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Bermudagrass Response to High Nitrogen Rates, Source, and Season of Application
Author(s) -
Osborne Shan L.,
Raun William R.,
Johnson Gordon V.,
Rogers Jerry L.,
Altom Wadell
Publication year - 1999
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1999.00021962009100030013x
Subject(s) - loam , forage , fertilizer , cynodon dactylon , agronomy , urea , udic moisture regime , nitrogen , zoology , growing season , environmental science , chemistry , biology , soil water , organic chemistry , soil science
High N rates and source of N have been thoroughly evaluated in bermudagrass [ Cynodon dactylon (L.) Pers.] forage production, but less is known concerning season of application and estimated fertilizer N recovery in these systems. Two field studies (Ardmore, OK: Wilson silt loam, Vertic Haplustalfs; Burneyville, OK: Minco fine sandy loam, Udic Haplustolls) were conducted at two locations over two years to evaluate the effects of rate, timing, and source of N on bermudagrass forage yield, total N, NO 3 concentration, and estimated fertilizer N recovery. Nitrogen was applied at rates of 112, 224, 448, 672, and 1344 kg N ha −1 as NH 4 NO 3 or urea in early spring (March) and late summer (August). Fertilizer N recovery can be maximized at rates of 112 and 224 kg N ha −1 applied in the early spring and late summer, respectively. Even when N rates of 1344 kg N ha −1 were applied annually, bermudagrass forage NO 3 ‐N was seldom above 2000 mg kg −1 , which is below published toxic levels (2400–4500 mg kg −1 ) for cattle ( Bos taurus ) consumption. Early‐spring applied N increased yields, N removal, and fertilizer recovery compared with late‐summer applied N. Fertilizer N recovery was higher for NH 4 NO 3 than for urea, especially when applied in late summer. Late‐summer applications of urea should be avoided, due to increased NH 3 volatilization losses. Nitrogen applied at 112 kg N ha −1 in early spring can result in fertilizer recoveries in excess of 85%. These high recoveries in forage production systems are possibly a result of continuous preanthesis forage harvesting when gaseous plant N losses are small, but which increase following anthesis.