Capabilities of Four Novel Warm-Season Legumes in the Southern Great Plains: Biomass and Forage Quality

Grain (pulse) legumes could provide high nitrogen (N), late summer forage for stocker cattle in the southern Great Plains (SGP). This study evaluated the forage yield and nutritive value of tropical annual legumes that were relatively uncommon in the SGP, at a site (35°40' N, 98°00' W) in central Oklahoma. Included were cultivars of pigeon pea ([Cajanus cajan (L.) Millsp.], cv. GA-2), guar ([Cyamopsis tetragonoloba (L.) Taub.], cv. Kinman), cowpea ([Vigna unguiculata (L). Walp.], cv. Chinese red), and mung bean ([Vigna radiata (L.) Wilcz.], cv. Berkins), and grain soybean ([Glycine max (L.) Merr.] cv. Hutcheson) was used as a control. Seeds were inoculated and planted (60-cm row spacing at 10 seeds m–1 row length) annually in mid-June 2003 through 2006. Aboveground samples were collected on six dates, from 45 to 120 d since planting. Soybean, pigeon pea, and guar averaged 3560, 3439, and 3321 kg ha−1, while mung bean and cowpea averaged 2918 and 2405 kg ha−1, respectively. Mung bean and cowpea accumulated the least N (70 and 65 kg N ha−1), while soybean, guar, and pigeon pea yielded 100, 93, and 77 kg N ha−1, respectively. Digestibility of cowpea, mung bean, soybean, and guar were similar (757 to 825 g kg−1), while pigeon pea was least digestible (634 g kg−1). These pulse legumes could provide producers in the SGP with options other than soybean for generating forage or biological N. S.C. Rao and B.K. Northup, USDA-ARS, Grazinglands Research Lab., 7207 W. Cheyenne St., El Reno, OK 73036. Received 22 Aug. 2008. *Corresponding author ([email protected]). Abbreviations: DSP, days since planting; MG, maturity group; N, nitrogen; IVDDM, in vitro digestible dry matter; SGP, southern Great Plains. Published in Crop Sci. 49:1096–1102 (2009). doi: 10.2135/cropsci2008.08.0499 © Crop Science Society of America 677 S. Segoe 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.