Building on past work done by researchers in other states and incorporating relevant technology, we propose to
explore corn silage production systems that employ perennial living mulches (PLM) to protect surface water and
improve soil quality. Our goal is to increase the percent of in-season and post-harvest vegetative cover of corn
silage fields in the Northeast.
Questions we wish to answer include:
1) to what extent (if any) do PLM impact corn silage yield an area of the Northeast where rainfall tends to be
consistently higher and better distributed during the growing season than other regions of the U.S.
2) at critical times of year do PLM cover the soil significantly more than approaches (i.e. cereal rye planted after
corn harvest) currently used?; and
3) does current locally available technology allow for efficient establishment and management of PLM systems?
Our objectives are to:
1) describe the impact of PLM on corn silage yield compared to two controls;
2)describe the functionality (i.e., ability to cover the soil) of PLM compared to two controls; and
3) determine if locally available technology is sufficient for establishing and managing PLM in corn silage.
Research on living mulch systems has been conducted since the 1975, with soil stability, nutrient scavenging, and biological nitrogen fixation being primary drivers. Other benefits cited include: increased soil quality; reduced soil losses; weed suppression; and pest (insect, weed, disease) management via competition, obstruction, and/or promotion of beneficial insects. Systems in which living mulches can fit include vineyards, orchards, and row- and
vegetable crop production fields.
The most visible sets of research on the subject of living mulches in corn cropping systems have been generated by Nathan Hartwig (Penn State – emeritus), Ken Albrecht (University of Wisconsin), and Nick Hill (University of Georgia).
Challenges that those researching living mulches are trying to overcome include:
1. The living mulch becoming excessively competitive with the crop. Assuming that an appropriate PLM species is chosen and is adequately suppressed to prevent light competition, water competition/use is the biggest challenge, especially in dry areas/years. A kura clover living mulch had a minimal impact on corn yield in years where soil moisture was adequate leading up to canopy closure, but detrimental to yield in years where rainfall leading up to canopy closure was deficient.
2. Establishment or persistence of the living mulch species. While the persistence and glyphosate tolerance crownvetch and kura clover seem to be excellent PLM candidates, they can be difficult and slow to establish. While white clover establishes relatively quickly and thrives Northern regions, winter stolon injury is often severe, resulting in slow spring recovery. All of these challenges can be managed to varying degrees, depending on the environment.
3. Suppressing the living mulch without killing it. Albrecht, Hartwig, and Hill have each spent considerable time developing protocols that can reliably suppress the living mulch while the corn is being established, yet that without reducing the functionality or survival of the living mulch. Albrecht (et al.), Hartwig, and Hill have each developed herbicide suppression + no-till corn planting protocols that are effective for suppressing PLM in their
Even with perfectly balanced suppression of the living mulch corn production system, water competition can limit corn yield. In Georgia’s climate, this would happen every year, so Nick Hill’s research is conducted under irrigation. In Wisconsin, heat/drought problems are occasional and, given that few acres are irrigated in Wisconsin, yields can be significantly reduced in dry years.
Rainfall in Northeast and Central Vermont is typically abundant and regular during the growing season. Given these conditions and the existing living mulch suppression approaches developed by Albrecht, Hartwig, and Hill, we believe that one or both of these systems will be adaptable to high-rainfall areas of the Northeast. With locally available band-spraying and no-till technology, we believe that these systems will be adoptable by many farmers.
2017 Carson Farm Strip Trial – On May 4, 2017, we seeded a four replicated strip trial (20′ by 40′ per plot) of four perennial legumes (crownvetch, birdsfoot trefoil, white clover and kura clover) at the Carson Farm in Newberry, VT. We used a walk behind Carter small plot seeder to plant each plot. The site was part of a corn field that had been tilled the previous fall. The intent was to get the stand established and no-till corn into the strips in 2018. Plot were clipped twice during the summer to suppress weeds.
