Industrial Crop: Starch  Management: Standard  Minor Global Crop  Staple Crop: Basic Starch

A plant of the moist, lowland tropics. It grows best in areas where annual daytime temperatures are within the range 20 - 30°c, but can tolerate 12 - 38°c[ 418 ]. It can be killed by temperatures of 9°c or lower[ 418 ]. It prefers a mean annual rainfall in the range 1,200 - 2,600mm, but tolerates 900 - 4,000mm[ 418 ]. It prefers a well-defined dry season of 2 - 3 months[ 418 ]. This species is more tolerant than most other yams of temperatures below 25°c[ 300 ]. For best yields, this species requires a deep, well-drained, sandy loam that is not liable to water-logging[ 300 ]. Prefers a pH in the range 6 - 6.7, tolerating 5.3 - 8[ 418 ]. Daylengths of more than 12 hours are preferred during the early growing season since this encourages vegetative growth; daylengths of less than 12 hours towards the end of the growing season will encourage tuber formation and development[ 300 ]. The bulbils are produced in 5 - 6 months from planting, though some forms can produce a crop in as little as 3 months[ 300 ]. Average yields of the bulbs are in the range of 3 - 5 tonnes per hectare, though up to 15 tonnes have been obtained[ 300 ]. The bulbils of selected cultivars tend to be angular with a flattened shape and a skin-colour which evokes the name 'turkey liver yam'. They may attain as much as 2 kg in weight but an average weight is about 0.5 kg. Races with increased bulbil production tend to show a reduction of the tuber, and in those with the highest bulbil return the tuber is but a woody rootstock[ 332 ]. Bulbils are ready for harvesting when they fall off the plant at a slight touch[ 332 ]. When produced, yields of 2 - 8 tonnes per hectare of the roots have been obtained[ 300 ]. There are some named varieties[ 300 ]. Aerial yam is a species of many races[ 332 ]. The wild ones, which are toxic raw, have globose, dark brown to liver-coloured, non-angular bulbils which serve as a famine-food, as do the tubers[ 332 ]. Wild strains are often planted intermixed with or on the perimeter of plantings of improved races as a protection against thieving[ 332 ]. Cattle eating them accidentally may be fatally poisoned showing frothing at the mouth and bloating[ 332 ]. The species is in the process of ennoblement and selected cultivars show in varying degree bitterness and poisonousness. Of some races even after prolonged preparation the bulbils remain bitter. Superior races are said to be very palatable and sweet, and to be entirely free from toxic substances so that consumption, even raw, is safe[ 332 ]. The skin is grey, lighter coloured than the wild forms, and the flesh is pale yellow to near white[ 332 ]. A dioecious species, both male and female plants need to be grown if seed is required. Flowering time: Late Fall/Early Winter. Bloom color: Pale Green Green

Carbon Farming

• Industrial Crop: Starch  Materials and chemicals include bioplastics, paper, cardboard, solvents, paints, glues etc. Plants are usually pods, starchy fruits, nuts & seeds, starchy trunks.
• Management: Standard  Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.
• Minor Global Crop  These crops are already grown or traded around the world, but on a smaller scale than the global perennial staple and industrial crops, The annual value of a minor global crop is under $1 billion US. Examples include shea, carob, Brazil nuts and fibers such as ramie and sisal.
• Staple Crop: Basic Starch  The Carbon Farming Solution. Eric Toensmeier.