Dairy farmers who have soil-erosion problems under alfalfa-corn rotations may want to watch results from a promising new system – intercropping corn and kura clover.

University of Wisconsin-Madison researchers found that they can produce a good corn crop after planting the corn into a herbicide-treated stand of kura clover, and still have the clover stand recover to full production the following year without replanting. The economics of the new system compare favorably with an alfalfa-corn rotation.

The research may be particularly important in hilly areas of the state, especially in western Wisconsin where soil erosion losses can be severe.

“Most dairy farmers grow a combination of grain and forages to balance rations,” says agronomist Ken Albrecht of the College of Agricultural and Life Sciences. “In Wisconsin that usually means alfalfa-corn rotations. But erosion with this rotation continues to threaten the soil”s long-term productivity and surface water quality.

“Problems with soil loss occur when farmers prepare fields for planting either corn or alfalfa. Once alfalfa becomes established, the soil is protected far better than at any other time during the alfalfa-corn rotation,” Albrecht says. “Conservation tillage would reduce soil losses during planting. However, most Wisconsin farmers haven”t adopted it for a variety of reasons. We”re looking for profitable alternative cropping systems that can provide the soil-conserving benefits of an established forage cover on a continuous basis.”

Albrecht and his graduate research assistant, Robert Zemenchik, began to consider living mulches – plants that can be grown with a main crop without reducing its yield. Others had tried alfalfa as a living mulch with corn and failed. Albrecht thought kura clover might be successful because of its unique characteristics.

Kura clover is relatively new to state farmers who have begun to plant it in hay fields and pastures. Kura clover lives much longer than alfalfa, regrows and spreads rapidly from rhizomes (underground stems), survives Wisconsin”s harshest winters, makes excellent feed and yields about 80 percent of a good alfalfa crop.

In a study at the UW-Madison”s Lancaster Agricultural Research Station, the agronomists planted corn hybrids in 1996 and 1997 no-till into kura clover that had been established in 1994. To make sure the kura clover wouldn”t provide too much competition for the corn, the researchers treated the kura clover with glyphosate herbicide to suppress it, to kill a 24-inch band, or to kill it all. In some plots they also added 50 pounds of nitrogen per acre.

“In general,” says Albrecht, “grain and silage yields were greatest where kura clover was completely killed. In 1996, corn grown in suppressed kura clover was as productive as that grown in killed kura. But in 1997 the best living mulch treatment yielded 14 percent less than corn grown in killed kura clover.” The cool spring and resulting slow start for corn in 1997 allowed suppressed kura clover to recover and compete with the corn early in the growing season, according to Albrecht.

Agronomy graduate student Palle Pedersen is currently working with Albrecht to identify strategies – including the use of herbicide-resistant corn hybrids – that will give growers more flexibility in controlling competition from kura clover. “The best of the 15 living-mulch treatments we evaluated in 1998 yielded more than 200 bushels per acre, only slightly less than the corn grown in killed kura clover,” Albrecht says.

The key to the system is to suppress the kura clover enough for corn to thrive, but also to get sufficient clover recovery by early autumn to provide ground cover over the winter and following spring. “Depending on the amount of suppression, we observed from 20 percent to 90 percent ground cover after silage or grain harvest,” Albrecht says.

In evaluating the kura clover yield available for grazing or hay the year after corn production, the researchers found the yield in 1998 was equal to the yield from kura clover left untreated the previous season; the yield in 1997 was slightly lower than the yield from kura clover left untreated the previous year. Albrecht believes that kura”s rapid recovery results from the clover”s production of rhizomes.

The agronomists worked with CALS economist Rick Klemme to determine that the band-killed and suppressed-plus-nitrogen treatments evaluated in 1996 and 1997 compared favorably with estimated profits from alfalfa-corn rotations over a 30-year period.

“Unusual growing conditions in 1997 may have lowered profit estimates for all the mulch systems we tested,” says Albrecht. “But it looks like we”ll need to find ways to consistently produce high yields of corn and recovering kura clover before the economics of this living-mulch system become substantially more attractive than alfalfa-corn.”

Still, Albrecht is encouraged by the kura clover-corn system. He is analyzing 1998 results from Lancaster and hopes to expand his research in 1999 to include tests at the Arlington Agricultural Research Station.

“If successful, this system wouldn”t need added nitrogen, would make weed control easier and reduce soil erosion,” he says. “Farmers would get a larger first harvest the year after corn and they”d be spared the costs of replanting.

“We”re looking for a system that will be good for farmers and good for the environment over the long haul. I think this one has promise.”