Bermudagrass Management in the Southern Piedmont USA: X. Coastal Productivity and Persistence in Response to Fertilization and Defoliation Regimes

Abstract

Productivity, quality, and persistence of ‘Coastal’ bermudagrass [Cynodon dactylon (L.) Pers.] pastures are affected by fertilization, but possible interactions with defoliation regime including animal grazing are not fully known. We evaluated three sources of fertilization with equivalent N rates [inorganic, crimson clover (Trifolium incarnatum L.) cover crop plus inorganic, and chicken (Gallus gallus) broiler litter] factorially arranged with four defoliation regimes [unharvested, cattle (Bos taurus) grazing to maintain high (4.5 ± 1.6 Mg ha−1) and low (2.5 ± 1.1 Mg ha−1) forage mass, and hayed monthly] on estimated forage dry matter production, forage and surface residue C/N ratio, and ground cover of pastures on a Typic Kanhapludult in Georgia during 5 yr. Mean annual forage dry matter production was 7.5 ± 0.7 Mg ha−1 with hay harvest but declined (1.3 Mg ha−1 yr−1) significantly with time as a result of lower precipitation. With grazing, estimated production was 8.3 ± 1.0 Mg ha−1 and did not change with time, suggesting that grazing cattle sustained forage productivity by recycling nutrients and creating better surface soil conditions. Coastal bermudagrass as a percentage of ground cover (initially 81%) declined 5 ± 2% yr−1 with unharvested and grazing to maintain low forage mass, declined 3 ± 1% yr−1 with haying, and remained unchanged (−1 ± 1% yr−1) with grazing to maintain high forage mass. Pastures with high forage mass were more productive than with low forage mass (9.2 ± 1.6 vs. 7.5 ± 1.1 Mg ha−1) from a forage sustainability perspective, primarily by avoiding encroachment of undesirable plant species.