Expected Economic Potential of SubstitutingLegumes 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 N fertilizer have negatively affected profi tability 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 profi table than the conventional method of fertilizing with 112 kg N 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 N fertilizer. Results are most sensitive to number of grazing days, price of N, and prices of legume seed. J.T. Biermacher, R. Reuter, M.K. Kering, J.K. Rogers, J. Blanton, Jr., and T.J. Butler, The Samuel Roberts Noble Foundation, Inc., Ardmore, OK 73401; J.A. Guretzky, Dep. of Horticulture and Agronomy, Univ. of Nebraska, Lincoln, NE 68583-0915. Received 25 Aug. 2011. *Corresponding author ( [email protected]). Abbreviations: ADF, acid detergent fi ber; BG-A, bermudagrass interseeded with alfalfa; BG-CV, bermudagrass interseeded with clover and vetch; BG-N, bermudagrass plus 112 kg N ha–1 from urea; CP, crude protein; IVDMD, in vitro dry matter digestibility; LR, likelihood ratio; NDF, neutral detergent fi ber; NIRS, near-infrared refl ectance spectroscopy; PLS, pure live seed. Published in Crop Sci. 52:1923–1930 (2012). doi: 10.2135/cropsci2011.08.0455 Freely available through the author-supported open-access option. © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.