Fresh versus field-cured grass quality, mineral, and nitrate concentration at different nitrogen rates. (Forage & Glazing Lands)

Determining the extent of change in fresh versus field-cured grass hay quality, mineral, and N[O.sub.3]-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 N[O.sub.-3]-N concentrations of orchardgrass (Dactylis glomerata L.), smooth bromegrass (Bromus inermis Leyss.), and timothy (Phleum pratense 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.sup.-1]) and Ca (4.3 vs. 6.2 g [kg.sup.-1]) concentrations were greater in field-cured compared with fresh forage in 1999 across N rates. Tissue N[O.sub.-3]-N concentration was greater in field-cured orchardgrass at all N rates and at the Iow 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 N[O.sub.-3]-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.
COOL-SEASON GRASSES are commonly grown in the northeast USA for hay production because of their tolerance of poor drainage, lower establishment and maintenance costs, and faster drying rates than legumes. [...]