For coffee production in Vietnam, we strongly recommend the establishment of the perennial peanut or Arachis pintoi. Perennial peanut is used throughout Vietnam mostly as an ornamental plant along roads or highways and in city landscapes. Originating in Brazil, this tropical legume is well adapted to low fertility soils. It is a stoloniferous plant, which means it is a creeping horizontal plant that takes root along its length to form new plants. This persistent plant has an impressive list of advantages to any other tropical groundcovers, such as shade tolerance (requires only 20% sunlight), drought resistance, high growth rate, high nutrient value/protein content, and low sward height. The perennial peanut helps to control erosion and flowers, acts as a heavy nitrogen fixer, and spreads like a blanket, making it an ample ground cover. Although its growth rate is not as high as it’s temperate counterparts, such as clover or alfalfa, the perennial peanut has one of the highest growth rates for tropical leguminous grasses.
There are, however, disadvantages to using the perennial peanut. For example, it produces little biomass, lacks deep, penetrating roots to break up soil, and takes about 4-6 months to completely establish a ground cover. Given its prolonged initial growth period, weeding will be a necessity initially. It is said that perennial peanut responds best to seed planting; however, it is most commonly planted using the stolons for vegetative propagation since the seed is so difficult to harvest.
It is fairly easy to take clippings to cultivate your own plants, or you can order them at most nurseries for a reasonable price. To establish your own plants, you will need to locate an existing stand. It will be fairly obvious as you see that perrennial peanut establishes ‘runners’ or stolons to spread out. Simply cut the runners into 4 to 6 inch pieces and trim the majority of leaves. Use a rooting stimulant or rooting aid and plant the peanut in soil blocks. The trimming of excess existing leaves will fasten the rooting of the shoot ensuring a stronger and healthier plant in the long term. Thicker runners are more desirable for propagation because there is more energy in the clipping. This means that the clipping is more likely to cope with the shock of transplanting. It is recommended to treat the freshly planted stolons with some type of fertilizer application, organic or non-organic, and to keep them in the shade. You can water them with natural stimulants, like fish emulsion, EM, or seaweed extracts to speed up plant development. In approximately 1 to 2 months, the soil blocks or bags will become harder, which is a sign of ample root development. At this point, they are ready to transplant in the field.
Due to its impressive perseverance, the peanut is a perfect choice for ground covers in orchard or silviculture systems. It is tolerant to many soil types in addition to moderate salinity, hydration, and soils with high levels of magnesium and aluminum. Once established, it is great forage with high nutritional value, exhibiting a 13-25% crude protein content, a 60-70% dry matter digestibility and low levels of condensed tannins. The peanut is tolerant of heavy grazing due to its persistent stolons, making it optimal forage for chickens, ducks, rabbits, sheep, cows, and even pigs. In fact levels of fixed NH4 are increased in well managed grazing systems, further reducing fertilizer needs. For best results in grazing operations, one should plant competitive sward grasses with the perennial peanut. However, it is not recommended to plant the peanut with other legumes, as it will out compete them. Due to its low sward height, it is not favored for cut and carry applications. In an orchard setting, the peanut may creep towards the base of the tree, thereby competing for nutrients. Cutting the peanut back from the base of the tree to the edge of the coffee’s shallow roots is recommended to reduce nutrient competition while still allowing the exchange of nitrogen from the peanut to the tree. How far one decides to cut back the peanut may vary depending on the species of tree. Other leguminous plants such as Gliricidia can be chipped or manually trimmed to mulch directly under coffee trees to control weeds and retain moisture and nutrients.
Biodiversity and polyculture are key factors to any sustainable agricultural system because they aid in pest control, cut environmental impacts and can provide different means of income. Yet, it is often a struggle to convert an existing monoculture into a functioning polyculture. It can be difficult convincing a farmer to pull trees from their orchard to allow space for intercropping. It is equally difficult to try and convince a farmer to plant their cash crop farther apart. These concepts are not practical for struggling farmers. Nor should NGO’s or extension services waste their time in promoting such futile concepts. Therefore, perennial peanut provides a solution to orchards, plantations, and siliviculture. If capital raised by organizations went towards the planting of legumes and green manures, the impact would be tremendous with permanent results.
For Coffee production, the perennial peanut provides an excellent ground cover and can completely eradicate the need for herbicide applications once established. It will reduce the farmers’ needs for synthetic fertilizers while aiding in the control of erosion. Animals can freely graze the ground cover, and their manure will add to the available nitrogen for coffee production. Another advantage is that the peanut flower provides nectar for the introduction of honeybees. Coffee produces a wonderful flower for beekeeping and the combination of both coffee and perennial peanut enables the bees to have nectar all year around.
We at AGC believe that introducing the perennial peanut may be the first step to converting Vietnam’s densely planted coffee plantations into a functioning polyculture. Furthermore, the additional income generated from livestock can play a vital role in improving the livelihoods of coffee farmers. The perennial peanut can be seen as one step in the process of creating an environmentally and economically sustainable coffee plantation in the tropics. Again, farmers must understand that the initial six months will require additional labor or costs, such as planting and weeding. Yet, once established, the peanut is very hard to eradicate. Furthermore, since this crop is permanent, it ensures NGO’s of its continual presence and benefits far after these organizations have left.
Essay by Loren Cardeli and William Rutherford