Morteza Mozaffari1, Nathan A. Slaton2, C. G. Herron1, and S. D. Carroll1. (1) PO Drawer 767, University of Arkansas Soil Testing and Research Laboratory, Marianna, AR 72360, (2) University of Arkansas, University of Arkansas, 1366 W. Altheimer Dr., Fayetteville, AR 72704
Pelleted poultry manure (PPL) is currently being marketed as a N fertilizer in Arkansas. There is virtually no information on nutrient availability from PPL in the region. A three-year field study was conducted in 2005-2007 on a representative soil to evaluate the immediate and residual availability of N from PPL and compare it with urea. In 2005, urea was applied at total-N rates of 50, 100, 150, 200, 250 and 300 lb N/acre and PPL was applied at total N rates of 80, 160, 240, 320, and 400 lb/acre. An unfertilized control (0 lb N/acre) was also included. The same rates of urea were applied to the same plots in succeeding years, but no additional PPL was applied. In 2005 corn grain yields significantly increased as inorganic-N and PPL-N rates increased to 250 and 320 lb N/acre respectively. In 2006 and 2007 applications of up to 300 lb N/acre from urea significantly increased corn grain yields. Grain yields in plots that received greater than 160 lbs of total-N/acre from PPL were significantly higher than control plots indicating that residual N from PPL (applied in 2005) was beneficial to corn. The data suggest that about one-half of the total N in PPL is plant available in the first year and significant but diminishing amounts will be available in succeeding years. The effect of urea and PPL on grain N uptake will be presented and the implications of the findings for agronomic and environmental management of PPL will be discussed.