Page 209 - Bahrain Gov annual reports (V a)_Neat

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FORAGE CROPS
Fairly High Moderate
High Tolerance Tolerance Tolerance
Barley (hay)
Bermuda Grass
Flax
Guinea Grass
Bersccin
Lucerne
Rhodes Grass
Sunda Grass
GRAIN CORPS

Barley Wheat
Oats
Sorghum (Var.)

Plant symptoms with regard to injury from salt are hard to define as confusion may arise
between symptoms of low fertility and saline injury. Low fertility can usually be recognised
when plants arc seen to be stunted and the leaves have a light yellowish green colour although
in the low lying areas in Bahrain these symptoms may also be due to waterlogging. Plants
such as lucerne, sugar beets, peas and beans are usually affected by salinity and appear to be
stunted and often have a deep bluish green colour with a pronounced waxy appearance. Cereals,
on the other hand, appear to have a reddish tinge and in some tree crops the edges of the
leaves have a scorched effect. The management of crops grown in saline areas is further
complicated by the fact that it is extremely difficult to detect wilting and to know when to
irrigate.
Field Application and Conservation of Water.
The field application and conservation of irrigation water in Bahrain leaves a lot to be
desired. In many instances insufficient thought is given to the layout of gardens, adequate
levelling with a view to water distribution, the water table and the best method of obtaining the
maximum water supply without losing an appreciable quantity in the irrigation channels
through percolation.
Water conservation seems to play a very small part in local agriculture and the wastage of
water through defective wells and .failure to shut off irrigation water when it is not required,
leads to a very appreciable loss of water and in some instances to serious waterlogging. At
present no hard and fast rules can be laid down with regard to the water requirements of
various crops as not only is the variation considerable, but the maximum demands also depend
to a certain extent on the season and a further complication is the fact that high concentrations
of salt restrict plant growth and make additional irrigation essential. Although plant growth
may be increased rapidly by increasing the water supply a point is eventually reached when
some other limiting factor impedes growth and further additions of water tend to decrease
yield. To obtain the best results it is essential to combine a high state of fertility with liberal
applications of water.
Drainage
Natural or artificial drainage is very essential in all cultivated area under irrigation. In
areas affected by salinity the need for efficient drainage is increased as very large quantities of
water are usually applied and not only must the drainage system remove the excess water, but
also the rapid build-up of salt in the soil. In Bahrain the beneficial effect of efficient drainage
is not realised and consequently many areas are waterlogged and the water table is rising
steadily.
A well-planned drainage system ensures the removal of excess water, improves the soil
structure, increases the depth of the rooting zone, allows increased bacterial action to take
place, helps to leach out salt and prevents it from rising to the surface of the soil. The damage
to crops from a high water table is very appreciable and even a temporary rise may reduce
plant growth and have a deleterious effect on yield.