Submitted to: American Society of Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2004
Publication Date: November 1, 2004
Citation: Read, J.J., Sistani, K.R., Brink, G.E., Rowe, D.E. 2004. Forage yield and plant reflectance in annual ryegrass fertilized with poultry litter [abstract]. Agronomy Abstracts. 2004 CDROM.
Winter annual forages can assimilate large amounts of phosphorus (P) from soils fertilized with poultry litter. Because changes in multispectral reflectance of plant canopies are indicative of the amount and vigor of green vegetation, such measurements may assist in harvest timing of annual ryegrass (Lolium multiforum Lam.). Our objectives were to determine the effects of poultry litter on forage yield and P uptake, and seasonal changes in normalized difference vegetation index (NDVI). Annual ryegrass was overseeded in bermudagrass plots that in the previous three years had received 0, 4.5, 9, 18, and 36 Mg per ha poultry litter. Plots were subsequently fertilized in summer with inorganic nitrogen fertilizer, ammonium nitrate. Harvest data from Spring 2002, 2003 and 2004 indicated forage yield and P uptake were greater at Mize a location with 20+ years of litter than at Newton, a location with only 3 years of litter. At both locations and in most years, the 36 and 18 Mg per ha rates had significantly greater P uptake and NDVI than the 0 and 4.5 Mg per ha rates. Yield, P uptake, and NDVI differed in a manner consistent with antecedent rates of poultry litter. Treatment differences in NDVI were significant on each sampling date at Newton. Temporal changes in NDVI during spring 2004 support evidence that mid April is when yield, and hence nutrient uptake, is maximal in annual ryegrass.