East Idaho grower tests winter clover as cover crop

Southeast Idaho grower Rob Giesbrecht walks through his field where a new clover variety is being seeded directly into wheat stubble. He's testing the clover as a winter cover crop option with a deep tap root and high nitrogen fixation potential.

AMERICAN FALLS, Idaho — A local farmer is testing a new species of clover, bred to enhance pasture land, as a unique cover crop option for his region capable of fixing nitrogen throughout winter while mellowing compacted soil.

Pleasant Valley grower Rob Giesbrecht directly seeded FIXatioN Balansa clover into 150 acres of wheat stubble on Aug. 12, spreading it with fertilizer applied to support residue decomposition and following with a roller.

Cover crops are planted solely for soil health benefits, such as building organic matter, preventing erosion, breaking up soil compaction, nitrogen fixation and biofumigation. In southeast Idaho, where many plant species aren’t adapted for the harsh winters, growers typically plant cover crops immediately following harvest and incorporate them into their soil in late October.

FIXatioN clover, however, tolerates extreme cold, produces a deep taproot and has fixed up to 120 pounds of nitrogen per acre in trials. Given its cold hardiness, Giesbrecht expects the clover will continue fixing nitrogen throughout the winter, maintaining roots in the soil to prevent erosion until he discs it into his soil during spring. The deep roots should also provide conduits for soil-moisture penetration.

Some area growers have tried Austrian peas as a winter cover crop to fix nitrogen, but Giesbrecht notes peas lack clover’s deep taproot.

“I don’t know another cover crop that has deep taproots like that and will create nitrogen like that in the time I have,” Giesbrecht said.

Giesbrecht intends to continue planting oilseed radish and mustard after harvest, working them into his soil in late October, for the biofumigation benefits, adding the clover provides one more tool for his farm.

“The seed is going to cost me around $20 per acre,” Giesbrecht said. “If it does what it says, it will save me $55 per acre in nitrogen, and I’ll also be ahead on organic matter.”

Giesbrecht has sold some of the seed to ranchers in several states as a dealer for Grassland Oregon, which released FIXatioN clover two years ago.

Don Baune, a partner with Salem-based Grassland Oregon, said the variety has won over farmers as a winter cover crop in the Midwest and can survive in temperatures as low as minus 10 degrees. He said it fixes about double the nitrogen per acre as crimson clover, on of the most popular nitrogen-fixing clover varieties, and also works well as a dairy silage crop.

Baune said FIXatioN clover was developed through conventional breeding, derived from a few clover plants in research plots that somehow survived an especially cold Oregon winter.

Baune envisions it will also prove to be an important nitrogen source for organic producers.

Doug Ruff, another Pleasant Valley grower, has never planted a winter cover crop and will be interested in Giesbrecht’s results. Ruff has experimented with clover and oilseed radish cover crop blends, discing them into his soil in October.

“We’ve got such low organic matter. (Cover crops) really help build the soil back up,” Ruff said. “I know the more you can keep your ground active, the better it is.”

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