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Sustainable Agriculture in Hawaii
Cover Crops: Legumes
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Perennial Peanut

Arachis pintoi

Perennial peanut is used as a ground cover and a cover crop
throughout the state under a wide range of conditions
Perennial peanut 'Golden Glory' in an organic fruit tree orchard on the north shore of O'ahu.
Perennial peanut 'Golden Glory' in an organic fruit tree orchard on the north shore of O'ahu.
Photo: Radovich
Perennial peanut 'Amarillo' in a landscape nursery on the Hamakua coast
Perennial peanut 'Amarillo' in a landscape nursery on the Hamakua coast.
Photo: DeFrank

Also known as: Pintoi Peanut, Amarillo Peanut

Benefits and Costs of Using Perennial Peanut as Living Mulch for Fruit Trees in Hawai‘i
(downloadable .pdf)

Summary
  • Tropical low growing (about 8 inches high), non-twining, nitrogen-fixing legume
  • Used as a cover crop in many perennial crops including mango, avocado, coffee, banana, oil palm, macadamia, cocoa, cassava, citrus, pineapples, plantains, dryland taro, and hearts of palm
  • Used as ground cover in Hawai`i landscapes
  • Used for intensively managed grass/legume pastures in South America (CIAT, Colombia)
  • Used for pasture legume in tree plantations
  • Takes about 6 months to become well established and requires weed control during that time. Once established it provides excellent weed control.
  • A. pintoi scored low (not currently recognized as invasive in Hawaii, and not likely to have major ecological or economic impacts on other Pacific Islands) based on the HP-WRA screening process.
  • Some shade tolerance reported
  • Tolerant of high Aluminum saturation. Some indications of tolerance to Manganese.

Common Name
Its common name is perennial peanut or pinto peanut (Hensley). According to Cook, the common name is pinto peanut or thua lisong tao (Thailand).

Scientific Name
The scientific name is Arachis pintoi Krap. & Greg., nom. nud. (Cook).

Cultivar
Two popular cultivars are ‘Golden Glory’ which is a popular landscape ground cover in Hawai`i and ‘Amarillo’ which was developed in Australia for forage and cover crop uses (Hensley). CIAT accessions are used primarily as pasture legumes. Several peanut cultivars are being grown at the Mealani Experiment station on the Big Island (Fukumoto and Yamasaki). There are numerous synonyms and some confusion over varietal names. (Cook et al.).

Seed Description
Seeds are light brown, 8-11 mm x 4-6 mm (Cook).

Seedling Description
Seedlings germinate in 7-10 days. With adequate resources, they grow rapidly and develop a deep tap root. Stolons of ‘CIAT 17434‘ seedlings begin to extend at 30 days after planting (Mitschele).

Mature Plant Description
Perennial or pinto peanut species and cultivars are low growing,  about 8 inches (20 cm) high, non-twining, nitrogen-fixing legumes. The plants have four oval leaflets on each petiole and light to dark yellow, pea-like flowers. Varieties can differ slightly in leaf size, shape and color. The seed is an underground nut, one per pod, which is not edible. Plants flower year round (Hensley). Stems grow along the ground and root at the nodes (Glover).

Perennial peanut seedling

Temperature
Perennial peanut is adapted to the tropics (Cook).

Origin and Geographic Range
Perennial peanut originates from central Brazil (collected from the mouth of the Jequitinhonha River). It has since been distributed to Argentina, Australia, Colombia, the United States, and more recently to South East Asia, Central America and the Pacific (Cook).

Ecology
Central Brazil’s climate is humid tropical, with rainfalls ranging from 1800-2000 mm (70-80 in) from October to May and 200 mm (8 inches) from June to September. Perennial peanut grows naturally in red sandy-loam alluviums under low forest with a fairly dense canopy (Cook).

Water
Perennial peanut grows best in areas receiving an annual rainfall of 40 inches (1000 mm) or more. It can withstand 3-4 months of drought, but will shed many of its leaves (Glover). It is adapted to low areas (with sandy loam soils) that are wet to flooded in the wet season. It will not persist on waterlogged, poorly structured clays (Cook). Irrigation is especially critical if cuttings are being used for establishment.

Nutrients
Perennial peanut originates from central Brazil and is adapted to that region. It tolerates soils with low fertility (it is a legume and fixes its own nitrogen). It tolerates soils with 70% or greater Al saturation. It performs best with >3% organic matter in the soil (Glover). In pot experiments it has shown a tolerance to Mn (Cook).

Soil pH
Although naturally adapted to areas of lower pH, under cultivation it can adapt to pH ranges from low to neutral (Cook). Whitening or chlorosis of new growth may occur at alkaline pH (Hensley et al.)

