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Fresh versus Field-Cured Grass Quality, Mineral, and Nitrate Concentration at Different Nitrogen Rates

Singer, Jeremy W.
Crop science 2002 v.42 no.5 pp. 1656
Dactylis glomerata, Bromus inermis, mineral content, nitrogen content, nitrogen, nutrient availability, nitrate nitrogen, crude protein, application rate, dietary fiber, ammonium nitrate, New Jersey
Determining the extent of change in fresh versus field-cured grass hay quality, mineral, and NO-N concentrations under rain-free conditions provides valuable information to hay producers. The objectives of this research were to evaluate the effect of fresh vs. field-cured forage on crude protein (CP), neutral detergent fiber (NDF), total digestible nutrients (TDN), P, K, Ca, and NO-N concentrations of orchardgrass (L.), smooth bromegrass (Leyss.), and timothy (L.), and to determine if interactions with N rate exist. At the low N rate in 1999 and 2000, orchardgrass CP in fresh and field-cured forage, NDF, and TDN concentrations were different. Orchardgrass P and K concentrations were lower in field-cured compared with fresh forage, but differences were inconsistent across N rates. In contrast, smooth bromegrass K (23 vs. 27 g kg) and Ca (4.3 vs. 6.2 g kg) concentrations were greater in field-cured compared with fresh forage in 1999 across N rates. Tissue NO-N concentration was greater in field-cured orchardgrass at all N rates and at the low N rate in smooth bromegrass in 1999. Interactions between N rate and fresh vs. field-cured smooth bromegrass were detected for all variables in 1999 and orchardgrass K concentration in 2000. These results demonstrate that changes in grass quality, mineral, and tissue NO-N concentrations occur under rain-free field curing conditions. Consequently, forage scientists conducting research on grass hay quality indices and mineral content should sample subsequent to field-curing to provide accurate results.