On-farm seed storage in Africa
It is estimated that 80% of all seed used by farmers in the
tropics is derived from stocks held on-farm from previous seasons. If yields are
to be sustained and even increased it is essential that seed storage is of a
consistently high standard. Good quality seed is central to productive
agriculture. Poor planting material results in poor field establishment and
ultimately poor yields, irrespective of subsequent inputs.
Farmers choose to maintain their own seed stocks for a variety
of reasons: the formal seed sector cannot, or does not, provide those varieties
which farmers prize; the cost of buying fresh seed of 'improved' varieties on a
regular basis is prohibitive; and because it appears that farmer selection of
seed stocks often allows maintenance of yield levels under small-scale
conditions. Because of the relatively small quantities involved and because
sorting and planting are done by hand, farmers can select the largest seeds and
those that are free of insect and mould attack, thereby ensuring plant-seeds
with maximal vigour.
Despite this preponderance of farmer-held material, very little
attention has been directed towards assisting farmers in maintaining their seed
stocks in the best possible condition. Grain stored for food and grain held as
seed face many of the same problems, such as insect and rodent infestation and
mould attack, and hence many lessons learnt from experience with grain storage
can be applied to the seed situation. However, food grain seeds are only useful
if they remain viable. Since seeds are more sensitive to the effects of
temperature and humidity than food grain stocks, they need to be handled with
additional care in order to maintain their germination potential.
Agricultural development programmes that have a seed component
often start with the premise that on-farm storage of seed must necessarily be
inadequate and in need of improvement. These assumptions are rarely supported
with survey or experimental data and their validity needs to be questioned.
With increasing appreciation of indigenous technical knowledge
some studies have been undertaken to document farmer seed-saving practices.
These studies show that farmers actively select planting material which they may
then handle and treat in a different way to their food grain.
In Zimbabwe detailed qualitative studies show clearly that
farmers have an extensive understanding of techniques which maximize seed
performance. Such documentation of farmer practices is extremely useful but it
is also important that some quantitative measure of success can be attributed to
the various techniques. The organization Seeds of Survival working in central
Ethiopia has, from preliminary data, established that germination levels of farm
saved seed, from a variety of crops, was above 70% after six months storage in
85% of their samples. These findings are supported by a more extensive survey
undertaken by staff of the Natural Resources Institute, UK, with collaborating
national institutes in Ghana, Malawi and Tanzania. A total of 1,859 samples of
five important crops were taken from farmers' seed stocks and assessed for
germination potential just prior to planting. Maize, cowpeas and soya showed
mean germination levels of above 75% whilst beans and groundnut were less
consistent, though still good.
Until now, these quantitative studies have been carried out in
countries or regions where the climate is conducive to successful seed storage,
having significant dry seasons during which seeds can be conditioned before
being placed in store. Whether or not farmer techniques are equally successful
under hot humid conditions has yet to be established.
In terms of volume, farmer seed requirements are often small.
This means that farmers can invest more time, effort and care into the
maintenance of seed quality than would be practicable for food grain stocks.
Often this simply means using a sealable container to prevent insect attack.
Alternatively, farmers apply traditional or insecticidal admixtures to control
or prevent insect infestation. For example, some farmers in northern Ghana mix
their cowpea seeds with shea nut oil, which appears to have an excellent
repellent effect on bean bruchids. Other farmers, who store their maize seeds as
suspended cobs, cover them with plastic sheeting or gourd shards as rat guards.
These farmer initiatives are often very localized, despite being
useful components of a seed storage strategy. Further studies would allow
extension staff to decide which of these indigenous practices could usefully be
more widely advertised. In addition, strategies that already have proven
advantages but which are not universally adopted, should be promoted: for
example, the selection of maize seed at harvest rather than just before the
following planting season.
Is change necessary?
In the areas investigated it seems unlikely that at the farmer
level, seed storage practices need to be drastically altered. Farmer techniques
work sufficiently well and the only rationale for a radical change m storage
practices would be if some major external change took place. This could include
declining availability of traditional materials used as admixtures such as
botanical insecticides because of over-cropping, unusual weather patterns, or
the appearance of a novel pest against which traditional measures are
ineffective (e.g. larger grain borer).
It is clear that in zones that have a climate suited to seed
storage, farmers are frequently very accomplished at E maintaining the viability
of their own seed stocks. The techniques employed, which may have evolved over
considerable periods of time, are usually well adapted to the farming. system in
which they are used. However, there is room for improvement to many of the
current practices through farmers learning from each other.
Change can be brought about through awareness activities. This
could take several forms, such as direct advice or through information
exchanges, allowing farmers to become aware of techniques used successfully in
other areas of the country. In this respect researchers and extension staff are
most suited to act in the role of facilitators through the establishment of
'best practices' from among the range of techniques available, supporting
farmer-based technologies and only offering totally new practices where the
local systems can be shown to be