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Sometimes referred to as flood irrigation, surface irrigation is an approach to irrigating farmland or gardens by simply allowing the water to flow into the area. Utilizing gravity in an efficient manner is essential to the process of any surface irrigation project. This particular means of irrigating land is the oldest approach known to humanity, and is still one of the most common.
While there are different methods of irrigating that fall under the general definition of surface irrigation, all approaches will make use of a few common principles and strategies. The water source will be located at a point near the top end of the area that will receive the flow of liquid. As the water descends into the garden area, it will be directed through furrows or allowed to puddle once it has reached the far end of the growing field. Once the area is irrigated to the satisfaction of the grower, the supply is shut off at the point of entry to the field, and the water is absorbed into the ground.
There are three forms of surface irrigation used for commercial and family owned farms. The level basin method is one of the more popular of all surface water irrigation strategies. With this method, the terrain of the garden area is more or less flat, with earth banks around the perimeter. Water is introduced into the basin quickly and allowed to stand as it is absorbed into the soil. It is possible to create a series of basins, and allow excess water to drain from one basin to the next in order to maximize the efficient use of the water.
Furrow irrigation is another popular approach to surface irrigation. This process involves the creation of furrows, or channels, that are located on each side of the rows of plants. Water is introduced at the top of each furrow and allowed to run to the end of the row. Moving the water through at a rapid speed will make it possible to ensure that the end of the row receives an amount of water that is comparable to the water that is absorbed at the front of the row.
One sub-group of furrow irrigation is known as surge irrigation. This method of surface water irrigation is similar to furrow irrigation, in that the water flow moves from the top of a row to the end. What is different with this surface irrigation system is that the water is released in spurts, rather than a single steady flow. The result is the establishment of a controlled pattern of wet and dry cycles that may be ideal for some types of plants.
The last class of surface irrigation is known as the border strip approach. An system of this kind integrates elements of both level basin and furrow irrigation, in that the earth borders are spaced closer together. This effectively creates thin channels that make the task of directing and controlling the flow of water a relatively easy job.
With all forms of surface irrigation, there is the danger of waterlogging the field, which may lead to crop loss. Monitoring and adjusting the approach used will often minimize this possibility. In addition, using lesser-known methods, such as surface drip irrigation, may be a better option in some cases.