Agriculture Reference
In-Depth Information
the saucers of the plants. The capacity of workers to carry water in a single head
load determines the quantity of water per plant (usually 10-15 l). Water is carried
to a plantation site on bullock carts or camel carts if employment generation is on
high priority, and in case such carts are not available it may have to be transported
by mechanised means such as tractors.
In areas of high aridity with scarce water resources, it becomes necessary to
use water with utmost economy. One such method uses earthen pots or pitchers of
2-3 l capacity with a couple of holes in the bottom. The pitchers are buried near the
roots of the plants, filled with water, and sealed. Water percolates down slowly over
a longer period and losses due to evaporation are minimised. In another method,
subsoil injectors are used to inject water underground around the root zone of the
plants, thus avoiding losses due to evaporation. In a recently developed method,
water absorbing polymers are mixed with the soil in the vicinity of roots. These
polymers absorb water—as much as a hundred times their own weight—and release
it gradually as moisture level goes down. Such methods should be considered when
scarcity and cost of transportation of water so warrant.
Loss of water by evaporation from the surface of ground is minimised by hoeing,
but it can also be reduced by applying a suitable mulch cover in the saucer bed.
Mulch in form of pebbles, gravel, mines waste, or coarse sand can be spread over
the bed of a saucer in a layer 5-10 cm thick. Use of leaf litter and straw may be made
but it should be avoided where it can attract termites. Polythene sheets—including
the polypots removed during the operation of planting—can be spread on the ground
around the plant and some pebbles or boulders may be kept on it to keep it in place.
This prevents loss of moisture by evaporation and also suppresses growth of weeds.
Watering should always be followed by hoeing. The effect of watering will be
negligible if no hoeing follows, except in case of sand dune plantations where the soil
is always in a perfectly hoed condition. In heavy soils loss of subsurface moisture will
be very deep and complete if hoeing is not done within a week or two of watering.
The schedule of watering should therefore always be in tandem with that of hoeing.
6.11
Fertilising and Manuring
Fertilising may not be required in practice in conservation afforestation programmes
where ground cover is the main objective rather than the productivity per unit area.
However, in case of tree planting in urban areas and other high value plantations
the use of fertilisers may be warranted. Fertilisers may also be required in highly
nutrient-deficient soils where the rate of establishment of plants is too low. Fertilisers
such as diammonium phosphate (DAP) and urea can be used in such plantations. The
DAP is used in a basal dose in the pit—about half a kilogram of fertiliser should be
mixed with the soil to be refilled in the pit while planting. Urea can be given during
watering or just before rainfall. In each dose about 10-20 g of urea should be spread
around the plant in a ring shape and covered with soil. Dissolving urea in irrigation
water will not be effective because most of the water is absorbed by soil away from
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