Importance and Types of Surface Irrigation System
Various systems of irrigation are available that suit different crops, topography, soil types, water resources, climatic conditions, and costs.
Major systems of irrigation are :
(a) surface irrigation system
Surface Irrigation System
In this system, water is directly spread through gravity flow to the surface of the soil from a conveyance system, channel, or pipe located at the upper reaches of the field. For the efficient use of water, it is important to select the correct method of surface irrigation and the method of selection depends upon the soil characteristics and suitability of the crop
For irrigation with the surface system, fields are laid out every time before the crops are sown since these layouts are destroyed during preparatory tillage. In some instances, the same layout may be used for irrigating the subsequent crop. However, the field must be leveled well to achieve a higher water application efficiency.
Methods of Surface Irrigation System;
1) Hand watering
2) Free or Uncontrolled flooding
3) Check the flooding basin
4) Border strip
(1) Hand watering;
Water is carried in a bucket or any other container and either poured at the base of the plantar sprinkled or splashed over the foliage of the plant. Individual plants are watered in this way in a small-scale garden (home garden, kitchen or nutrition garden, composite garden) or during transplanting of seedlings, saplings, stocklings, cutting of vegetables, flowers, tobacco, perennial fodders, etc. More time is wasted but intensive care is taken.
(2) Free or Uncontrol flooding;
In this method, water is allowed to flood the entire field in an uncontrolled way. This method is practiced largely where irrigation water is abundant, inexpensive, and harmless to the soil and crop. This method is adapted in wetland rice where water may be applied as a continuous flood, rotational flood, or intermittent flood.
Advantages of free flooding ;
1) There is no need for land leveling and shaping of the field.
2) Zero land area is utilized for Irrigation.
3) This method does not require any supervision of water
Disadvantages of free flooding;
1) Quantity of water is lost is quite high due to deep percolation and surface water runoff.
2) This method does not support the proper field management
However, This method is good if we are adopting green manuring practices because it helps the anaerobic decomposition of organic matter in situ.
(3) Controlled Surface Flooding;
a) Basin Irrigation ;
A basin is a flat piece of land surrounded by checks or levees. On essentially level ground the shape and size of basins depend mainly on the soil characteristics, the available streamflow, and the cultivation practices.
Basins, rectangular or square, with sizes varying from about 10 to 100 sq m or even more are used. The basins are leveled in both directions. A supply ditch is aligned along the highest contour. Individual fat basins are connected one after another with this ditch breaching or by setting portable siphons. After irrigation, the breached bank is blocked and patched up or the siphon is removed
This method is well suited to all irrigable soils and to a variety of crops, Crops, susceptible to complete saturation of the root zone such as potato, maize tobacco, and chilies cannot be irrigated by this method.
Slopes up to 2 – 3% percent can be irrigated by using this method with good control of irrigation water and high application efficiency. On steeper slopes, this method can be used after proper terracing.
1. uniform application of water to the entire field
2. The small streams can also be utilized for the irrigation of crops efficiently.
3. This method is very simple and cheap when equipment is used for constructing bunds
1. Proper land leveling is a challenge for the distribution of water in the plot evenly.
2. Approximately 30 % of the area is lost under field channels and bunds
3. Bunds put a hindrance in working of inter-cultivation equipment
4. Extensive labor requirement for field layout and irrigation
b) Ring basin
This method is commonly used for widely spaced crops to irrigate an individual plant or plants grown in pits or pockets. A ring or flat basin is made around the plant and a number of plants or pockets are connected with a ditch passing between rows of plants. The soil around the plant is soaked with irrigation water and not the entire field. This method considerably economizes water. Crops, such as sweet gourd, pumpkin, and ash gourd are irrigated by this method. This is a very common method of irrigation to orchard crops
1. High irrigation application efficiency can be achieved with the properly designed system
2. Skilled labor is not required
1. labor cost in this system is quite high
2. Bunds puts a restriction on the use of modern machinery in the field
3. Limited to relatively uniform lands
(4) Border strip;
In this method the field is divided into the number of the field is divided into a number of long narrow strips, with small paralleled ridges on the sides. The strips are 2 to 10 m wide. The length of a strip ranges from 10 to 300 m or more depending upon the slope and flow size Individual strips are level perfectly and connected with the supply ditch laid out at the upper elevation. After irrigation, these are disconnected e suited well to all irrigable soils and to closely spaced row crops, and even pasture crops that can tolerate saturated soil conditions for an hour or so. Wheat, barley, rape and mustard, peas, beans, grams, nurseries of rice, and onion are irrigated by this method. Slopes up to seven percent can
be irrigated when the pasture crops are grown. On steep slopes, this method can be used by proper terracing or trenching along the contours to avoid the shifting of soil.
