RA 00048.pdf - OAR@ICRISAT

proved postharvest grain systems are a vital need
in the developing countries.
Postharvest Grain Systems
Grain produced flows in a multitude of paths from
producer to consumer in developing countries.
Figure 1 illustrates the complexities that may be
encountered in this flow. No two countries seem
to have the same marketing patterns or networks.
Whatever pathway grain takes from producer to
consumer, the following functional elements are
involved in postharvest grain systems: harvesting,
threshing, cleaning, drying, storage, handling,
transportation, grading, marketing, processing,
and utilization.
Each functional element includes a physical
facility, its operation and management, and grain
management. Postharvest grain systems can be
divided into three subsystems: (a) the farms,
(b) the commercial operations, and (c) the government
operations.
Status and Problems
of Grain Storage
and Drying at Farm Level
In developing countries, grain quantities held on
the farm generally range from 70 to 9 0 % of the
total production. There are of course exceptions.
However, the general rule is for the major portion
of the grain produced in developing countries to
be stored on farms. Grain crops are harvested and
threshed almost always by hand except for a very
few commercial and experimental farms. All crops
harvested are, in most cases, dried by a natural,
sun drying method and stored on the farms at
some time, whether they are destined eventually
for sales or for on-farm consumption.
The storage period of grains intended for sales
may vary from a day to a few months but in many
cases the farmer sells his crops at the time of
harvest. It appears that the main factors influencing
the decision on how much to keep and how
much and when to sell are:
1. The amount of the total crop harvested.
2. Availability of alternatives for on-farm consumption.
3. Storage capacity.
4. Cash commitments (debts, supply of goods,
etc.)
5. Availability of time and labor at harvest period.
6. Availability of transportation.
7. Weather conditions.
8. Prices.
Grains are stored on the farm in various forms
of storage generally for periods up to 10 months.
The different types and sizes of traditional storage
units are constructed from locally available materials
such as mud and plant materials. On very rare
occasions nontraditional materials for a grain
storage such as metal, concrete and brick are
used. In many of the developing countries bags of
cereal grains are stored within human dwelling. In
many countries in Africa small quantities of grain
may be stored in dried gourds or other small
containers. Sorghum and millet in head are
stacked on platforms and covered with thatch to
ward off rain. The size of farm storage units in
developing countries would range from a few
hundred kg to a few tonnes. At any rate, farm
storage in most of the developing countries
leaves grain supplies vulnerable to insects, rodents,
birds, and to deterioration due to molds
(high temperature and humidity regions).
Research is under way in some areas to
develop improved storage facilities for farm use.
One of the main weaknesses in developing new
types of storage facilities for farm use in developing
countries has been the lack of socioeconomic
considerations. Can the farmer afford to build an
improved storage unit and is he willing to adapt it?
With a high cost of improved storage and the
absence of reasonable access to market by the
farmer, he may perhaps be better off to absorb
the losses he experiences rather than to invest in
improved storage.
Although there is often an expressed interest,
on the part of governments, in the need for
improved farm storage, it has become apparent
that the major emphasis is usually directed from
elsewhere. Most of the studies on farm storage
have been conducted and/or financed by multilateral
international organizations. Some studies
have been conducted by individual countries, but
such studies are exceptions rather than the rule.
In developing countries, removal of excess
moisture from crops is normally carried out by sun
and wind drying. If poor climatic conditions (high
humidity and rainfall) following harvest make this
operation impossible or extend the drying period,
quality and quantity loss may be high and rapid. In
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