Candidate Cool‐Season Legumes for Filling Forage Deficit Periods in the Southern Great Plains

Abstract

This study was conducted to determine seasonal forage production and nutritive value of the cool‐season annual legumes grasspea (Lathyrus sativus L. cv. AC‐Greenfix) and lentil (Lens culinaris Med. cv. Indianhead) grown to fill the spring forage deficit period of the southern Great Plains. Data were collected from March to June in 2001 through 2003 at the USDA‐ARS Grazinglands Research Laboratory, El Reno, OK. Seeds of each species was inoculated and planted (60‐cm row spacing) annually on 15 March (75 kg ha−1 for grasspea; 25 kg ha−1 for lentil) in 60‐m−2 plots. Aboveground biomass was collected on five dates [45–95 d after seeding (DAS)], dried 60 h at 60 to 65°C, weighed, and used to calculate aboveground standing crop. Samples were ground (1.0 mm) and analyzed for nitrogen (N) and in vitro digestible dry matter (IVDDM) concentrations. Standing crop and N concentration showed significant (P = 0.05) interactions between DAS, cultivars and years. Differences were detected for DAS × cultivar and DAS × year interactions for IVDDM concentration (P = 0.05). Grasspea outperformed lentil and reached its maximum yield of 6415 vs. 2013 kg ha−1, respectively, on 75 DAS before declining. Nitrogen concentration (23–55 g kg−1) and IVDDM (786 ± 3 g kg−1) of the two cultivars were similar during the growing season. The higher level of production gives grasspea greater potential as a component of wheat‐based (Triticum aestivum L.) forage systems in the southern Great Plains, particularly for filling the deficit period during late spring.