Efficiency of water conveyance

Efficiency of water conveyance


Water Requirement

  • Every crop is requires a certain quantity of water after a fixed interval,throughout its period of growth. If the natural rain is sufficient and timely so as to satisfy both these requirements, no irrigation water is required for growing that crop.

In India, the natural rainfall is either insufficient, or the water does not fall regularly , as required by the crops. Since the magnitude as well as the frequency of the rainfall varies throughout a tropical country, certain crop may require irrigation in certain part of the country, and the same crop may not require any irrigation in some other part of the country.

Arid region-

The area where irrigation is must for agriculture is called the arid region.

Semi arid region-

The area in which inferior crops [jowar, Bajra ] can be grown without irrigation is called semi-arid region.

  • The term Water requirement of a crop means a total quantity and the way in which a crop requires water, from the time of its sown to the time it is harvested.

It is very clear that the water requirement, will vary with the crop as well as with the place.

  • In other words, different crops will have different water requirements, and the same crop may have different water requirements at different places of the same country; depending upon the changing in climates, types of soils, different methods of cultivation, and useful rainfall, etc.

Crop Rotation-

  • When the same crop is grown again and again in the same field, the fertility of the land gets reduced as the soil becomes deficient in nutrients which are required to that particular crop.
  • In order to enhance the fertility of the land it is often found necessary and helpful to give some rest to the land.
  • This can be achieved  either by allowing the land without any cultivation for some time period, or by growing the crops which do not mainly require those nutrients which are mainly required by the earlier grown crop. This method of growing different crops in rotation, one after the other, in the same field is called crop rotation.
  • The rotation of crops will help in extracting different foods from the soil, and thus avoiding the general deficiency of any particular type(s) of element(s).

Moreover, if only one type of crop is grown in the same field, numerous insects and pests (of similar nature) will get developed. The crop rotation will also help in checking such growths. Crop rotation will thus help in increasing the fertility of soil, and reducing the diseases and wastage due to insects, and hence increasing the overall crop yield.

  • In general, the following rotations of crops may be adopted depending upon the soil conditions.

(i) Wheat-Juar-Gram
(ii) Rice-Gram
(iii) Cotton-Wheat-Gram- Fallow (up to July)
(iv) Cotton-Juar-Gram.
(v) Sugarcane (18 months)- Thadwa-Wheat or gram Fallow (upto July).

Optimum Utilisation of Irrigation Water

If a crop is sown and produced under absolutely identical conditions, using different amounts of water depths, the yield is found to vary. The yield increases with water, reaches a certain maximum value and then falls down, as shown in Fig. The
quantity of water at which the yield is maximum, is called the optimum water depth.

Optimum utilisation of irrigation water

  • Therefore, optimum utilisation of irrigation, generally means, getting maximum yield with any amount of water. The supplies of water to the various crops should be adjusted in such a fashion, as to get optimum benefit ratio, not only for the efficient use of available water and maximum yield, but also to prevent water-logging of the land in question. To achieve economy in the use of water, it is necessary that the farmers be made acquainted with the fact that only a certain fixed amount of water gives best results. More than that quantity, as well as, less than that quantity, reduces the yield. Many cultivators, till today feel, that they can increase the crop yield by using more and more water. Hence, they try to supply more water to their fields by undue tapping at the outlets. This must be checked. Moreover, farmers should be encouraged to line their water courses, thereby saving at least 20% of the costly irrigation water, which can be used to irrigate extra additional fields.

Crop Seasons and Indian Agriculture

More than 70% of the Indian population is directly or indirectly connected with agriculture. The chief crops of India are rice, wheat, sugarcane, tea, cotton, groundnut, jute, coffee, rubber, garden crops (like coconuts, orange, etc), etc. Different types of soils are needed for raising different types of crops. For example, heavy retentive soil (40% clay) is favourable for raising crops like sugarcane, rice, etc., requiring more water. Light sandy soil (2 to 8% clay) is suitable for crops like gram, fodder, etc. requiring less water. Medium or normal soil (having about 10-20% of clay) is suitable for crops like wheat, cotton, maize, vegetables, oil seeds, etc. requiring normal amount of water.

  • From the agricultural point of view, the year can be divided into two principal cropping seasons, i.e. Rabi and Kharif. Normally, Rabi starts from 1st October and ends on 31st March ; while Kharif starts from 1st April and ends on 30th September. These dates are not rigid dead lines. The time may vary up to 1–3 months on either side. Sugarcane, which is an important cash crop, extends over both seasons.

Irrigation efficiencies

Efficiency is the ratio of the water output to the water input, and is usually expressed as percentage. Input minus output is nothing but losses, and hence, if losses are more, output is less and therefore, efficiency is less. Hence efficiency is inversely proportional to the losses. Water is lost in irrigation during various process and, therefore, there are different kind of irrigation efficiencies, as given below-
  1. Efficiency of water conveyance.
  2. Efficiency of water application
  3. Efficiency of water storage
  4. Efficiency of water use
  5. Efficiency of water of water distribution

Efficiency of water conveyance

It is the ratio of water delivered into the field from the outlet point of the channel, to the watering entering into the channel at its starting point. It takes the conveyance or transit losses into the consideration.