Soil Type
Perennial peanut's native habitat is in red, sandy loam alluviums, seasonally wet to flooded. Under cultivation it has proven adaptable to soils ranging from sand to clay texture. It will not persist on seasonally waterlogged, poorly structured clays (Cook). In a greenhouse study in Hawaii, seedlings of ‘CIAT 17434‘ grew better in a relatively fertile mollisol (Waialua series) than a weathered oxisol (Wahiawa series) when plants were not inoculated or fertilized. However, this difference in growth was not observed when seeds were inoculated with cowpea strain rhizobia (Mitschele).

Shade Tolerance
Perennial peanut reportedly grows well under heavy (70-80%) shade (Glover). However, this contradicts observations on several orchards in Hawaii that peanut biomass decreases as tree canopies close.

Salinity Tolerance
Perennial peanut has a low tolerance for salinity (Cook).

Herbicide Sensitivity
The herbicides Dual® , Balan Granular® , Treflan Granules® , Snapshot Granular® , Fusilade II® , and Vantage® are reported not harmful to pinto peanut at recommended label rates. Ronstarä can yellow the leaves and kill the plant (Hensley).

Life Cycle
Seedlings develop quickly with good growing conditions when planted at a rate of several plants per square meter. Complete ground cover can be reached by about 6 months via a network of stolons. Flowering begins 3-4 weeks after emergence and continues through the growing season. Flowering intensifies after rain or irrigation. Seeds remain viable in the ground for more than one season (Cook).

Seeding Rate
Although rates as low as 17-22 lbs./acre (15-20 kg/ha) have been recommended (Glover), higher seeding rates (40-50 lbs/acre) may be prefered to hasten groundcover establishment in fruit tree orchards (Radovich and Sugano).

Seeding Depth
1-2 inch deep (Hensley) to 1 inch (2-3 cm) deep (Glover).

Seeding Method
Drill if possible. For small areas, seed may be drilled with a hand planter. Seed can be broadcast and covered or rolled. Consider seeding with a nurse crop of buckwheat or alfalfa to control weeds during establishment (Glover).

Seeding Dates
Year round in Hawai`i. To reduce the need for irrigation during establishment, seeding should be done just prior to the rainy season.

Drilling perennial peanut seed.

Inoculation
Inoculate all propagation material (seedpods, seed, stolons) with cowpea type rhizobia (Hensley, Glover).

Seed Cost
As of 2/09/09, seed was locally available for $15/lb. 

Seed Availability
Readily available.

Days to Flowering
Flowering commences 3-4 weeks after emergence and continues through the growing season (Cook).

Days to Maturity
No information is available in this database on this topic.

Seed Production
No information is available in this database on this topic.

Seed Storage
Seed should be dried and stored under cool conditions with low humidity (Cook).

Growth Habit
Low growing and non-twining. Once established, crowds out weeds effectively. It will compete with other groundcovers (Hensley).

Maximum Height
Perennial peanut grows to a maximum height of about 8 inches (20 cm). (Cook).

Root System
It is stoloniferous and will develop a strong taproot (see above) on the older crowns as well as large numbers of nodules on both the taproot and subsidiary roots (Cook).

Establishment
Perennial peanut can be established by seed, by cuttings or by stolons. Superior rates of biomass production and leaf area are reported in plants from seed compared with those of vegetative material (Kerridge & Hardy; Mitschele).

Cuttings: Cuttings should be 4-8 inches long and partially buried 3-5 inches deep in soil in pots or a prepared seedbed. For quick soil cover, plant cuttings 10-15 inches apart. Do not allow cuttings to dry out before, during or after planting (Hensley).

Stolons (runners, sprigs): Remove stolon section from the mother plant and place 1/2 - 1 inch deep in the soil at 10-12 inch spacing. Do not allow cuttings to dry out before, during or after planting (Hensley).

Maintenance
Irrigate as needed or plant at the beginning of the rainy season (Glover).

Mowing
Mow at 2-3 inches the first year to reduce weeds and stimulate lateral growth. Subsequent mowings should be at 6-8 inch height (Glover).

Incorporation
Not applicable. Not generally used as a green manure.

Harvesting
Not generally harvested, although taller growing accessions can be used for hay making or cut-and-carry forage systems (Cook).

Equipment
No information is available in this database on this topic.

Uses

  • ‘Amarillo’ and Golden glory are used as a cover crop in fruit trees, coffee, and other crops in Hawai`i
  • ‘Golden Glory’ is a common ground cover in Hawai`I landscapes.
  • CIAT (Centro Internacional de Agricultura Tropical) releases are used for intensively managed grass/legume pastures in South America.

Mixtures
No information is available in this database on this topic.

