Page 211 - Bahrain Gov annual reports (V a)_Neat

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In Bahrain where the quantity of animal manure is limited, efforts should be made to
produce as much compost as possible and where green manuring is essential a crop such as
Scsbania aculeata, Crotalaria juncca, or lucerne, which is no longer an economic proposition,
should be selected as they can be grown with the minimum inconvenience and loss of income
and sufficient time should be allowed for the organic matter to decompose. As nodulation is
poor in Bahrain innoculation of the seed should be carried out before planting.
Farmyard manure varies considerably in composition and the two most important factors
in determining the concentration of plant food arc the water content of the manure and the type
and quantity of litter in the manure. The retention of the liquid portion of manure is very
necessary as the plant nutrients in urine are readily available to plants whereas more than half
the nutrients in the solid portion of manure are only slowly available to plant growth.
Due to the fact that many farmers do not appreciate the perishable nature of farmyard
manure, losses in handling are often very high. In Bahrain the two main sources of loss are
through volatization when manure is spread on the surface of the soil and through not retaining
the liquid part of the manure. The loss in the latter case is very serious and amounts to more
than half the nitrogen content and practically all the potash.
To control losses as far as possible, manure should be piled in a compact mass, kept
continually moist and should be lightly worked into the top soil when applied in the field.
The tendency in modern fertilizer programmes is to apply animal manures to highly
valuable cash crops and to land that is low in fertility. As manure is subject to the law of
diminishing returns moderate applications are made and where necessary it is reinforced by
the addition of applications of compost and artificial fertilisers.

Minerals in relation to Plant Growth.
Although numerous minerals are found in plants not all are nccccssary to plant growth
and they can be divided into two classes, essential elements and minor elements. For practical
purposes the three main elements are nitrogen, phosphorus and potassium and they are usually
artificially applied to the soil in the form of manure or commercial fertilizers.
A deficiency of available nitrogen results in plants of poor quality, the leaves arc usually
light green in colour, growth is stunted and stalks are slender. Provided sufficient available
nitrogen is present, stem and leaf growth is encouraged and plants arc able to make better use
of phosphorus and potassium compounds. A phosphorus deficiency results in delayed
maturity, poor plant growth and reduced root development. Top foliage is often dark green
in colour while the lower leaves are yellow and growth is stunted. Potassium plays an important
part in the health and vigour of plants, tends to balance any excess of nitrogen and phosphorus
and helps to counteract diseases. In potash starved land, grain crops tend to lodge, while in
lucerne and vegetable crops the tips of the leaves are often dotted with white or yellow spots
which later turn brown and fall out presenting a ragged appearance.
In the application of manures the farmer is invariably faced with the problem of which
fertilizer to use, when to apply it and where it should be placed in relation to the root zone of
the crop to be planted. Generally speaking nitrogeneous fertilizers give the best results in
areas where little or no manure has been used, where the soil is sandy and low in fertility and
when leafy vegetable crops are to be grown. Nitrogen also has a marked effect on pasture
grasses, circubits and some grain crops.
Phosphatic fertilizers give the best results where soil is low in organic matter and on areas
where lucerne has been grown over a long period. Potash requirements in irrigated areas are
usually low and deficiencies are sometimes apparent in sandy soils or where a crop such as
lucerne which feeds heavily on potash has been grown over a long period.

Vegetable Crops
Vegetable growing being an intensive type of farming the cost per acre is relatively high
and to be an economic proposition returns must be substantial.
In saline areas under arid conditions the problems and difficulties that have to be sur­
mounted arc appreciably increased and although it may be possible to produce a crop it is not
always possible to obtain vegetables of high quality in sufficient numbers to prove an economic
proposition.