Monday, November 13, 2006

Residual Nutrient Removal by Winter Cover Crop From Broiler Litter Amended Soils.

Jennifer Johnson, B.B. Sleugh, R.A. Gilfillen, W.T. Willian, and M. Futrell. Western Kentucky University, 1906 College Heights Blvd. #41066, Bowling Green, KY 42101-1066, United States of America

Cover crop use to extract excess soil nutrients that remain after fertilizing an annual crop with  broiler litter has not been fully explored.  This study’s objective was to assess total nutrient removal by sorghum sudangrass (Sorghum bicolor (L.) Moench) followed by a rye (Secale cereale L.) cover crop compared to single crop of sorghum sudangrass as a tool for preventing excessive soil nutrient accumulation.  A randomized complete block experiment with four replications and four treatments; litter applied at recommended nitrogen [Litter–N] rate; at the recommended P rate with commercial nitrogen  [Litter–P+N]; recommended P rate [Litter-P]; and INORGanic fertilizer [INORG] was established in 2005.  Sorghum sudangrass was seeded in the spring and rye planted after the last harvest of the season.  Forage acid detergent fiber (ADF), neutral detergent fiber (NDF), crude protein (CP), P, Cu, Fe, and Zn were determined.  Treatment did not significantly affect  rye NDF, Cu, P, or Fe.  ADF concentrations were highest for Litter-P plots and Litter-P+N and Litter-P resulted in higher ADF than Litter-N.  Crude protein was greatest in Litter-N plots and INORG plots, and lowest in Litter-P plots.  Zn was higher in the Litter-N plots and lowest in Litter-P plots.  The use of Inorganic fertilizer or lower rates of broiler litter based on P requirements and supplemented with Inorganic N are best when determining overall forage nutritive values and removal.