on Ruston fine sandy loam soil and fertilized for three years with 0, 4.5, 9, 18, and 36 Mg/ha litter. ‘Marshall’ annual ryegrass was planted to half of each plot (2x6 m) in fall 2001, 2002, and 2003. Annual DM yield and P uptake increased significantly as litter rate increased. Averaged across rates, P uptake was greater (P<0.001) in ryegrass-bermudagrass than bermudagrass in 2002 and 2004, but not in 2003 (P>0.70) when rainfall was above average. Analysis of surface soil, 0-15 cm, indicated a decrease in water-extractable P over time, but was inconsistent in changes of total P or plant available P (Mehlich-3 extractant). The effect of forage system and its interaction with litter rate was not significant for these forms of soil P. Soil P decreased the most over time in the 36 Mg/ha litter treatment due to increased soil fertility, DM yield, and nutrient uptake. Results indicate the environmental benefit of harvesting annual ryegrass was related more to the removal of manure P in the harvested hay than to a decrease in soil P concentration.