Broiler Litter vs. Ammonium Nitrate as Nitrogen Source for Bermudagrass Hay Production: Yield, Nutritive Value, and Nitrate Leaching

Abstract

ABSTRACTThe Lower Suwannee River Basin (LSRB) in northern Florida is environmentally sensitive. This study evaluated two surface‐applied N sources for ‘Tifton 85’ bermudagrass (Cynodon spp.) hay production and associated risk of nitrate contamination of groundwater. The study was conducted at two locations in the LSRB where soils are deep, sandy Entisols. During a 2.5‐yr period, bermudagrass received sole N source ammonium nitrate (AN), applied at 42, 84, 126, and 168 kg N ha−1 per growth interval, or sole N source broiler (chicken, Gallus gallus domesticus) litter (BL), applied at 84 and 126 kg N ha−1 Plots were arranged using a randomized block design with three or four replications depending on the location. Suction‐cup lysimeters were installed at a 1.4‐m soil depth to monitor nitrate movement from the primary rooting zone. For AN, dry matter yield and crude protein (CP) concentration increased with an increase in N level, while forage P declined and in vitro digestible organic matter increased. Forage yield with BL was 64, 48, and 67% of yield with AN applied at common levels in 1998, 1999, and 2000, respectively. Forage CP was mostly less for BL than for AN, but forage P was greater for BL. A potential risk to groundwater quality due to nitrate leaching below the primary rooting zone was observed only with AN applied at 168 kg N ha−1 Probable ammonia emissions from surface‐applied BL, however, likely resulted in poorer bermudagrass production and could impact nearby surface waters.