July 17, 2012 | Minda Berbeco

Over 1,000 heat records in the United States were broken over the past two months, with expectations of more to come throughout the summer (1). The intense weather has shriveled corn (2) and scorched soybeans (3). In response to the heat wave and associated drought, one reporter visiting a tree farm in Ohio quipped, “Orange Christmas trees are not exactly what comes to mind when thinking about the holiday season” (4). But the intense heat and lack of rain in the early summer has caused concern about massive crop failure this year (5), potentially making those orange Christmas trees a reality.

With extreme temperatures and drought, farmers have been forced to rely more heavily on irrigation systems. Unfortunately water, especially in the Western States where irrigation is most common (6), is becoming a limited resource (7). Agriculture accounts for 80-90% of water consumed in the United States (8) and irrigation needs will only grow as temperatures increase as a result of climate change (7).

Since water prices for farms are often subsidized (9), it has been argued that farmers (especially with larger farms), do not take water efficiency seriously (10, 11). Yet, over the past 20 years, the amount of irrigated land in the Western states has increased substantially, but the amount of water applied to these crops has decreased (8).

How is this possible? Are farmers simply reverting to growing cactuses? It turns out that better irrigation management and equipment can reduce water usage substantially, and more farmers are updating their systems to include these technologies.

Irrigation systems

Traditionally, farmers around the world have used gravity irrigation, which involves flooding fields or trenches with water. This is a simple technique, but it’s wasteful, and doesn’t distribute water evenly across the fields. In the past two decades, there has been a shift away from gravity irrigation to sprinkler and drip systems, which are more efficient, but require greater infrastructure and therefore can be more costly (12).

Sprinkler systems, not surprisingly, use sprinklers to distribute water. The benefit of a sprinkler system is that it is mobile, allowing farmers to move it into fields during irrigation and out of the way during harvest. Moreover, researchers at the Pacific Institute found that changing from flood irrigation to low energy precision sprinklers, where the water is released close to the ground, can increase water efficiency by almost 20% (9).

As sprinkler systems are typically not as efficient in hot and dry environments, drip irrigation has been gaining popularity in regions like the San Joaquin valley in California (13). These systems are made of aboveground plastic tubes that deposit water slowly (i.e. drip) directly to each plant. Similar to sprinkler systems, drip irrigation systems can be up to 20% more effective than flood irrigation (9).

Though most popular with perennial crops, drip irrigation can also be used successfully with annual crops to reduce water usage and fertilizer leaching, while increasing both yield and quality (14). Researchers at the Water Management Research Laboratory at the USDA, found that subsurface drip irrigation, which buries the tubing underground, increased water-use efficiency, while improving yield and quality in tomatoes, corn and cantaloupe. Moreover, they found that if farmers could prevent root penetration and damage from burying animals, the subsurface drip irrigation system was as effective after 9 years as when it was first installed (15).

Soil Moisture Management

In addition to changing the irrigation equipment, farmers can utilize technology to better manage their soil moisture. Though there have been many advances in soil moisture monitoring, dating all the way back to the 1930’s (16), a study on farmers in the Central Valley of California found that few farmers utilized these devices, relying more heavily on their own senses and plant stress to evaluate soil moisture (8). A shift to these monitoring methods could reduce water usage even further, as it would allow farmers to only irrigate when absolutely necessary.

For farms interested in utilizing technology to measure soil moisture, there are numerous options, from hand-held probes or permanent installations all the way to hiring irrigation scheduling services to come out weekly and irrigate as appropriate. In order to utilize these options though, farmers need to learn a little bit more about their soils. They’ll need to calculate the field capacity (maximum amount of water that can be kept in the soil), irrigation depth and the refill point (their target moisture level). With this information, they can even set up automatic irrigation systems that maintain a specific soil moisture level throughout the growing season.

Deficit Irrigation

Deficit Irrigation is another method of reducing water usage that has become more popular in orchards and vineyards, where quality is valued over yield. This type of irrigation involves intentionally applying water below the evapotranspiration rate throughout the season or at certain developmental stages in order to stress the plant. As this method has been shown to reduce yield, it is not as valuable for many vegetable crops. In orchards or vineyards, though, deficit irrigation can be a useful management technique, keeping trees smaller while increasing fruit size and quality, all of which increase profits (16).

Other considerations

Many farmers have expressed that cost associated with updating their irrigation systems is prohibitive (13). The price for switching from a flood irrigation system (which has little infrastructure) to a drip system can cost as much as $1,000/acre to install. However, because of other savings in fertilizers, water and labor costs, this initial investment can be paid back within 2 years (9). The 2008 Farm Bill, set to expire this Fall, included a 75% cost share program to help farmers install more efficient irrigation systems (17). As congress wrestles with the 2012 Farm Bill this year, hopefully there will be additional efforts to help farmers support these initiatives.