For laying out border strips, the land needs to be graded uniformly to achieve a high application efficiency of water. Repair of ridges and supervision during irrigation is needed.
1. In the border strip method large water streams can be utilized safely
2. This method provides uniform wetting of the soil profile
3. It requires lower labor assistance
1. Requirement of relatively large water streams for the quick dispersal of water to decrease deep percolation losses at the upper end of the border strip.
2. a lot of wastage of water by deep percolation especially in coarse-textured soils.
(5) Furrow method;
1) This system is majorly used for irrigating vegetable fields furrows are simply inclined channels prepared by digging the soil
2) In row crops, furrows are made between the two crop ridges. Water is applied to the furrows and the top of the ridge is not directly wetted.
3) The furrows can be made along the slope when the level of the land is sloping gently up to three percent. When the slope exceeds three percent and is up to about 15 percent, the furrows are laid out on graded contours or as cross-slope furrows.
4)Water distribution can be controlled well to achieve uniform application and the consequent high efficiency.
5)The length of the furrows varies with the soil type, the slope and the quantity of water to be applied and may vary from 10 to 1,000 m in different situations.
6)The depth of the furrow should be such that water movement within the soil is predominantly horizontal into the plant root zone.
7) Crops, sensitive to the saturated soil conditions in the root zone and having subterranean storage tissue are generally irrigated by this method as a considerable number of roots and a part of stem remain above the saturated soil after the application of water in the furrows.
8) Crops with underground storage organs such as potato, sugar-beet, turmeric, ginger, colocasia, sweet potato, radish, and beet get sufficient space for the development of such organs above the wetting zone in the soil. Wide-spaced crops such as sugar cane, maize, and cotton are irrigated by this method.
9) Under conditions of limited water resources, alternate furrows are irrigated.
10)The watering zone of the furrow should be narrow; conversely, the ridges should be wide to provide enough underground space for the crop and to reduce the loss of irrigated water through evaporation.
11) In paired row planting furrows made between every second and third row are irrigated. The depth of water in the furrow should not be more than two-thirds of the furrow.
12) Water is applied either by breaching or with flexible siphons that connect the head ditch with the furrow. Individual furrows may be connected separately or a number of furrows may be connected by a common passage or cross-furrow made at the upper end or upper half of the furrows or at a convenient location.
13) If the field is quite level, water may be applied by the check and furrow method. In this method, after completion of the run of the water in the first furrow, the flow is continued to the second furrow through a breach in the ridge at the terminal end of the run. After the completion of the second furrow, the terminal end of the flow is continued to the third furrow through a breach. A number of furrows about 5 to 10) are irrigated with a single run of water that moves in a zig-zag way through furrows.
13) Small furrows known as corrugations are sometimes prepared in the case of the border strip method to increase the efficiency, the uniformity of flooding from irrigation and also to facilitate uniform and quick surface drainage required due to overflooding from irrigation or rainwater. This method can be adopted even for close-growing crops such as rape and mustard, groundnut chickpea, soybean, onion, garlic, cumin, anise, and coriander that are sown on rows on medium types of soil with rather uneven topography.
14) The cost of preparing furrows is more but in this method, water is applied uniformly. Because of the less open water surface, there is less evaporative loss from furrows, the risk of puddling clay soil is reduced, and men and machines can work in the field sooner after the end of the water application.
Due to separate water application zones, a considerable volume of soil is not compacted and soil aeration is not completely interrupted, weed infestation and the requirement of intercultural are proportionately less than in flooding method of irrigation.
1. It provides Fairly high irrigation application efficiency among all the surface irrigation methods
2. Furrows also serve as field drains in areas where heavy rainfall occurs
3. It moderately checks the evaporation losses
1. This method is not suitable in coarse-textured soils with high infiltration rates
2. More possibility of intra-furrow soil erosion
3. This method is labor-intensive