Expected Economic Potential of Substituting Legumes for Nitrogen in Bermudagrass Pastures.

Grazing warm-season grass pastures with stocker cattle {Bos taurus) is an important economic activity in the southern Great Plains, and substantial increases in the price of Ν fertilizer have negatively affected profitability of forage producers. The goal of the study was to determine if bermudagrass [Cynodon dactylon (L.) Pers.] pastures interseeded with either annual or perennial legumes are more profitable than the conventional method of fertilizing with 112 kg Ν ha-1 commercial fertilizer. A completely randomized design grazing study was conducted in south-central Oklahoma during the spring and summer months of 2008, 2009, and 2010. Preconditioned stocker cattle (260 ± 47 kg head-1) were randomly assigned to pastures (1.42 ± 0.10 ha; three replicates per system) at 2.32 ± 0.40 animals ha-1, beginning when measured standing forage reached 2000 kg ha-1 and grazing continuously until forage mass declined to 1000 kg ha-1. Results of the 3-yr grazing study show that under continuous stocking for the growing conditions common to the south-central Great Plains, the legume systems could not compete economically with the common practice of fertilizing bermudagrass pastures with synthetic inorganic Ν fertilizer. Results are most sensitive to number of grazing days, price of N, and prices of legume seed. [ABSTRACT FROM AUTHOR]