Tropical Kudzu, Maize and Peach Palms Revive Peruvian Soils

A major problem facing farmers on tropical forest soils is the spread of weeds which become increasingly unmanageable as the fertility of the soil declines. In the past, farmers simply abandoned such land to leave it fallow and cut into forest growth to find fertile land. North Carolina State University and Peruvian researchers studying ultisol and oxisol soils have found that one season's growth of nitrogen-fixing tropical kudzu (Pueraria phaseoloides) can restore the fertility levels equivalent to 10 years of traditional fallow systems. At the same time, kudzu actively competes to shut out weeds that would ordinarily overrun small fields. The research is particularly interesting because it is being conducted at a station in Yurimanguas, in the Peruvian Amazon where purchased inputs are difficult to obtain. Research at the site is oriented around the needs of local farmers, who market their crops via river transportation networks.

Kudzu incorporated after eight months followed by maize gives an excellent maize harvest without the weed problems associated with leaving the ground fallow. Tropical kudzu, unlike its temperate relative, is easy to eradicate, because it does not produce storage roots. It can either be burned off the soil surface before planting the cash crop, or slashed back and incorporated into the soil. Other researchers at the center are intercropping kudzu in a system with rice, cowpeas and indigenous peach palms. Peach palm seedlings are first planted in rows with rotations of rice and cowpeas to ensure cash flow over the first year until the peach palms shade them out. Then kudzu is planted underneath the palms, which are harvested for 'heart of palm' before they begin fruit production a few years later.

Agrichemical Age, July 1988, pages 6-10.
See also Science, Vol. 238, 11 Dec. 1987, pages 1521-1527.