As the climate continues to change and extreme rain events become more common, farmers will need to rely on thoughtful and efficient irrigation to manage their crops. Though there are many options for farmers wanting to utilize more efficient irrigation, the upfront costs can be daunting. Water efficiency is not just a farm problem, it is a global problem that requires investment in time, money and research in order to create productive and sustainable farms, and food for the future.

Other Resources:

Graphic: Efficient Irrigation by system type for 17 Western States , 1994-2008, USDA http://www.ers.usda.gov/media/574349/irrigationandwater_use_chart_2.png

Agricultural Management Assistance: http://www.nrcs.usda.gov/wps/portal/nrcs/main/national/programs/financial/ama

Smart Farms Website: http://www.smart-farms.net/

Citations:

(1) Wilson C(2012) “Heat wave: 1,000+ records fall in USA in a week”  USA Today, June 26, 2012. http://www.usatoday.com/weather/news/story/2012-06-27/heat-records/55874718/1

(2) Davey M (2012) “Searing Sun and Drought Shrivel Corn in Midwest” New York Times, July 4, 2012. http://www.nytimes.com/2012/07/05/us/for-midwest-corn-crop-the-pressure-rises-like-the-heat.html

(3) Barrett R (2012) “Heat, drought taking a toll on Wisconsin crops” Milwaukee-Wisconsin Journal Sentinel, June 29, 2012. http://www.jsonline.com/business/farm30-e15utoj-160876465.html

(4) Baron J (2012) “Heat, lack of rain causing problems for local agricultural industry” Lancaster Eagle Gazette, June 27, 2012. http://www.lancastereaglegazette.com/article/20120627/NEWS01/206270304/Heat-lack-rain-causing-problems-local-agricultural-industry

(5) Amarnath N (2012) “Midwest Heat Wave Damages Crop Yields, Presses Food Prices” International Business Times, July 3, 2012. http://www.ibtimes.com/articles/359074/20120703/corn-wheat-soybeans-chicago-board-trade-u.htm

(6) Sands, R &W Paul (2011) Impacts of Higher Energy Prices on Agriculture and Rural Economies, ERR-123, U.S. Dept. of Agriculture, Econ. Res. Serv. August 2011. http://www.ers.usda.gov/media/118256/err123_1_.pdf

(7) Hall ND, Stuntz BB & RH Abrams (2008) Climate Change and Freshwater Resources. Natural Resources & Environment, 22(3): 30-35.  http://ic.ucsc.edu/~mloik/envs80b/FreshwaterResources.pdf

(8) USDA-ERS(2012) “USDA ERS – Irrigation & Water Use  Background” June 12, 2012 http://www.ers.usda.gov/topics/farm-practices-management/irrigation-water-use/background.aspx

(9) Cooley H, Christian-Smith J & PH Gleick (2008) More with Less: agricultural water conservation and efficiency in California.  Pacific Institute. http://www.pacinst.org/reports/more_with_less_delta/more_with_less.pdf

(10) Martin G (2004) “CALIFORNIA / Big farms found to get most water subsidies / Cost often a fraction of what residents pay in L.A. region” December 15, 2004 http://www.sfgate.com/bayarea/article/CALIFORNIA-Big-farms-found-to-get-most-water-2663663.php

(11) Environmental Working Group (2002) California Water Subsidies: Executive Summary.  http://archive.ewg.org/reports/Watersubsidies/execsumm.php

(12) Colby BG & GB Frisvold (2011) Adaptation and Resilience: The Economics of Climate, Water, and Energy Challenges in the American Southwest (RFF Press Water Policy Series). Earthscan LLC, Washington DC, Chapter 9.

(13) Agricultural Water Management Council and. California Farm Water Coalition (2010) Irrigation Practices and Influencers Survey Findings San Joaquin Valley Agricultural Water Management Council and California Farm Water Coalition.   http://www.agwatercouncil.org/08312010.pdf

(14) Sharmasarkar FC, Sharmasarkar S, Miller SD, Vance GF & R Zhang  (2001) Assessment of drip and food irrigation on water and fertilizer use efficiencies for sugarbeets. Agricultural Water Management 46, 241-251. http://elmu.umm.ac.id/file.php/1/jurnal/A/Agricultural%20Water%20Management/Vol46.Issue3.2001/1577.pdf

(15) Ayars JE, Phene CJ, Hutmacher RB, Davis KR, Schoneman RA, Vaila SS & RM Mead (1999) Subsurface drip irrigation of row crops: a review of 15 years of research at the Water Management Research Laboratory.  Agricultural Water Management, 42:1-27. http://naldc.nal.usda.gov/download/22786/PDF

(16) Fereres E, Goldhamer DA & LR Parsons (2003) Irrigation Water Management of Horticultural crops.  HortScience 38(5):1036-1042. http//www.crec.ifas.ufl.edu/academics/faculty/parsons/PDF/280503hs.pdf

(17) USDA-NRCS (2008)  Fact Sheet: Agricultural Management Assistance Program http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1042019.pdf