Agriculture Reference
In-Depth Information
6.14
Maintenance of Soil and Water Conservation Structures
S&WC structures such as contour trench, V-ditch, contour dike, and check dams
should be repaired and maintained from time to time. If not maintained, a small
damage in one season will get magnified during the next season and the structures
may become ineffective or even counterproductive (e.g. a source of soil erosion).
Constant maintenance will prolong life of the structures and make them effective in
serving the purpose for which these were created.
A contour trench or V-ditch may get breached on bund in a heavy rainstorm. If
not repaired immediately, it will be ineffective in harvesting water during all the
subsequent rains. A breach of even a short length may render a 100 m-long structure
ineffective. Similarly, trenches may get silted up with soil transported by water. These
should be de-silted by excavating the silt and depositing it on the bund in order to
restore their water harvesting capacity.
A contour dike may be breached in a small section as a result of which most
of the soil that may have been captured will go down the slope, if the dike is not
immediately repaired. It is necessary, therefore, to watch the structure constantly and
to repair it immediately on breach or washout.
Check dams of dry stone masonry may get carried away by fast flowing water or
get de-shaped. These should be repaired and reconstructed with modifications that
will preclude such damage in future. If stop dams are damaged or breached, these
must also be repaired to salvage the expenditure already sunk into the structure.
Vegetative barriers created by sowing or planting should be maintained by resow-
ing or replanting as may be necessary. In case of sowing, it is unlikely that the first
sowing alone will result in an effective hedge or barrier. It will almost always be
necessary to redo the sowing work. In rare cases, the planted seedlings may also be
replanted in the current or the next season along with the general work of casualty
replacement in the plantation.
6.15
Plantation Maintenance in Sand Dunes
Plantation establishment in moving sand faces special problems due to the mobile
soil. The ground profile of sand dunes keeps on dynamically reconfiguring as a result
of shifting of large masses of sand. Fencing posts once fixed at ground level may get
buried in sand or may get exposed and perched atop the ground, or these may even be
dangling in the air. The same can happen to the plants also. It is necessary therefore
to take care of these adversities and maintain the fence and the plants properly.
It should be a regular exercise in dunes to dig up buried fence posts, lift these above
ground level, and refix. For this purpose, the fence wires may have to be untied, and
retied after refixing the posts. In other cases, where the posts get uprooted, exposed
to bottom, or hung up in the air, the wires should be untied, the posts freed, and
after refixing posts the wires should be tied again. It is, therefore, desirable to fix
fence posts in dunes with precast cement concrete blocks rather than cast them in
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