Srinivas Rao, B. K. Northup, W. A. Phillips, and H. S. Mayeux. USDA-ARS, 7207 W. Cheyenne St., 7207 W Cheyenne St., El Reno, OK 73036-2144
Nitrogen fertilizers are essential to maximize productivity of monocultures of perennial grasses. Including legumes in such pastures can improve seasonal distribution of high quality forage, and reduce N fertilizer requirements. This study determined if incorporation of annual cool-season legumes could lengthen the spring forage production period of bermudagrass (Cynodon dactylon) pastures. Treatments applied to experimental plots included inter-seeding of grasspea (Lathyrus sativa L. cv. AC-Greenfix) or lentil (Lens culinaris Med. cv. Indianhead) in mid-March with 60 kg ha-1 P205, or application of 0, 45, or 90 kg ha-1 N. Forage samples were clipped from random (n=3) 0.25 m-2 quadrates on five sampling dates (May 1 to July 15) annually during 2001-2003, and used to define total biomass and concentrations of nitrogen (N) and in vitro digestible dry matter (IVDDM). Significant (P<0.05) 2-way interactions were noted between sampling date, years and treatments for total biomass, as were 3-way interactions for N and IVDDM. End-of-season biomass of plots inter-seeded with grasspea (5550 kg ha-1) was intermediate to biomass of plots receiving 45 or 90 kg ha-1 N (5305 and 7785 kg ha-1, respectively). Average forage N and IVDDM concentrations of the bermudagrass-grasspea mixture were 34 and 6% higher, respectively, than bermudagrass treated with 90 kg ha-1 N. End-of-season biomass of the lentil treatment was similar to unfertilized controls, but N and IVDDM concentrations were intermediate to 45 and 90 kg ha-1 N treatments. Inter-seeding grasspea into bermudagrass pasture can produce sufficient forage in spring to allow the start of grazing one month earlier, and improve forage quality through mid-summer.
Handout (.pdf format, 3966.0 kb)
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