IRRIGATION
Three basic requirement of agricultural production are soil,
seed, and water. Additionally , fertilisers, insecticides, sunshine, suitable
atmospheric temperature, and human labour are also needed. Of these , water appears to be the foremost important
requirement of agricultural production. the appliance of
water to soil is essential for plant growth and it serves the following functions(1):
(i) It supplies moisture to the soil essential
for the germination of seeds, and chemical and
bacterial processes during plant growth.
(ii) It cools the soil and therefore the surroundings thus making the
environment more favourable for plant growth.
(iii) It washes out or dilutes salts within the soil.
(iv) It softens clods and thus helps in tillage
operations.
(v) It
enables application of fertilisers.
(vi) It
reduces the adverse effects of frost on crops.
(vii) It
ensures crop success against short-duration droughts.
In several parts of the planet , the moisture available within the root-zone soil, either from rain or from
underground waters, might not be sufficient for the requirements of the flowers . This deficiency could
also be either for the entire crop
season or for only part of the crop season. For optimum plant growth, therefore, it becomes necessary to form up the
deficiency by adding water to the
root-zone soil. This artificial application of water to land for supplementing
the naturally available moisture within the root-zone
soil for the purpose of agricultural production is termed irrigation.
Irrigation water delivered into the soil is usually more than the requirement of the crop for building plant
tissues, evaporation, and transpiration. In some cases the soil could also be naturally
saturated with water or has more water than is
required for healthy growth of the plant. This excess water is as harmful to the
expansion of the plant as lack of
water during critical stages of the plant
life. This excess water are often naturally disposed of only if the natural drainage
facilities exist in or round the irrigated
area. within the absence of natural drainage, the surplus water has got to be
removed artificially. the synthetic removal of the excess water is termed drainage which, generally , is complementary to irrigation.
To keep the optimum content of water in soil, irrigation
supplies water to the land where water is deficient and drainage withdraws water
from the land where water is in excess. The
object of providing irrigation and drainage is to assist nature in maintaining
moisture in the root-zone soil within the
range required for max agricultural production. Usefulness and importance of irrigation are often appreciated
by the fact that without irrigation, it would have been impossible for India to have become self-sufficient in food
with such huge population to feed. Primary source of prosperity in Punjab is
irrigation. Irrigation from the Nile is
that the source of food, life, and
prosperity in Egypt. Similarly, without drainage, large parts of the Netherlands and
therefore the coastal regions of several
countries would always be under water.
Irrigation schemes are often broadly grouped into two main categories: (i) surface
water irrigation
schemes, and (ii) spring water irrigation schemes. the previous use
diversion and storage methods and acquire their
supplies from rivers. spring water irrigation schemes use open wells, and deep and shallow tube wells to lift water from the
water-bearing strata below the earth’s
surface. the selection of an irrigation scheme depends on several factors,
such as surface topography, rainfall
characteristics, sort of source available, subsoil profile, etc. One should, however, always decide to use
surface and ground waters together to derive maximum benefits. Such use is termed conjunctive use of
surface and ground waters.
In India, the sites for diversion structures without storage
potential from major river systems are now difficult to seek out .
Therefore, further use of surface water has
got to be through storage methods only. India isn't blessed
with really good storage sites, particularly within the Himalayas,
as are often noted from Table 1. which provides the
storage for some major dams in the Himalayas also as in other
parts of the world.
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