Water conservation in agriculture

Vew rom the corn of the irrigator above

Agricultural water use

Minnesota has over a half million irrigated acres of farmland. About 81.5 billion gallons of water are applied annually. In some areas of the state, the recent upward trend of water use increases the strain on water supplies. As much as 90 percent of this water in Minnesota comes from groundwater. Extraction of water often exceeds its natural replacement by rain and snow melt. Effective water conservation ensures that Minnesota agriculture can continue growing crops well into the future. 

Line graph of an upward trend of water usage in Minnesota from 1994–2017

As of 2017, Minnesota had more than 68,800 operational farms, generating more than 18 billion dollars in agricultural products. A growing portion of these farms rely irrigation; about 95 billion gallons were used in 2017. The recent upward trend of water use increases the strain on water supplies, threatening the sustained operation of Minnesota farms. As much as 90 percent of this water in Minnesota comes from groundwater. The aquifers where groundwater is extracted usually replenish slower than the rate at which water is used. Effective water conservation ensures that Minnesotan agriculture can continue growing crops decades into the future.

Opportunities for conservation

Conservation methods can reduce agricultural water use while effectively irrigating crops. A number of factors affect irrigation efficiency, such as soil type, crop type, temperature and evaporation. Sprinkler design, such as precision or micro irrigation can improve distribution, effectiveness and efficiency. Drip irrigation applies water directly to plant roots to minimize evaporation. More advanced irrigation scheduling techniques can prevent salinity buildup in soils by reducing the amount of water applied to fields. 

For more information about irrigation scheduling and irrigation management strategies, see Irrigation, the University of Minnesota

The electrical costs of pumping water are high, so conserving water also reduces energy costs. Conserving water ensures a more sustainable and stable water supply in the future and reduces energy costs in the present.

Using water more efficiently reduces runoff and deep percolation that washes pesticides and fertilizers into drainage systems and aquifers.

The Minnesota Agricultural Water Quality Certification Program (MAWQCP) provides a certification program in water quality to help protect surrounding watersheds, see the MAWQCP website.

Sprinkler irrigation

Central Pivot Irrigation is the most common form of sprinkler irrigation in Minnesota. Efficient drip nozzles reduce high water loss due to wind and evaporation. Larger sprinkler heads that irrigate multiple furrows at once are susceptible to water loss. Pivot sprinklers with more sprinkler heads spaced closer together, and those that apply water closer to roots, reduce the water loss, have higher efficiency and increased water savings.

Low Energy Precision Application (LEPA) is a high efficiency method of water application. Using pivot or linear move structures, LEPA applies water in furrows near plant roots, instead of into the canopy of crops. It uses low pressure water application, reducing the fine mist of high pressure sprinklers that is susceptible to water loss from evaporation. Close spacing (often around 30 inches) ensures adequate water application at a high rate of efficiency. This reduces water loss from evaporation or wind drift and results in greater water efficiency.

Micro irrigation

Micro irrigation is the most consistently efficient method of irrigation available. These methods involve frequent, low-pressure application of water near plant roots. This irrigation method can lead to:

  • Higher crop yields
  • Enhanced water penetration in all kinds of soils
  • Reduced weed growth

The high cost of installation makes the micro irrigation techniques more cost effective for high value crops such as fruits or vegetables, especially if these irrigation pipes are located beneath the soil surface for minimal evaporation. Despite the large investment needed, this irrigation method is highly efficient and sustainable. Some Minnesota farmers now use drip irrigation for traditional row crops to great success.

For more information see: Minnesota Irrigation and Water Management

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