As water scarcity becomes an increasing threat across the United States, farms on smaller and larger scales are experiencing setbacks in food production. California, which is in the middle of a record breaking four-year drought, is still toying with different water conservation methods in their agricultural sector. Because California is a main producer in the fruit, vegetable, and tree nut industry, the drought has the potential to affect these supplies, fluctuating the economy of food production in the state. As the agricultural sector of California uses 40% of the state’s water, how do farmers work with irrigation? One of the main suggestions on lowering water use is seen in drip irrigation.
Drip irrigation is a sustainable farming method that uses pressured water flowing through pipes with emitter heads or small holes, which are placed directly at the base of a crop, as water drips out of the emitter head drop by drop over a period of time. Drip irrigation is seen as sustainable because it is measured in gallons per hour rather than gallons per minute, and reduces water evaporation and runoff. Drip irrigation is also known to be efficient because water is delivered directly to the topsoil above root systems over a longer period of time, so the roots intake water at a more uniform rate and are not susceptible to flooding or over-watering. Oregon State University has suggested an even more efficient method of drip irrigation, subsurface drip irrigation, where the pipes are buried underneath the soil to directly reach the roots of a crop and further reduce runoff and evaporation.
Compared to other means of irrigation across the United States, drip irrigation seems to conserve more water and produce more “crop per drop” than other methods, cutting water consumption on crops by as much as 50%. In the widely used spray or sprinkler irrigation seen commonly in the Midwest, agricultural lands are well watered but about 35% of this water is lost due to evaporation. In the Western U.S., because of federal subsidies and “use it or lose it” laws seen in Western water rights, farmers are encouraged to use flood irrigation, which loses a hefty amount of water to runoff.
Because of the controlled use of water and low cost of implementation associated with drip irrigation, it is a viable alternative for areas in the world that have a strict dry season, and areas that run on smaller economies. For example, in Haiti, there is a very defined wet and dry season. During the dry season when water is scarce, farmers would still be able to produce some amount of crops with minimal water usage. Because drip irrigation only requires a water pump, metal or plastic tubing, and a few adapters to connect the tubing to the pump, low-income communities could afford this method of irrigation even during the dry season, and could increase food security for their families and communities.
Although drip irrigation may seem like the end-all solution for water conservation in the agricultural sector, some have argued that is does not actually save water. In a 2008 study from the Proceedings of the National Academy of Sciences, it was found that sustainable irrigation techniques like drip irrigation may actually increase the amount of water consumed by crops. This is because when using drip irrigation over flood irrigation or sprinkler irrigation, a field of crops will use water more efficiently. Because of the efficient evapotranspiration of the crops, they will be at peak growing capacity, and will use just as much water as other means of irrigation. Although these plants may be consuming the same amount of water, because they are consuming it in a uniform rate which puts them at peak growing capacity, crop yields associated with drip irrigation are higher.
Image credits: http://www.csmonitor.com/World/Making-a-difference/Change-Agent/2011/1020/Cheap-drip-irrigation-could-transform-small-farms http://en.deere.co.th/en_TH/products/equipment/irrigation_and_water_management/drip_and_micro_irrigation_emission_devices/drip_tapes/t_tape/t_tape.page