The correct choice of variety, or cultivar, is also important. Most crops have
varieties that have been specifically selected for their drought resistance, such as
Kalahari maize. Of course, these drought resistant varieties normally yield less than
varieties that need more water.
The growth habit of plants is also relevant to the survival of plants in arid conditions.
Cereals, for example, can totally fail to produce grain if there are high temperatures and
moisture stress at flowering, even for quite short periods.
Other crops such as legumes may only lose a small part of their overall production in
similar stressful conditions because they flower over a much longer period. This so-
called indeterminate growth habit, as opposed to the determinate habit of cereals, is
discussed in 1Ei, page 42.
Food growers and farmers can help to some extent to reduce water stress of plants:
water, some of which prevent the available rainwater from running off the field by the
construction of ridges or bunds. These are raised rows of earth and stones constructed
along the contours on sloping ground; or on level ground where they are built around
small groups of plants, or even individual plants or trees.
Some other water conservation techniques are discussed later on, such as mulching,
green manure, use of shadow, crop rotation, catch crops, cover crops etc.
varieties to grow, when to plant them and how to take care of them can produce crops
where their neighbours lose everything. Sensible farming practices such as mixed
cropping, staggered planting times, mulching and crop rotations, together with soil and
water conservation techniques, can all be used to produce healthy crops even in very
arid conditions.
produce a bumper harvest where a field infested with weeds produces nothing, a subject
plants can only use fertiliser if it is in moist soil and if it is near to the plant roots. Low
10 TONY WINCH
- Conservation of Water. There are a vast number of techniques to conserve or “hold”
- Crop Management. Farmers who make wise decisions about which crops and
- Weed Control. In arid regions, and elsewhere also, a “clean” (weed-free) field can
- Fertiliser. Application of fertiliser is not always successful in arid regions since
discussed in 1L. “Weeds”, pages 88–92.
- Fallow. If level land with a good soil depth of loam or clay is bare fallowed or clean
fallowed for one or more rainy seasons, this makes stored moisture available for the
next crop. Bare (or “clean”) fallowing is the practice of leaving a field unplanted, with
no crop growing—the field should be kept free from weeds and preferably covered with
a mulch. Fallowing is not possible in many areas where land is in short supply, but it
can sometimes ensure that at least some yield is produced on some parts of the farm
where continuous cropping could result in crop failure all over the farm.