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

The second occurs in late spring and early summer (May to June) when wheat has ceased growth and warm-seaThis study was conducted to determine seasonal forage production son pastures are not yet available for grazing (Northup, and nutritive value of the cool-season annual legumes grasspea (Lath2003). New plant species that can fill these gaps with yrus sativus L. cv. AC-Greenfix) and lentil (Lens culinaris Med. cv. Indianhead) grown to fill the spring forage deficit period of the southdependable high quality forage are needed to support ern Great Plains. Data were collected from March to June in 2001 sustainable forage-livestock production systems in the through 2003 at the USDA-ARS Grazinglands Research Laboratory, region. El Reno, OK. Seeds of each species was inoculated and planted (60-cm Recent research in the northern Great Plains has forow spacing) annually on 15 March (75 kg ha 1 for grasspea; 25 kg cused on partially replacing summer fallow with annual ha 1 for lentil) in 60-m 2 plots. Aboveground biomass was collected legumes for ground cover, green manure, or forage on five dates [45–95 d after seeding (DAS)], dried 60 h at 60 to 65 C, (Badaruddin and Meyer, 1989a, 1989b; Biederbeck et weighed, and used to calculate aboveground standing crop. Samples al., 1993). Little research has been conducted on potenwere ground (1.0 mm) and analyzed for nitrogen (N) and in vitro tial candidates for green manure or grazing in the southdigestible dry matter (IVDDM) concentrations. Standing crop and N ern Great Plains. Among the grain legumes, grasspea, concentration showed significant (P 0.05) interactions between DAS, cultivars and years. Differences were detected for DAS also known as chickling vetch, and lentil have been cultivar and DAS year interactions for IVDDM concentration (P noted for their tolerance to dry conditions and adapt0.05). Grasspea outperformed lentil and reached its maximum yield ability to difficult environments (Nygaard and Hawtin, of 6415 vs. 2013 kg ha 1, respectively, on 75 DAS before declining. 1981; Biederbeck et al., 1993; Campbell, 1997). Nitrogen concentration (23–55 g kg 1) and IVDDM (786 3 g kg 1) Grasspea is a grain legume grown on the Indian subof the two cultivars were similar during the growing season. The higher continent, southern Europe, and northern Africa for level of production gives grasspea greater potential as a component of forage and grain production for both livestock and huwheat-based (Triticum aestivum L.) forage systems in the southern man consumption (Chowdhury, 1988). This crop has Great Plains, particularly for filling the deficit period during late significant potential for the southern Great Plains bespring. cause of its tolerance to stress (Palmer et al., 1989). Despite a high level of drought tolerance, it is not greatly affected by excessive rainfall and can be grown on floodT primary goals of grazing-based forage systems prone land (Kaul et al., 1986; Rathod, 1989). Grasspea are to provide year-round high-quality forage and is well adapted to cool-season production in warm-temreduce the use of expensive stored forage or purchased perate and subtropical areas such as Africa and western feeds. In the southern Great Plains, winter wheat and Asia. It is widely grown in these regions for its high such warm-season perennial grasses as bermudagrass yield potential and high-quality forage, as an alternative (Cynodon dactylon L.), and Old World bluestem (Bothrito fallow periods in cropping systems (Osman and Nerochloa spp.), are the primary forage resources for livesoyan, 1986). Gowda and Kaul (1982) reported forage stock production (Phillips and Coleman, 1995: Coleman yields of 7 to 10 Mg ha 1 in Bangladesh when inand Forbes, 1998; Krenzer, 2000). Wheat pasture is availterseeded with maize (Zea mays L). able for grazing from November to mid March if a grain Over the past decade, this species has received incrop is harvested, or through late April to early May if creased attention as a multi-use crop in arid regions grain is not harvested (Redmon et al., 1995; Krenzer, of the northern Great Plains (Biederbeck et al., 1993; 2000). The warm-season grasses are available for grazing Biederbeck and Bouman, 1994). In parts of this region, from June through September, although quality is limgrasspea yields of 5000 kg ha 1 with 30% crude protein ited during the last two months. Therefore, the standard have been reported (Raloff, 2000). However, more exgrazing system used in the southern Great Plains has tensive use of this grain has been limited by presence voids during two critical times of the year. One occurs of the neurotoxin -N-oxalyl-l, -diaminopropionic in the fall (September to November), when quality and acid (ODAP) in older accessions. There have been no production of the warm-season perennial grasses are reported cases of Lathyrism in ruminant species, as some low and winter wheat is not yet available for grazing. groups of microbes in the foregut utilize the amino acid components of the neurotoxin (Rasmussen et al., 1992). USDA-ARS, Grazinglands Research Lab., 7207 W. Cheyenne St., Plant breeders have concentrated on developing lowEl Reno, OK 73036. Received 7 Jan. 2005. *Corresponding author ODAP cultivars and the variety ‘AC-Greenfix’ was re([email protected]). leased by the Semi-Arid Agricultural Research Center Published in Crop Sci. 45:2068–2074 (2005). at Swift Current, SK, Canada. Forage and Grazing Lands Lentil is an important crop in the rainfed farming sysdoi:10.2135/cropsci2005.0019 tems of the Mediterranean-like environments of western © Crop Science Society of America 677 S. Segoe Rd., Madison, WI 53711 USA Asia and northern Africa. The grain is a valuable source 2068 Published online August 26, 2005