Biomass
Above ground biomass in established (3+ years) peanut plots ranges widely (0.2 kg - 4.0 kg per square meter), depending on plant density, season, management, soil type and other factors (Mitschele). Above ground biomass production at the Waimanalo experiment station one year after planting was 1.75-4.25 kg per square meter, depending on planting material and density (Radovich and Sugano, 2009).

Perennial peanut under papaya

N Contribution
Perennial peanut may reduce nitrogen availability in the soil during establishment. Soil solution nitrate levels under perennial peanut at the Poamoho and Waimanalo experiment stations was 30-60% lower than under black weed mat one year after peanut planting (Radovich and Sugano, 2009). This effect was not observed under older, well established peanut (Mitschele).

Non-N Nutrient Contribution
No significant influence of peanut on total organic carbon in the soil has been observed in orchards on Oahu. P, K and Ca have have been observed to be lower under peanut compared to black plastic mat or bareground (Mitschele; Radovich and Sugano).

Effects on Water
Soil water retention has been reported to be higher under perennial peanut than bare ground or black plastic mat (Mitschele; Radovich and Sugano).

Effects on Soil
Soil bulk density has been observed to increase with perennial peanut density, likely a result of improved moisture retention (Mitschele).

Evolution of CO2 in soils (soil respiration) under 1 year-old stands of peanut was higher than that under black plastic mulch, indicating higher microbial activity under the peanut (Radovich and Sugano). Free-living nematode levels were low 7 months after establishment. No other data directly quantifying or qualifying soil microbial populations is available.

Effects on Livestock
Perennial peanut is used as a pasture legume in tree plantations and as an intensively managed grass/legume pasture. In vitro digestibility varies from 60-76%, N concentrations from 2.5-3.0% and P concentrations from 0.18-0.37%. It is well accepted by cattle at all growth stages (Cook).

Pest Effects, Insects
Slugs and snails can be a problem during establishment and may require control via pesticide baits. Chinese rose beetles may become a problem later on (Hensley).

Pest Effects, Nematodes
‘Amarillo’ has moderate to high resistance to various root-knot nematodes (Meloidogyne spp.) but is susceptible to the root-lesion nematode (Pratylenchus brachyurus) (Cook).

Pest Effects, Diseases
‘Amarillo’ is reported to be resistant to major groundnut diseases, rust (Puccinia arachidis) and leaf-spot (Mycosphaerella spp.). Other fungi have been isolated from leaf-spots, but no long-term or serious damage has been reported (Cook).

Pest Effects, Weeds
During establishment, weed control is needed (via mowing, hoeing, hand weeding, herbicides). Consider seeding with a nurse crop of buckwheat or alfalfa to control weeds during establishment (Glover). Once a good stand of perennial peanut is in place, weed suppression is excellent (Hensley).

Pest Effects, Vertebrates
Rats and mice are attracted to the nuts and can be a problem (Cook).

Uses in the Pacific Region
  • Kerridge & Hardy report very promising legume field trials with Arachis pintoi cv. ‘Amarillo’ in Fiji. Future experiments will investigate fertilizer requirements, seed production, and milk and meat production of cattle grazing A. pintoi-based pastures.
  • In Vanuatu, Kerridge & Hardy report several forage Arachis accessions are being evaluated as part of the Vanuatu Pasture Improvement Project. It performed well in heavily grazed Brachiaria decumbens pastures. Its value as a cover crop was unclear due to its inability to suppress weeds. Disadvantages reported in Vanuatu include: high cost of seed, rapid decline in germination percentage in humid environments, and a 12 month time span to develop an effective rhizobial symbiosis. Arachis accessions suited to low-fertility, high-pH coralline soils would be helpful to smallholders with cattle under coconuts in the Pacific region.

