2012 Field Trial Results

In 2012 we conducted another series of on farm demonstration and research trials to assess the potential of inter-seeding cover crops in standing corn.

This complemented some of the research sites established on our research farm and were designed to gain experience with the technology under a broader range of field conditions. The demonstration projects were located in Crawford and Erie Counties in NW PA, in Bradford and Sullivan Counties in NE PA, and in Centre County in central PA.

The cover crops that were interseeded at most locations included Italian ryegrass and a mix of Italian ryegrass and clovers developed for us by a private seed company that we refer to as the Penn State mix. At several of the locations, we evaluated annual ryegrass and other species as well.

In general, weather conditions in the region consisted of a dry period from mid-June through mid-July with minimal precipitation at most locations, followed by good rainfall in late July, early August and early September. This resulted in stress full conditions for cover crop establishment but good conditions for cover crop growth in early September.

A brief synopsis of the farms and research projects is discussed below using the names of the farms as the site location.

Erie/Crawford County Demonstrations

We conducted two trials in Northwest PA with Bob Buhl in Erie County and Stephen Woods in Crawford County, in conjunction with extension educator Joel Hunter.

At the Erie County site conditions were dry for most of the season which is unusual for Erie County. Under these conditions, the mixes seeded with Crimson Clover seemed to persist well, while the grass establishment was very limited. At this site we had some difficulty penetrating the hard soil with the coulter without water in the tank of the interseeder. We filled the tank with water and then achieved good penetration.

At the Woods farm, we compared annual ryegrass to an Italian ryegrass/Crimson Clover blend. Here the grasses established well but the clover did not. At this farm, we found that planting into a manured rye cover crop residue made for a good seedbed for the cover crop, so this could be a long term goal. This field had long straight rows that were easy to interseed in as well. When we returned to the field in mid-October the ryegrass seeded strips were easy to identify.


Figure 1. Crimson clover establishment in early October at the Buhl farm.


Figure 2. Ryegrass establishment in early October at the Woods farm in Crawford County

Bradford/Sullivan County Research and Demonstrations

We conducted two trials in Northeast PA in Bradford and Sullivan County, in conjunction with extension educator Mark Madden.

On the Ron Kittle farm in Bradford County, a relatively dry summer limited establishment of both ryegrasses and clover.  At this site, a short residual herbicide program using Resolve gave good season long weed control in corn following alfalfa, which will be useful for future work. This field was part of our NESARE project where we compared a seed coating called 'Yellowjacket' to uncoated Italian ryegrasses and also a Italian ryegrass/clover mix. We did not find a significant effect from the 'Yellowjacket' seed treatment on establishment. Establishment of the Italian ryegrass was spotty, averaging about 2 plants/sq ft. across the field. There was variation across the field in establishment with some areas good and some sparse. In the clover/Italian ryegrass blend at this site, we saw low establishment of the clovers. The border rows here were planted to an annual ryegrass and these seemed to have much better establishment.

On the Wes Hottenstein farm in Sullivan County, we conducted a demonstration in conjunction with T.A. Seeds and Cover Crop Solutions with a variety of species, including oats, ryegrass, and tillage radish. We had success with a number of species, including tillage radish. This field was a high residue no-till field that was planted later in May. This field had a lower plant population than the Bradford site which could have contributed to the better establishment.

The ryegrass/clover blend established well as did the tillage radish and tillage radish/oat blend. The tillage radish here did not develop the large taproots as is typical in some other environments.


Figure 3. At the Kittle farm in Bradford County, establishment was slow and somewhat variable but there was good recovery in the fall.


Figure 4. An example of the radish establishment on the Hottenstein farm.

Centre County Research and Demonstrations

In Centre County, we had two SARE trials where we evaluated the potential of a seed treatment called “Yellow Jacket” on the establishment of an Italian Ryegrass and the Italian Ryegrass/Clover blend.

One was on the Corl farm near Pine Grove Mills and the second was on the Dan King farm near Milheim. At both of these sites, we also did not see an improvement with the seed treatment. Our conclusions are that we were not able to improve establishment with the seed treatment.

Establishment at both of these sites was variable in the field. In some areas of the field establishment was good while in others it was spotty. We also observed little clover in either field. We also did not see any of the sweet clover in either field. This was added to the mix to provide some potential hard seed that might germinate late in the year. During the late summer and fall, we had good recovery of the grass where had some establishment. At both of the farms we saw better stands in the border areas seeded to annual ryegrass. At the Corl farm, they were able to graze cattle on the ryegrass following corn harvest in mid-November.


Figure 5. Following harvest cattle grazed the established ryegrass at the Corl Farm.


Figure 6. Establishment was variable at the King Farm, but fall growth was good in some areas.

Potential Economic Benefits

During this year, we also began to realize the economic potential for a system with interseeding every year in continuous corn.

If an interseeded grass/clover crop could be terminated before planting corn and supply 50 pounds of N per acre and boost cost yields by 7% or 10 bushels per acre, then this could result in a benefit of $35/acre for the N and $70/acre for the additional yield at current prices. If two of the trips for sidedressing ($10/acre), spraying ($10/acre) or no-till cover crop seeding ($19/acre) could be eliminated for one trip with the interseeder ($25/acre) then this would result in an additional $14/acre savings. If realized, these benefits could total $119/acre with an interseeder-based corn cropping system. In some years, forage could be grazed and this would result in additional income. And at the same time, the field would have reduced erosion and runoff and more food for soil organisms and wildlife.


At several sites we had less than ideal establishment this year, but we did learn that there are some strategies that we could add that might increase the success rate under stressful conditions.

Because of the economic and environmental potential, we will be continuing to evaluate strategies for using the interseeder in the future. In 2013 we will be evaluating increased seeding rates, alternative species and varieties, and timing of establishment to improve success. We have also surveyed our cooperators for ideas on modifications to the interseeder to improve performance. If you are interested in learning more about the interseeder, contact Greg Roth at

Partial funding for the work reported here was provided by the USDA Sustainable Agriculture Research and Education Program.

Prepared by: Greg W. Roth, William S. Curran, Corey Dillon, Christian Houser and W.S Harkcom, Department of Plant Science.

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2012 Field Trial Results

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