RA 00048.pdf - OAR@ICRISAT

(Neweke 1980). Periods which require intense
labor (planting, harvesting) often cause labor
shortages and result in reduced crop yields.
Therefore, adequate planting and harvesting
machinery for the Asian rice farmer are being
developed (Anon. 1981b).
Developing machinery for many cropping systems
is not difficult. Some modification of existing
machinery will suffice. The difficulty arises when
mechanizing the operations of mixed cropping
systems which traditionally have depended on the
use of hand tools (Erbach and Lovely 1976).
The economics of buying machinery is a serious
constraint. In many cases, the cost of a machine is
not in proportion to its size. A small tractor has
essentially the same building requirements as a
larger tractor.
Mechanization can result in unemployment
(Erbach and Lovely 1976) and can cause serious
problems. However, studies comparing animalpowered
farming with tractor-powered farming
showed that although the mechanized farm had a
lower total labor requirement the amount of hired
labor was greater than the traditional farm (Anon.
1981b).
Future Considerations
There are many opportunities for improving crop
production and management. Variety and hybrid
improvement with respect to general adaptation,
grain quality, insect and disease resistance will
always be a major objective. This is probably a
technological improvement which is most readily
accepted by farmers. However, there are areas
which require specific adaptation. Certain soils are
either deficient in certain minerals or have toxic
levels. Brown and Jones (1977) have been able to
obtain plants which grow well on soils deficient in
iron, zinc and copper or at toxic levels of aluminum
and manganese. The possibility of selecting nitrogen
efficient genotypes exist (Maranville et al.
1980). Stress tolerances to high and low temperatures
as well as drought are necessary.
Water is a resource which is becoming scarce
in many areas because of well-irrigation reducing
the water table at a higher rate than the normal
recharge. Maize is usually grown because of its
responses to irrigation, but the development of
sorghums with high yields with limited irrigation
could result in stabilization of water for these
areas.
Minimum tillage systems retain considerable
amounts of residue on the surface resulting in
insulation and reduced soil temperatures at normal
planting periods. This is especially serious in
northern temperate areas. Selection of genotypes
with cool tolerance for germination and emergence
is needed (Nordquist and Wicks 1976).
Minimum tillage for water conservation, erosion
control and improved soil characteristics should
be considered for some arid lesser developed
countries. Similarly with the introduction of any
new cropping system, a definite procedure for
testing and selecting adapted genotypes is
needed. In many cases, unique cultural procedures
should be adopted in a breeding program.
For example, the Egyptian farmers begin to
harvest the lower leaves of sorghum and maize
for forage soon after anthesis. This can continue
until only a few leaves remain. This operation
could easily be adopted in a breeding program for
selection of improved varieties.
Biological fixed nitrogen may be one of the
more productive areas for research. Traditionally,
cereal-legume cropping systems have been used
for the nitrogen fixing benefit of the legume.
However, the exact mechanism involved for the
cereal crop response is not known. Research
should be directed to understanding this response.
There are also associative nitrogen fixing
systems which are unique to grasses (Dobereiner
and Day 1975; and Singh et al. 1980) which
should be explored fully.
Mechanization of crop production operations is
necessary when labor becomes limiting or expensive.
To mechanize requires capital and larger
farming units which are usually main constraints
in developing countries. Development of improved
mechanized systems to reduce labor
requirements and accelerate cultural operations
seems plausible in place of a machine for every
farmer. As an example, the Egyptian farmer
harvests and bundles wheat by hand and then
transports the bundles to a central area for
threshing with a small engine powered thresher.
The grain is then cleaned by winnowing. This
harvesting operation could be improved by modifying
a small readily available forage cutter for
harvesting. A custom or cooperative combine
could be used as a stationary machine for
threshing and cleaning the wheat in one operation.
The combine could easily be moved from
one farmer's field to another. This system will also
allow shortening the time between harvest and
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