Friday, February 14, 2014

The Effectiveness Of Pulse Irrigation

By Eliza Mendoza


As the world population grows, so does the need for food. Conversely, the arable land reduces with time. This calls for increased use of irrigation and other farming methods that utilize small spaces for maximum production. Pulse irrigation is a system that when used with other systems helps manage water while producing healthy crops hence more food.

Used together with drip or even sprinkler systems, this system makes it possible to manage water usage effectively. It is scalable to whatever level one desires for maximum water saving features. It is applicable also with the low flow systems and the ultra low flow systems of irrigation.

For areas with very scarce water like in the deserts, this system has proven to be effective in saving water while satisfying the plants. The operation works by allowing water to passively flow into a reservoir at controlled rate. This builds pressure steadily till it reaches a predetermined level. The pressure then forces open the outlet valves and a pulse of water goes out.

The flow gradually lowers the pressure hence the valve closes again so that the reservoir can recharge again. The inflow is kept below the outlet flow therefore the cycle is maintained. A drip flow controller is used at the inlet managing the rate at which water flows into the reservoir therefore the timing.

Once set, this system can operate without any other input for long periods of time. This constant and frequent irrigation helps reduce water demand by the plant while also lowering water usage very efficiently. The plants are also protected from water stress due to the intermittent water supply to the soil.

To make this system work, strong magnets are used to keep the outlet valve closed. As the reservoir pressure overcomes the magnet strength, they are forced open and the top one goes up allowing water to flow. When the pressure reduces, the magnet lowers and sticks back in position and another cycle of recharging starts.

Using this on a sprinkler system is very effective for open farming. When seeds are germinating, one can use a frequency of 5 second sprinkling every minute for the first 2 weeks. This can then be adjusted to 8 hours sprinkling three times a week. This frequency is determined by plant water need, weather condition and the strength of the sun in that season.

The advantages of using this pulse irrigation system are numerous. When used for drip and sprinkler systems, there are no run off on if using heavy soil. In sandy soil, you have no leaching and water is not lost even though sand has low water retention capabilities. In hilly areas and shallow soil, water can still be applied efficiently without any run off. Temperature control can be achieved through evaporative cooling by use of the intermittent sprinkling and use of foggers. Given the very low discharge rate, growing plants in containers or greenhouse will require less space. It allows for the use of lower capacity pumps and smaller conduits hence reduced system costs in general.




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