Butter Yam, Yellow Yam, Cut-and-come-again Yam, Twelve Month Yam, Yellow Guinea Yam /Dioscorea Cayenensis/
Butter Yam is native to Nigeria, Ghana and other West African countries.
It is a cultivated species that is not found in the wild.
This yam is an important staple food in many countries with peelings fed to animals.
Tubers up to 3kgs have a rough outer skin and a pale yellow flesh.
Requires a longer growing season than other yams.
Mature roots are formed in 9-12 months from planting.
A yam with angular glabrous stem, usually prickly toward the base, and leaves that are deeply cordate at the base and 8-13 cm long. The flesh of the tubers is yellow. The tubers take about a year to mature. The yellow yam does not store well.
Uses
Usage
Yam can be boiled, baked or fried just like potatoes.
This yam has a very good flavour with a dry mealy flesh.
Production Requirements
Climate
Tropical and subtropical
Growth cycle
This yam is a perennial and dug up and replanted every three years.
Day length of more than 12 hours is preferred during the early growing season (late Spring to early Summer) since this encourages vegetative growth. Day lengths of less than 12 hours towards the end of the growing season (late Summer to Winter) will encourage tuber formation and development.
The vines die back in Winter and the tubers become dormant. They reshoot and resume growth with the first rain after the soil warms up in Spring.
Cultivation
For best results grow in fertile soil with plenty of organic matter
Friable and deep soils allow the tuber to expand in the ground.
Is drought tolerant and requires excellent drainage and does not tolerate water logging.
Improves yields if grown on a trellis and the vine is tipped to keep growth under control which encourages production of tubers.
Hilling the plant up also increases tuber size.
Succeeds in full sun and also in light shade.
Edible parts
Tubers – cooked
They must be thoroughly cooked in order to destroy toxic alkaloids.
The roots can contain up to 91% carbohydrate, the highest for any yam and are very low in protein.
Propagation
Plant in Spring when tubers start to shoot.
Chop tubers into large pieces with a couple of eyes on each piece.
The crown is the quickest part of the tuber to shoot and gives the highest yield.
Plant 10-15 cm deep in a mound from 70-100cm.
Risks and weed potential
Yams will produce small axillary aerial yams during drought conditions. These produce vigorous plants and have weed potential. Plants should be kept contained and every axillary yam should be collected.
Harvesting & Processing
Harvest
Individual tubers are harvested from the side annually.
Harvest mature tubers when plant growth has stopped and the leaves begin to yellow.
Mature tubers are formed in 9-12 months from planting. The tuber has a very brief resting period and so does not store well so is in fact best stored in the ground.
When harvesting yams dig from away from the plant to avoid injury to the tuber. Tubers are easily bruised and will rot if damaged.
The tubers are formed near the surface of the soil and can be carefully removed from the growing plant without disturbing it, allowing the plant to continue cropping for up to three years. This is how it has earned the name ‘cut and come again’.
This yam does not store well out of the soil and so is best harvested as needed.
