New technologies are increasingly available for improving irrigation, but every growing season does not have the potential profitability to support purchasing upgrades. For conservation-conscious producers looking to improve their irrigation efficiency, switching up four on-farm practices could make a big difference in a tight margin scenario.

Increased infiltration

Water works best when it can work its way into the ground for maximum contact with a cash crop’s roots. Improving water infiltration through practices like conservation tillage, subsoiling, residue management and ground leveling can help producers make the most of money spent on irrigation.

“Silt loam soil seems to be especially susceptible, much more so than heavy clay soils that will crack so there's no problem with infiltration on them in the middle of the summer,” said Mississippi Water Resources Research Institute assistant professor Dave Spencer. “Silt loam soils, because of the different texture and the different properties that they have combined, with the fact we’re no longer subsoiling to break up that compaction, can have bigger issues with infiltration.

Timely terminations

More isn’t always better, especially in water applied on-field through irrigation. Research conducted at the MWRRI showed that irrigation applied too early in corn could be yield-limiting, while continuing to irrigate a crop after it reaches maturity can cost producers as much as $5-$10 an acre in unnecessary water usage, as well as potentially delay harvest.

“As the crop reaches maturity, it’s using less and less water,” said MWRRI assistant professor Dave Spencer. “Deciding a termination depends on knowing how much water your crop is using versus how much it's got in the soil. If you know that, then you can cut out those irrigations that might not be necessary.”

In addition to scouting fields for signs of maturity, Extension researchers also regularly release termination guidelines to assist producers in knowing when to start and stop irrigation events.

“All of the irrigation specialists across the Midsouth, I think they've done a really good job over the last 10 years of establishing guidelines for when to initiate or terminate irrigations largely based on sensor technology,” said MWRRI director Jason Krutz. “But if sensor technology is not in place, the guidelines are still there for at least termination because for corn, soybeans and cotton, particularly, when I was walking fields a lot more regularly 10 years ago, we were sending irrigation events down that were not beyond a shadow of a doubt, necessary.”

Early planting

“If you can plant it early, you're going to catch more spring rains and you're going to have to irrigate less,” Krutz said. “That's a really, really big deal especially in a crop, like soybean or corn.”

Early planting doesn’t necessarily mean planting during less-than-ideal conditions either. Aiming for the earliest recommended planting dates can help simplify the rest of the growing season.

“State Extension offices have optimum planting dates for crops that you can follow,” Krutz said. “We're not talking about planting in January, we're talking about planting on the early side of those optimal windows.”

Variety selection 

In addition to early planting, an earlier maturing variety can also help limit irrigation events and ultimately water usage during the growing season.

“We looked at earlier maturing soybeans, so we did experiments like looking at maturity group 4s and 3s at different planting dates,” Krutz said. “The data says that in these earlier planting windows for us, we often receive more rainfall and they require less irrigations.”

Krutz said those plantings often yielded as well as maturity group 5 soybeans and were able to be removed from the field before the threat of late-season inclement weather.

“Go with what works well for your soil type on your farm,” Krutz said. “Producers ought to be doing their own experiments, putting in some variety strip trials to find out what's their best variety. Getting the right high yielding soybean on the right acreage planted at the right time, that should be the best water use efficiency for the crop.”

Variety selection is equally important in corn, where research has shown that traditional Midsouth corn varieties could out-perform some drought-tolerant varieties from a yield standpoint.

“The corn hybrids we traditionally planted in the Midsouth, in those early planting windows provided us the best water use efficiency for corn even over some of the lines that were supposed to be more drought tolerant,” Krutz said. “It looks like the best water use was to go with a high yielding corn variety at an optimal planting window ahead of sound irrigation practices.”