Because of agriculture’s high-water use, our farmers and ranchers are always questioned about our efficiencies when applying water to our fields. We might try to remember if we eat and wear clothes, you and I are the ultimate water users. If we want food on our tables and clothes on our backs, agriculture must continue using water.
And by the way, we are so glad you asked about our water use efficiencies! Yesterday's Bureau of Reclamation water shortage Tier One declaration makes this water technology article that much more important.
We’ve put the breakout of our main technology advances in an outline form and embedded the Rosie on the House show segment that talks about Arizona agriculture’s water technology advances at the end of the article.
- Arizona agriculture is an extremely efficient user of water, and farmers have skin in the game when it comes to water use efficiency
- There is no silver bullet to saving water: the best method of irrigation depends on a variety of factors including soil type, region of the state and more.
- Technology (both existing and yet to exist) will play a key role in saving water while keeping farms in business
- Over the last three decades, agricultural water withdrawals have fallen by 35% in Arizona (urban withdrawals have increased by 68%)
- In 2013 alone:
- Growers of all crops spent $53.3 million on new irrigation-related equipment, facilities, land improvements, and technology
- That’s an average spending of $151 per acre, $42,939 per farm. Central Arizona Project users have invested $3,600 per acre!
- $12.2 million of that money was for the primary purpose of conserving water
- In small grain production in Arizona, water applied annually per acre has fallen by 10% over the last 30 years.
- In cotton production in Arizona, water applied annually per acre has fallen by 8% over the last 30 years. The water footprint of cotton production (the amount of water used to make one bale of cotton) has fallen by 19%.
- Drip: uses low-volume, low-pressure water emitters to deliver a predetermined amount of water to a precise location.
- Uniform water distribution
- Very little loss to evaporation
- Very controlled and precise: only as much as you want, exactly where you want it
- Can save up to 40% when compared to flood irrigation
- Best on heavier soils; can work fine on lighter soils (sandy loam), but water moves laterally better in heavier soil. Heavier soil also usually has a better holding capacity, meaning the water is there long enough to be utilized by the plant before it continues percolating down
- Expensive! Installation and maintenance can cost upwards of $1200 per acre.
- Sprinkler: pressurized water delivered on top of the plant
- Uniform and precise water distribution, similar to drip irrigation
- Can save up to 20-30% when compared to flood irrigation
- Good for produce where there are food safety concerns with standing water, and where a higher volume of water is needed to germinate seeds.
- Need the right soil slope and type
- Cost to repair and maintain
- Soil Monitors
- Data loggers and sensors can be used to gather information about soil moisture and weather conditions that can then be incorporated into irrigation scheduling.
- Proper scheduling allows the highest amount of water to be absorbed by crops and additional watering to automatically shut down when the desired soil moisture level has been reached--avoiding overwatering, and conserving water while sustaining crop growth and development.
- Though often maligned, flood irrigation is actually one of the most efficient methods of irrigation around!
- How farmers make it as efficient as possible:
- Laser Leveling of Fields: leads to uniform application of water – same amount across the entire field
- Tailwater Pump-back Systems: water that did not soak into the soil before reaching the end of the field during an irrigation run is collected and reused through a pump-back system.
- Replenishes groundwater through return flows – some of that water goes back into the ground
- Leaches salts out of the ground that would otherwise build up and make plant growth impossible
- Criticisms of flood irrigation often center on evaporation rates, but those are mitigated because of how quickly the water is absorbed back into the field.
- One farmer gave us the example of an alfalfa field. In the summer, it only has standing water on it for about 8 hours per month (compare that to a swimming pool!)
- The Norman Borlaug Era beginning in the 1940s really brought seed improvement technology to the forefront
- Despite regulatory hurdles, the need for public perception shifts around biotech
- Biotech crops continue to move the needle forward with efforts for more genetic traits designed around what benefits the end consumer.
- Improved seed technology developed drought-resistant seed, reduced pesticide use, created sturdier seeds and more.
- While the public is often afraid of modified seeds (genetically modified), nature and farmers have been modifying crops for thousands of years.
Low/No-Till and Crop Rotation
- No-till does two things: prevents soil disturbance and allows for plants to grow and create a soil cover (fancy way of saying “weeds”)
- This means that the soil contains more organic matter – plant residue
- Less soil disruption means soil can sequester more carbon
- Lowers soil temps
- Improves moisture retention
- Crop rotation is growing different crops on a multi-year cycle, so that crops that take more out of the soil are rotate with crops that retain and fixate nutrients into the soil.
- For example, “The Rayner Method” is a combination of wheat, cotton, and alfalfa over a six-year cycle. It’s water savings include a decrease from 42” to 26” inches on a cotton crop.
- In Yuma, farmers have transitioned from year-round crops to a wheat/vegetable rotation. Wheat matures late in spring, before the hot summer. Vegetables grow in the winter, also less water demand. This has reduced water use per acre by 24-56% -- and put Yuma on the map as the lettuce capital of the world