Agriculture Reference
In-Depth Information
Work in such areas should begin with treatment of the upland which constitutes
the immediate catchment of the area. Usually these are relatively flat lands with good
soil cover. Extensive soil and water conservation measures such as V-ditch or contour
trench should be adopted to minimise runoff into the gullies. The head of gullies is
treated with a series of ring trenches running on contour. The mouth of the gully
should be plugged with brushwood and stones after easing the slopes by pulling soil
flat. A comprehensive plan of seedling planting should include digging of pits in
between the contour V-ditch, and sowing of perennial grasses in other areas to arrest
soil erosion and to minimise runoff.
Slopes of the gullies should be treated individually. Contour trenches in these
will have to be planned with utmost care. Spacing between these trenches is small,
usually 4-7 m, because the extremely steep slopes often result in high runoff. Bunds
of the contour trenches should be sown with perennial and fast growing shrubs in
two to three lines. Space in between the trenches is planted with suitable species
at a close spacing, say, of 2.5 m
2.5 m. Size of the pits may be kept smaller to
compensate for the higher costs. The saucers must be made with great care and duly
compacted to safeguard against erosion of their ridges. Seeds of perennial grasses
should be sown densely to turf the gully slopes. Extensive treatment of the drainage
lines is done with check dams—usually earth-and-brushwood structures since stones
will not be available in these areas.
Species for sowing and planting in ravines should be chosen with care. Certain
species might have been known to perform better in ravines from empirical evidence,
though the basic factors of species selection (Fig. 3.5 ) should still form the underlying
criteria for decision making. Considerations such as availability of higher moisture
at gully bottom, and shortage of moisture in upper slopes (especially the aspects
facing the sun), should be taken into account to fine tune the distribution pattern of
species in different parts of the gullies.
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3.8.5
Planting Design
The treatment plan should lay down details of proposed planting operations. Issues
such as use of containerised vs. bare-root plants; species, size, and age of plants;
time of planting, and relative importance of planting vis-à-vis sowing should all be
settled. Details such as whether planting is to be done in advance of the rains, what
pesticides are to be used for treatment of pits, from where or which nursery the plants
are to be transported and how, and other such details should be set out in the plan.
The size of plants at the time of outplanting should be given detailed consideration.
This decision will affect the plan of plant-raising in nursery. Though it is always
desirable to use tall plants as far possible, certain species with a large root system
cannot be grown in containers for more than a few months without root coiling
adversely affecting their subsequent growth in field. In case of certain species, smaller
plants may even perform better than tall ones, both in terms of rate of survival and in
terms of growth. In case of certain other species, plants raised from direct sowing in
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