Agricultural processes are the largest water consumers in many areas in the US. In Texas, for example, they account for 42% of the state’s total projected water use. The current model of water usage is not sustainable – 80% of water there comes from groundwater, and the existing groundwater supply is supposed to decrease by 18% by 2050. Furthermore, it takes a great deal of energy to power the current water processes. How do we tackle this problem? Farmers will only adopt a new solution if they don’t have to concede their main needs: convenience (via an automatic irrigation system), and high plant production (via constantly moisturized soil). There are several new processes in the design of fields and irrigation systems that minimize water wastage while continuing to cater to these farmers’ values.
Field design:
One interesting method I came across is called laser leveling, in which land-leveling equipment that contains lasers is used to shape the land in the manner that is best given the type of irrigation system used (level land for sprinkler systems and a uniform slope for furrow irrigation systems). Studies have shown that field unevenness and poor farm design leads to the loss of 20-25% of irrigation water during farming. Laser leveling therefore can make water use in irrigation much more efficient.
Furrow diking is another method that involves making small dams in the furrows so that precipitation or irrigation water can be captured and be slowly released into the soil, thereby decreasing runoff and increasing the amount of water sustained near the plants. In addition, conservation tillage – leaving most of the soil surface covered with crop stubble – is also an effective way to decrease wind and water erosion and increase soil moisture. Lastly, since there will always be some amount of runoff, it is important to have a tailwater capture system that reuses this runoff.
Irrigation system design:
In addition to better field design, more efficient irrigation systems are important as well. Many farmers currently use a sprinkler system or a furrow system, but studies have shown that drip irrigation is more efficient. With the drip process, small amounts of water are frequently emitted from underground tubing. Drip irrigation (shown in picture below) delivers water directly to the roots, which eliminates many of the problems of sprinklers, i.e. evaporation. Also, since moisture is concentrated near the roots, weed growth in the furrows is reduced.
If sprinkler or furrow systems are used, an improvement that can be made is to place the sprinklers lower to the ground and use less pressure in the water. This reduces evaporation and conserves energy. With furrows, a surge flow system can be used in which surges of water are applied intermittently instead of continuously, and the surges alternate between two different furrows. This allows for more uniform water distribution since water will always travel over wetter furrows to drier ones more quickly.
All of these agricultural methods conserve water and energy, while often increasing production and saving money. As water and energy prices rise, these efficient processes are becoming more and more necessary for farmers to adopt.
Sources:
http://www.twdb.state.tx.us/assistance/conservation/ConservationPublications/AgBrochure.pdf
http://dswcpunjab.gov.in/contents/data_folder/Laser_Level.htm
http://www.depts.ttu.edu/agriculturalsciences/news/?p=289
