Do you want to spend money on irrigation water only to see it run off the field, providing no benefit to your crop? Many farmers say they’re limited in how much water they can put on at one time, seeing runoff after less than an inch is applied.
What can be done to address runoff and improve efficiency in your irrigation system? Runoff isn’t the problem — it’s a symptom of poor water infiltration. The solution is to increase infiltration and your soil’s water-holding capacity.
It’s all about soil organic matter levels. Increasing soil organic matter by doing less tillage and adding cover crops will improve water-holding capacity. Every percent of soil organic matter in the top 6 inches has the potential to hold thousands of gallons of water per acre. What would an additional 1% soil organic matter mean to your crop and late-season water needs?
Irrigation water is also lost through evaporation. There are a wide variety of drop nozzles and high-efficiency nozzles that reduce evaporation loss. High-residue cropping systems that incorporate no-till and cover crops will result in keeping the soil surface covered, protecting it from evapotranspiration and leaving more water for your cash crop to use.
Determine irrigation efficiency
One tool that can help determine irrigation efficiency is a uniformity test. It shows where too little or too much water is being applied. Testing is accomplished by placing catch cans at specific distances under the whole system and running the system for a specified time to see how much water is actually applied. It’s possible for some parts of the system to underapply by 20% while some parts overapply by 20% — a 40% swing from the planned application rate.
Another tool for your irrigation toolbox is a soil moisture probe. Probes can help with scheduling applications based on current field conditions. They can also help identify if you’re getting the intended amount of water to the root zone where plants can use it. Is the water getting into the soil or running off?
These probes can provide real-time data accessible from your smartphone, tablet or computer, allowing you to monitor irrigation systems without making a field visit. There are different types of probes on the market, and producers should work with a reputable dealer to find the best ones for their operation and to ensure proper installation and calibration.
During the drought of 2012, USDA Natural Resources Conservation Service in Indiana worked with a farmer who said: “We have invested in irrigation over the years to prepare for summers like 2012. In a field that had not yet been converted to no-till and cover crops, we could only apply a half inch of water before it began to run off. Where we had three years of no-till and two years of cover crops, we could put over 2 inches of water on without runoff. … That field made 230 bushels per acre!”
The impact of improved irrigation efficiency is a positive return on dollars invested in not only an irrigation system but also a soil health system. Improve your irrigation efficiency by starting your soil health journey today.
Donovan is a district conservationist and Bailey is the state conservation agronomist with the Natural Resources Conservation Service in Indiana. They write on behalf of the Indiana Conservation Partnership.