Reducing On-Farm Food Losses
In the OIC Member Countries
56
per tonne, and on-farm losses of 69,000-172,000 tonnes, the economic losses of sweetpotatoes
farmers is in the range of US$6-17.2 million per year.
Table 3.5: Summary of the Volume and Market Value of On-Farm Losses of Sweetpotatoes in
Nigeria
Total Volume
Produced per
Annum
Conservative
Estimates of On-
Farm Losses
Losses in
Volume
Market Value
per Tonne
Losses in Value
3.45 Million Tonnes
($302-345 million)
2% 69,000 $87.5 $ 6 million
2% 69,000 $100 $ 6.9 million
5% 172,000 $87.7 $ 15 million
5% 172,000 $100 $ 17.2 million
Source: Based on Above Estimates.
Sweetpotatoes have a food value of 860 kilocalories per kg. The loss in food value of 69,000
tonnes of sweetpotatoes is approximately 59.34 billion kilocalories that could have fed 65,000
persons for a full year at 2,500 kcal/day.
3.2.3. Causes of On-Farm Losses
Sweetpotato is particularly productive in poor soils which makes it favorable for tropical soils
where fertilizer is not available (Martin, 1988). The local climate supports the growth of
sweetpotato, and different varieties adapt well to that particular locality. However, in the
Southwestern part of the country where there is heavy rainfall, some varieties are prone to rot
and insect infestation before they are harvested.
From observations, lack of best practices affects the quality of the produce. From the interviews
conducted, farmers that do not carry out adequate weeding for their sweetpotato farm had
issues of rot and insect infestation. In addition, this year, due to inadequate rainfall, most of the
tubers were small, especially the purple skinned sweet potato variety.
Several pests and diseases affect the quality of the sweetpotato. The sweetpotato weevil is a
major pest in Nigeria, causing losses up to 80%. Unfortunately, orange-fleshed clones have
generally been found to be more susceptible. Others include sweet potato whitefly and the
banded winged whitefly. Knot Nematode (Meloidogyne spp.) can attack sweet potato root and
cause damage resulting in crop losses of potentially as much as 20-30%, but some clones (55
reported) have been found to demonstrate some resistance (Tewe et. al, 2001). Major storage
diseases are caused by fungi and include Rhizopus soft rot, Java black rot, Charcoal rot, Black rot,
Circular Spot and Fusarium root rot, most of which gain entry when the roots are wounded
during the harvest.