Cooperative Extension Cover Crop Demonstrations in South-central Pennsylvania in 2008–2009

In the fall of 2008, agronomy extension educators in south central Pennsylvania planted a series of cover crop demonstration plots on cooperating farms. Rye and spring oats were planted as a standard for comparison. The other cover crops were forage radish, hairy vetch, crimson clover, annual ryegrass, Austrian winter pea and some mixtures comprised of these species.

These plots were seeded from September 11 to September 23. All were planted after corn silage harvest. These dates are later than normally recommended for some of the cover crops. However, we felt there was a need to test these at later dates. Farmers express interest in expanding use of legume cover crops beyond fields that can be planted earlier, such as after small grain harvest.

The purpose of this report is not to provide general information about cover crops as that is available from several good sources.

• Penn State Agronomy Guide
• Managing Cover Crops Profitably - SARE Cover Crop Book

Rather, this is to provide a visual tour of these plots through our photographs. Click on the name of the cover crop plot to see several photos from various fields and dates. (Note: Each slideshow starts automatically. Hover over the image to see the accompanying caption. Hover over the center of the image for the slideshow controls.)

• Cereal Rye
• Forage Radish and Oat Mix
• Spring Oats (var. Jerry)
• Hairy Vetch and Oat Mix
• Crimson Clover (var. Dixie)
• Crimson Clover and Annual Ryegrass Mix
• Annual Ryegrass (var. Marshall)
• Austrian Winter Pea
• Austrian Winter Pea/Annual Ryegrass
• Austrian Winter Pea/Triticale
• Austrian Winter Pea/Triticale/Annual Ryegrass

Spring Burndown Problems

When burning down legume cover crops in the spring, 2,4-D should be tank mixed with the glyphosate product you are using. Otherwise these types of cover crops will probably not be completely killed.

In this field (see far right), only glyphosate was applied. You can see that several weeks after burndown, the hairy vetch is injured but did not die. This field had to be resprayed to kill the hairy vetch.

The same problem occurred at this other demonstration plot (photo left). Notice that the strip of cereal rye to the left of the hairy vetch (center of picture) is dying. To the left of the rye is the strip of crimson clover. You can see it has recovered and its bright red flowers in bloom.

Although glyphosate alone will not effectively control hairy vetch, it does die in the strips from the physical contact from tires and row units, as seen in this photo (near right) from a farmers field in Cumberland County in 2005.

Observations About Winter-kill from Previous Demonstration Plots

We have had some plots in previous years that winterkilled. In one case the seeding date was much earlier than normally recommended. In another plot, manure was applied. We believe that the winterkill was related to having too much growth in the fall from either of these factors in combination with very favorable fall weather (2006) resulting in rank fall growth. The parts of the crimson clover and ryegrass plots that were grazed in the fall survived.

Crimson Clover

Annual Ryegrass

The fall grazing did not help hairy vetch survive any better than the non grazed area. It is possible that it may have been overgrazed or physically damaged by the cattle. Green areas are patches of chickweed or mustard.

Background Information

Thanks to the folks at King’s Agriseeds for providing the seed for this series of demonstration plots.