Macrotyloma geocarpum

Cultivation Details

A plant of the drier to wet tropics, where it is cultivated at elevations up to 1,600 metres^[1]. It grows best in areas where annual daytime temperatures are within the range 18 - 34°c, but can tolerate 12 - 38°c^[2]. It prefers a mean annual rainfall in the range 600 - 1,200mm, but tolerates 450 - 3,000mm^[2]. Requires a position in full sun^{[3, 2]}. Grows best on a slightly alkaline, well-drained, sandy loam^{[3, 2]}. Many cultivars are tolerant of relatively poor soil conditions^[3]. Often found growing on acid soils with a pH of around 5^[1]. Prefers a pH in the range 7 - 7.5, tolerating 6 - 8^[2]. Flowering starts 30 - 65 days after sowing and may continue until the plant dies^[1]. Self pollination is the rule and 2 days after fertilization a stalk is formed at the base of the ovary, carrying the ovary to the ground. This mechanism is similar to that in groundnut, but different from that in bambara groundnut, where the peduncle grows to the ground^[1]. Plants take 3 - 5 months from sowing to produce a crop^[3]. Pods mature either on the soil surface or 1 - 2cm under it^[1]. Yields of 450 - 500kg per hectare of the dried seeds can be expected^{[3, 2]}. There are some named varieties^[3]. The seeds play an important role in traditional customs in West Africa, particularly in Togo, where they are used in funeral ceremonies of the Kaby and Mauba people. This seems to have contributed largely to the survival of the crop in northern Togo^[1]. This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby^[4]. When removing plant remains at the end of the growing season, it is best to only remove the aerial parts of the plant, leaving the roots in the ground to decay and release their nitrogen.