Neonotonia wightii

Cultivation Details

Perennial soybean is a native of tropical Africa, where it is found at elevations from sea level up to 2,450 metres. It grows best in areas where annual daytime temperatures are within the range 20 - 30°c, but can tolerate 13 - 32°c^[1]. Mature plants can be killed by temperatures of -10°c or lower, but young growth will be severely damaged at -2°c^[1]. A survival rate of 50% of the plants has been recorded where temperatures went down to -10°c^[1]. Normally the plant has limited frost tolerance and leaf damage at 0°c occurs in all cultivars^[1]. It prefers a mean annual rainfall in the range 800 - 1,800mm, but tolerates 550 - 4,000mm^[1]. It is best adapted to summer rainfall areas^[1]. In Kenya, at the equator, it can be grown in the lowlands and up to 2,450 metres in elevation, in Colombia it can be found from sea level to 1,800 metres in elevation^[1]. Performs best in deep, freely drained latosolic soils derived from basic igneous rocks, on self-mulching black soils and fertile alluvial soils. It is not suited to acid podzolic soil or solodic soils. It prefers free-draining loams to clays of basaltic or alluvial origin^[2]. It is somewhat tolerant of saline soils^[2]. Prefers a pH in the range 6.5 - 7, tolerating 5.7 - 7.5^[1]. Established plants are drought tolerant^[1]. Perennial soybean is a vigorous, perennial, twining, leguminous vine that can smother grasses and other low-lying vegetation. It has escaped from cultivation and become a weed in areas outside its native range, and is classified as 'Invasive' in some Pacific Islands^[3].. Dry matter production may be 3.8-4.5 t/ha^[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].