Bermudagrass Management in the Southern Piedmont USA

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Abstract
Fate of applied N in forage-based agricultural systems is important to long-term production and environmental impacts. We evaluated the factorial combination of N fertilization targeted to supply 20 g N m−2 yr−1 and harvest strategies on soil-profile inorganic N during the first 5 yr of ‘Coastal’ bermudagrass [Cynodon dactylon (L.) Pers.] management. Harvest strategy had much larger effects than fertilization strategy, most notably that soil-profile inorganic N was lower when hayed than under other systems. In the upper rooting zone (0- to 0.3-m depth), soil inorganic N (initially at 3.1 g m−2) remained unchanged during the 5 yr under unharvested and low and high grazing pressures (0.00 ± 0.08 g m−2 yr−1), but declined with haying (−0.25 g m−2 yr−1). In the lower rooting zone (0.3- to 0.9-m depth), soil inorganic N (initially at 2.9 g m−2) accumulated with unharvested and low and high grazing pressure (0.64 ± 0.20 g m−2 yr−1), but remained unchanged with haying (−0.06 g m−2 yr−1). Below the rooting zone (0.9- to 1.5-m depth), soil inorganic N (initially at 5.8 g m−2) increased with unharvested and high grazing pressure (0.34 ± 0.03 g m−2 yr−1), was unchanged with low grazing pressure (−0.10 g m−2 yr−1), and declined with haying (−0.50 g m−2 yr−1). Applied N appears to have been efficiently utilized by forage with subsequent sequestration into soil organic matter and little movement of inorganic N below the rooting zone (<2% of applied N), irrespective of inorganic or organic fertilization strategy designed to supply sufficient N for high animal production from grazing. Copyright © 2003. American Society of Agronomy, Crop Science Society of America, Soil Science Society . Published in J. Environ. Qual.32:1316–1322.