White yam or Water yam or Greater yam is native to Southeast Asia and West Africa contributes 90% of yam production in the world. Elsewhere in Africa, the white yam (water yam) is the dominant yam species. Yam is a preferred food security crop in the drier areas of Kenya. One plant is reported to be able to produce 90 kg of tubers. The tubers and larger bulbils of white yam are consumed as a starchy staple, after cooking in various ways.


Varieties Dioscorea Rotundata, White Yam, Water Yam
Seed Rate 5-6 tons per hectare
Fertilizer Rate 125-370 kg/ha of N.P.K (12.12.8)
Planting Spacing 50-100 cm between plants and 1 m row to row.
Husbandry Tuber dormancy lasts for 2-4 months after harvest. Small intact tubers (“seed tubers”) or tuber pieces weighing 50-500 g are used for planting on mounds, ridges, or on the flat. Plants are usually staked soon after emergence. Weeding is done 3-4 times during the season, using hand tools.
Pest & Diseases Pest /Diseases Symptoms Control
Anthracnose blackening and dieback of the leaves Use of resistant varieties
Mealybugs White woolly secretion Use pesticides
Maturity Duration 7-10 months
Climatic Conditions White yam grows in temperatures of 14-40°C and a well-distributed rainfall of 1500 mm per annum. It is mostly a crop of the lowlands, though it occurs at elevations of up to 2500 m. White yam is sensitive to aluminum toxicity in the soil. It thrives in deep, fertile, well drained, loose, loams and sandy-loam soils with low levels of salinity and a pH range of 4.8-8.5.
Harvesting Harvesting occurs 7-10 months after planting. Hand tools are used to dig up the tubers.
Post Harvest and Storage Although the tubers can be kept quite well, they are easily damaged during and after harvest, and must be handled carefully to avoid bruises. They are stored in cool shady conditions.
Growing Regions Coast, Nyanza and Eastern
Expected yields 10-15tons/ha for White Yam and 15-15tons/ha for Water Yam


Processing Tubers can be processed into Yam flakes or Yam flour.


Place Yams are marketed locally.
Price Kshs 5-15 per kg


Products and Uses Yam tubers are boiled or stewed as food.Processed Yam flakes or yam flour
Nutritional value – per 100 g / % Daily Values Energy: 118 / 6%; Carbohydrates: 27.9 / 9%; Phosphorus: 55.0 / 6%; Potassium: 816 / 23%; Vitamin: 17.1 / 28%.


Nigeria alone produces about 68% of the world’s yams.


Income Per Hectare: Kshs 50,000 (10,000kgs * 5/-)Cost per Hectare: Kshs. 15,000 (30% of Income).NET:    Kshs. 35,000 (70% of Income).

Break Even Yield (Where Cost=Income): = 3000 kgs per hectare.

Income Frequency: Once per year.

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