Although it is uncertain from which country yams
originated, yams are one of the oldest food plants known. They have been cultivated since
50,000 BC in Africa and Asia. In addition to these continents, yams also currently grow in
the tropical and subtropical regions of North and South
Yams are one of the most popular and widely consumed
foods in the world. They play a staple role in the diets of many different countries, notably
those in South America, Africa, the Pacific Islands, and the West Indies. Yams are a good
source of potassium and vitamin C.
identified two types of
yams the White yam Discorea rotundata and Chinese
yam that offer high yields under the drought prone, shallow soil, low nutrition conditions
found in the Sartenejan Region. Yams are also disease
resistant and respond very favourably to light applications of phosphorus based
||The hairy yam is tough and high yielding
and can be grown on trellises or simply as
a ground creeper. The hairy yam is especially good for fries as it naturally forms
a crunchy coat on the outside of the fry, and also tastes better than
are researching and fostering the commercial production in the Sartenejan
Region of the two most profitable types of yams, the white yam and the
Left: in 2013 we
dug pits and mounded them with 3 yams and stakes. These yams were used to ascertain
cooking methods and to provide seed (mini-sets) for 2014.
We used the same array in 2014 and added
fertiliser to see ig yields could be maintained or improved with reuse of
plantings. In 2015 we will grow the yams in rows with only shallow pits but with
high mounds as recommended.
There are three tested methods
tested to improve the yield and profitability of white yams; 1) The use of mini-sets or vine
cuttings to improve effective yield, the 2) use of mounds to increase yields, and 3) the use of
phosphorus based fertiliser to increase yields.
In the traditional method of
growing yam, farmers set aside 25 to 30 percent of the harvested tubers as seeds for the next
planting season with the multiplication rate is only about 1:5-10 by weight. In
comparison cereals like wheat or rice that have a propagation ratio of about
Two methods have been published to
increase the multiplication rate of white yams and therfore profitability, vine cuttings and
with one to two nodes with leaves, are taken from the lateral branches of
immature healthy-looking vines before tuber enlargement, and planted into soil with
carbonized rice husks.
Once the cuttings formed roots and shoots, they are transplanted to nursery beds
where they produce mini tubers, which are then used as the planting material for
the next crop. Carbonised rice husks can be cheaply and easily
A rooted yam vine cutting, which would
soon be ready for transplanting in the field. Image by O Adebayo,
Vine cuttings make more yams are made available to farmers
for food or for sale, promotes faster multiplication and better crop quality
with nematode infestation free yams.
are yam tubers are cut up into 20-25 g pieces and used to produce planting
material for ware tuber production.
The use of mini-sets enables the production of 10 x
5 kilogram (12 lb) yams from one 300 gram (1/2 lb) yam.
of Yams (Dioscoria species) IRETA
Publication No 3/88. Jill E. Wilson and Kim Des Rochers, Carl I.
Eevensen, Shirley Tjendana. USP Institute for Research, Extension and Training
in Agriculture (IRETA). IRETA Publications USP Alafua Campus Western
To produce yams most farmers in the Pacific plant
yam setts that weigh 100 to 600 g or more. This means that they must set aside 10
to 30% of their yam harvest for planting material.
1. Minisetts should be treated and dried as soon as
possible after cutting to stop rotting.
2. Dust the cut surfaces with dry, sifted fire ash,
or beach sand (well washed or collected from above the high tide mark), or treat
with the fungicide and/or insecticide recommended in your country for normal yam
3. Air dry the treated
minisetts for 2 days, then plant them. Do NOT dry longer.
4. Dry the minisetts in a place that is shady,
well-ventilated, and protected from rain and sun. Spread them in a thin layer with
cut surfaces facing up.
5. Sprouting usually ranges from 60 to
6. The time to sprouting varies with species and
cultivar and differences in sprouting time can sometimes be a
7. It is possible to plant minisetts on shallow
infertile soils not good for growing yams for eating and,
fertiliser to increase yield
Kang BT, Wilson JE. 1981. Effect of mound size and
fertilizer on white Guinea yam (Dioscorea rotundata) in Southern Nigeria. Summary Plant and Soil. 61(3): 319-327. tested the
effect of fertiliser and the provision of mounds on the yield of white yams.
Note: 1,000 kilograms is equivalent to approximately 2,204 lbs; 1
kg = 2.2 lb; 1 HECTARE (Ha) = 2.5 ACRES.
1. Increased mound size increased yield more than fertiliser. had a more
pronounced effect on tuber yield than fertilizer.
2. Crops could be maintained for 2-3 years after bush
3. The yield for the three locations without fertilizers was 7.83 tons/ha on the
flat compared with 9.44 tons/ha (3.7 Imperial tons per acre, or 8,300 lbs per acre) on large
mound (about 30 cm height).
4. With fertilizer yields were 7.43 tons/ha on the flat and 11.30 tons/ha (4.45
Imperial tons per acre, or 9,960 lbs per acre) on large mound
Notes: Higher yield with mounds may be due to looser soil for yam
growth. Planting on large mounds also
resulted in longer tubers and shorter harvesting time.
Fertiliser (15:15:15 NPK) and yam
Law-Ogbomo KE, Remison SU. 2008. Growth and yield of white guinea yam
(Dioscorea rotundata Poir.) influenced by NPK fertilization on a forest site in
Nigeria. Journal of Tropical Agriculture 46 (1-2): 21–24,
Ridges were 1 m apart and 250 g setts were planted at 1 x 1 m
spacing to give a density of density of 10,000 plants per hectare.
The treatment with 300 kg 15:15:15 NPK per
hectare (660 lbs per hectare) resulted in the maximum yield of 24 metric tons per
hectare, or 8.86 Imperial tons per acre, or 20,000 lbs per acre.