Uses in Hawai`i
  • A pintoi is used as a living mulch in fruit trees and other crops across the State, but is not recommended as a living mulch in short-cycle (annual) crops.
  • Clement and DeFrank conducted a field trial using ground covers during the establishment of Heart-of-Palm (1998). A. pintoi formed a closed canopy slowly and only controlled weeds after forming a thick canopy, but required less mowing after establishment. All vegetative covers delayed heart-of-palm harvest and reduced yields 1.5 years after planting (possibly due to strong competition for nitrogen). A combination of polypropylene (adjacent to plants) and vegetative covers (in service rows) may provide the best solution.
  • Subsequent trials with guava and sapodilla on Oahu confirmed nitrogen competition between peanut living mulch and fruit trees (Radovich and Sugano). Trees grown with perennial peanut ground cover had lower tissue nitrogen levels than trees grown with black weed mat. These lower tissue N levels corresponded with visibly chlorotic leaves and lower soil solution nitrate levels.
  • A farmer in lower Kula (Maui) has used A. pintoi with some success in a mixed orchard system, but has observed serious reduction in foliage as tree canopies close. This grower also suspects that competition for nutrients is greatest with shallow rooted trees like coffee.
  • A farmer in Hakalau (Hawai`i Island) reports using Arachis pintoi as a permanent live mulch under perennial tropical vegetables such as Sauropus androgynus (chekkurmanis) for many years in a permanent system. Their experience is that the perennial peanut requires extensive weed control during the first six months, if a pure stand is to be established. Eliminating most weeds prior to planting (using successive cultivations, herbicide, heat, or plastic mulch) makes establishment much easier and cheaper. After establishment, they have found that even well established plots have to be checked periodically to remove certain difficult weed species, especially vines and trailing grasses that can come in from the perimeter and can out-compete the peanut cover due to the fact that it is non-twining.
  • An organic farmer on O’ahu stopped fertilizer applications to fruit trees three years after the peanut had established, without observing adverse effects on yield. Soil tests confirmed adequate levels of macronutrients under perennial peanut (Mitschele). This grower reported increasing slug and snail populations until three years after establishment when snail population decline coincided with an increased incidence of invertebrate predators (planarians). Periodic weeding of the peanut is still required 3-5 years after establishment.
  • An organic farmer in Molokai reports having a problem with southern leaf blight on Arachis pintoi. The plant is also difficult to eradicate under an organic program without access to chemical controls.
  • Dr. Joe DeFrank, UH Manoa, reports difficulty in eradicating Arachis pintoi from a plantation, due to its ability root at the nodes.
  • In a preliminary trial on the Hamakua coast (Hawai`i Island), perennial peanut was drilled between rows of taro, survived well under heavy shade (12,000 taro plants/acre), and formed a dense cover within 6-7 months (Glover).

FOR MORE INFORMATION

Perennial Peanut Groundcover
http://www.ctahr.hawaii.edu/oc/freepubs/pdf/OF-23.pdf

Arachis pintoi Fact Sheet
http://www.tropicalforages.info/key/Forages/Media/Html/Arachis_pintoi.htm

Perennial Peanut Demonstration Garden
http://www.ctahr.hawaii.edu/ctahr2001/InfoCenter/Forages/downloadables/PerennialPeanutGarden.doc

REFERENCES

Clement, C.R.; DeFrank, J. 1998. The use of ground covers during establishment of heart-of-palm plantations in Hawaii. HortScience. Vol 33, Issue 5. pp 814-815.

Cook, B.G., Pengelly, B.C., Brown, S.D., Donnelly, J.L., Eagles, D.A., Franco, M.A., Hanson, J., Mullen, B.F., Partridge, I.J., Peters, M. and Schultze-Kraft, R. 2005. Tropical Forages: an interactive selection tool., [CD-ROM], CSIRO, DPI&F(Qld), CIAT and ILRI, Brisbane, Australia.

Cook, R.G. 1992. Arachis pintoi Krap. & Greg., nom. nud. In:’t Mannetje, L. & Jones, R.M. (Editors): Plant Resources of South-East Asia No 4. Forages. Pudoc-DLO, Wageningen, the Netherlands. pp. 48-50.

Fukumoto, G. and M. Yamasaki. 2001. Perennial Peanut Demonstration Garden. Cooperative Extension Service. College of Tropical Agriculture and Human Resources.

Hensley, David, Yogi, Julie, & DeFrank, Joseph. October 1997. Perennial Peanut Groundcover. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa, Honolulu, USA. 2 pp. Free publication available at CTAHR Website: http://www2.ctahr.hawaii.edu/oc/freepubs/

Kerridge, Peter C. & Hardy, Bill (Editors), 1994. Biology and Agronomy of Forage Arachis, (CIAT Publication; No. 240), Centro Internacional de Agricultura Tropical, Cali, Colombia. 209 p.

Glover, Nancy. August 1994. Perennial Peanut (Arachis pintoi), ADAP Integrated Farm Development Project, University of Hawai`i, 1994, 4 p.

Mitchele, B. 2007. Rapid Evaluation and Screening of Archis pintoi contributions to soil nitrate and select soil quality Characteristics as a Living Mulch System. M.Sc. Thesis. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa.

Radovich, T.J.K and J. Sugano. 2009. Enhancing Soil Quality and Fruit Tree Growth with Arachis pintoi Cover Crops in Hawai’i Orchards. HFBF project Final Report.

If you have used this plant as a cover crop in the Pacific Region, please email us with COMMENTS and FEEDBACK about this plant description so we can further refine this educational resource.

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Last updated on 5/1/2009
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