Is peanut a good choice as a cover crop in Hawaii?
Answer: Perennial peanuts (A. glabrata) are native to South America. This plant is different from its more well-known cousin A. hypogaea in that it’s most often propagated from its rhizomes, rather than by seed. It can cross with other closely related species like A. paraguariensis and A. kretschmeri, giving rise to sterile triploids that only form short rhizomes. Its creeping nature makes perennial peanut suitable as a forage crop and understory ground cover for tropical fruit and nut groves. Without competition it can spread six feet per year, but expect less than a sixth of that with grass competition. Thus, stand establishment is very important when using perennial peanut. Stand establishment is initiated by planting sprigs, much like planting Bermuda grass, and the same equipment can be used (Rouse et al., 2001).
A. glabrata is a multi-use legume. It fixes about 150 pounds of nitrogen per acre per year. It is palatable to livestock and has been shown to be beneficial in weight gain and/or milk production of various species. In addition to providing nitrates to fruit and nut trees and providing protein for livestock, it can also be cut and baled for hay and sold. In some cases, perennial peanuts are used for ornamental purposes due to their showy yellow flowers (Miavitz and Rouse, 2002).
Perennial peanuts prefer well-drained, sandy soils with a pH range from 4.5 to 8 and do not tolerate waterlogging. Generally, A. glabrata needs from 1,000 to 2,000mm (39 to 78 inches) of rainfall a year but can survive on 750mm (29 inches). One variety, Latitude 34, can survive on 450mm (18 inches) a year (Muir et al., 2010).
There is another perennial peanut that is used in Hawaii, A. pintoi (Seeded Perennial Peanut), which seems to be the more widely used species outside of the Continental United States. Most of the Australian literature is centered on the Amarillo variety, which is used in orchards there (Hensley et al., 1997). The two species are quite similar for the most part, but they react differently in different situations, like drought and cold. A. pintoi produces more seed than A. glabrata (Rhizomal Perennial Peanut), but neither of them produce very much in comparison to A. hypogaea (Gosper and Murray, 2003).
Learn more in the ATTRA publication Cover Crop Options for Hot and Humid Areas. This publication discusses the characteristics of cover crops that are better suited for areas with hot, humid summers, like the southern portions of Texas and Florida and along the Gulf Coast, the Caribbean, Hawaii, and points beyond with similar climatic conditions. It includes a table that will allow you to make the best decision for your situation about which cover crops may suit your individual needs. It also includes a general inoculant guide for legume crops.
Gosper, H., and G. Murray. 2003. Covercrops for subtropical orchards. Agfact H6.3.10. NSW Agriculture’s Horticulture Program.
Hensley, David, Julie Yogi, and Joseph DeFrank. 1997. Perennial Peanut Groundcover. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa, Honolulu, HI.
Miavitz, E., and R. Rouse. 2002. Rhizomal perennial peanut in the urban landscape. Proceedings of the Florida State Horticultural Society. Vol. 115. p. 136-138.
Muir, J.P., T.J. Butler, W.R. Ocumpaugh, and C.E. Simpson. 2010. ‘Latitude 34,’ a perennial peanut for cool, dry climates. Journal of Plant Registrations. Vol. 4. p. 106—108.
Rouse, R.E., R.M. Muchovej, and J.J. Mullahey. 2001. Guide to using perennial peanut as a cover crop in citrus. Florida Cooperative Extension Service Factsheet HS-805.