Sometimes good research just backs up what farmers already suspect. Nine years of research at Mississippi State University's Delta Research and Extension Center in Stoneville reveal that using subsoiling with irrigation does not improve cotton yields enough to cover the expense of these practices.

Subsoiling, which uses a specially designed foot that moves underground, lifting and fracturing hardpan, “allows for better water and root penetration,” says H.C. Pringle, Mississippi Agricultural and Forestry Experiment Station associate ag engineer.

“This research started several years ago, when one of our agricultural engineers asked if conditions weren't conducive in the fall to do subsoiling, could we skip it for the year and just use irrigation? He wanted to know if yield would be lost under this scenario,” says Pringle.

Subsoiling is best done in fall when the ground is dry and hard. If rains keep machinery out of the fields during this window, fields that are subsoiled in spring may not benefit as much from the tillage.

“We found that the least expensive per-pound-of-lint method for cotton production was to subsoil in fall and not irrigate during the growing season,” Martin says.

Returns were maximized with either the irrigated, non-subsoiled or the non-irrigated, subsoiled environments.

“Lower returns occurred in the irrigated, subsoiled environment due to the higher costs and lack of yield increase,” Martin says.

He says most producers who don't have irrigation have been subsoiling for years. Those with irrigation have tended to use no-till or reduced tillage on their fields.

Because of these common practices, Martin says the research results were not surprising.

“It has always been suspected that you didn't need to use both practices, but it had never been quantified,” Martin says. “We found that if you don't already have irrigation, you're just as well off by using subsoiling only. If you already have the investment in irrigation, you don't need to subsoil.”

The full findings were published in the Journal of Cotton Science. More information is available online at http://journal.cotton.org.