Winter Cover Crop Experiment

SUMMARY
Aviva Maller, project coordinator, operates a 1-acre organic farm on land that’s been farmed organically for 10 years. Even though winter cover crops are considered an important part of organic farming, they’ve not been used on this parcel. Because Maller’s drip irrigation system is shut down during the winter, she sought to experiment with drought-tolerant cover crops to see which would work best in the arid climate of southwest Utah.

Maller planted three sections of her farm, each with different cover crops: crimson clover, Austrian winter peas and a mix of hairy vetch (85%) and winter rye (15%), crops chosen for their reputation as being drought tolerant. The Austrian winter peas germinated poorly, eliminating them as an option, but the other cover crops thrived, remaining green and robust through the winter despite only intermittent rains, although their health invited gophers.

OBJECTIVES
· Divide the farm into four sections, testing crimson clover, Austrian winter peas, a mixture of hairy vetch and winter rye and a control plot, with three replications of each plant or plant mix
· Record sowing dates and densities, germination dates, weather, irrigation schedule, weeding times, growth habits, estimated biomass grown, when and how each is incorporated into the soil and decomposition times
· Take soil samples in each plot to analyze soil fertility, pH, texture, salts, organic matter, nitrogen, micro-nutrients, etc

RESULTS
Maller prepared the ground for seeding by roto-tilling then hand raking. She broadcast the seeds by hand on Sept. 18, 2003, to give them ample time to establish before the first frost in early November. She roto-tilled again to cover the seed with soil and laid drip irrigation tubing on each bed to water the crops through November.

Temperatures in late September ranged from the high 80s to the low 50s, prompting the clover and vetch/rye mix to germinate quickly, in 10 to 12 days, both with even germination. However, the Austrian winter peas germinated poorly – she reported previous difficulties growing beans and peas on her ground – so she eliminated Austrian winter peas as a cover crop choice.

Meanwhile, the vetch/rye mix reached 8 inches high by mid November and the clover 5 inches high. In late November, cool weather curtailed growth, but both crops remained about the same height through the winter.

Maller found through the winter that soil under the cover crops retained better structure and texture than with bare ground.

She tilled the crops using a roto-tiller in late January, and an unusual warm spell helped decompose the organic matter. She notes that tilling the crops with a roto-tiller not only is difficult but it also does a poor job of breaking up stems and roots. On a bright note, Maller said this allowed her to observe the cover crop root systems, which she described as thick and fibrous, 6 to 8 inches long and equal in biomass to the above-ground plant structure.

She added that the cover crop needed no weeding and that the drip irrigation system, which worked well and required little labor, was needed to help the crops germinate.

“Overall,” Maller said, “I felt that this experiment was incredibly successful. I found a proper time, a proper method and a proper crop to use for a successful drought tolerant winter cover crop in my region of southwest Utah.

BENEFITS OR IMPACT ON AGRICULTURE
The cover crop improved the soil’s structure, texture and fertility. And establishing the crop was not labor intensive, especially in relation to the benefits to the soil.

“The system worked successfully,” said Maller, “and I will use it in the future.”

PRODUCERS ADOPTION
None reported.

REACTIONS FROM PRODUCERS
None reported.

RECOMMENDATIONS
In the future, Maller hopes to employ the services of a farmer with a tractor and tillage equipment to incorporate the cover crop into the soil.

OUTREACH
Vernon Parent, Washington County Extension educator, shared the results with farmers and ranchers in the Washington County area.