2017 Stocking Farm Field Demonstration – In May of 2017, Steve Stocking and Dan Hudson planted a 5 acre field to corn to be harvested for silage with an underseeding of Kura Clover. The corn was planted with a four row planter and the kura clover was then drilled in with a no-till seeder on the same day. The corn was a Clearfield hybrid so that Pursuit herbicide could be applied since Kura clover is tolerant of this product. Pursuit was applied in June.
2018 Stocking Establishment Trial – After the failures in 2017, we focused on a different approach to establishing perennial legumes as an under story in corn grown for silage. First, we wanted to used cover crops, methods and products that are readily available to farmers and avoid having to use any special hybrids or products. Our focus was using a Roundup Ready corn hybrid with only glyphosate as our weed control. Both of these are common practices that conventional farmers use; therefore, we thought if this method works, we’d have a better time getting farmers to try it.
The corn was grown for silage and planted on May 14th at a population target of 32,000 plants per acre. Treatments included five perennial legumes interseeded (broadcast followed by light raking) in combination with four seeding time/herbicide treatments. Cover crops included alfalfa, kura clover, subterranean clover, white clover, red clover and a control of no cover crop. We had three cover crop planting times: 1) at time of corn planted, May 15, using no herbicide, 2) when the corn was in 2 leaf stage, May 30 (using glyphosate to kill any emerged weeds), and 3) when the corn was at the 4 leaf stage, June 20 (again using glyphosate to kill emerged weeds). An additional fourth treatment included planting at the 4 L stage but using a repeated application of glyphosate (once when corn was at 2L and again when corn was at 4L).
2017 Carson Farm Strip Trial – Due to a severe weed infestation, the plots were unsuccessful in effectively establishing enough to continue the next year’s phase. The farmer decided not to continue the project with a reseeding.
2017 Stocking Farm Field Demonstration – The Pursuit herbicide was only partially effective in weed control and the kura clover was fairly sparse in germination and establishment. Also, the farmer felt that the extra weeds significantly hurt his yield. By the end of August, there were sections of the field with some Kura clover in the under story; however, by the time the corn was harvested, there was very little visible clover. The farmer decided not to continue this demonstration field the next year since it would have required another Clearflield hybrid and the same herbicide both of which he was disappointed in. One of the challenges was that by being limited to the Clearfield line of corn hybrids, Steve was really limited in finding the best suited hybrid for his conditions. The other challenge was the limited weed control with only using the one herbicide product.
2018 Stocking Establishment Trial –
Legume germination and early establishment was poor across all three seeding times. It was very dry in June and July preventing the germination of legume seed and/or death of stressed seedlings. Overall, the alfalfa germinated the best followed by red clover and white clover. There was very little kura clover or subterranean clover that germinated regardless of planting time. By June 20, the weeds in the “Corn Planting” time treatment strips were well in advance and competing heavily with any legume seedlings as well as competing with the corn plants. By the end of the season, there were hardly any legumes present in this treatment. This was not totally surprising since we knew there was no herbicide options for this treatment.
On May 30 during the 2-leaf seeding and on June 20 when seeding the 4-leaf treatments, alfalfa had the most seedlings of all the legumes.
Weed control – As expected, there was extremely poor weed control with the CP treatment since no herbicide was applied at all. A one-time application of glyphosate at the two-leaf corn stage provided about 50% to 70% control by the end of the season. However, the 2X applications resulted in good to excellent season long control.
Corn Yield – Due to limited time and labor, only the 1X and 2X glyphosate applications of the alfalfa plots of the 4 L seeding time treatments were evaluated for plant population and yield (Table 2). The 2X plots had about 1.7 t/a greater yield compared to the 1x significant at the 10% level of probability. Although yields were not collected for the CP and 2L treatments, corn plants in the CP plots were visabley shorter compared to the 4L plots and were likely to have had a significantly lower yield considering the level of weeds in those plots.
Summary – Legume establishment was disappointing in this study most likely due to extremely dry conditions and a high corn population. However, these findings suggest that glyphosate (a non-soil residual herbicide) applied at the 2 to 3 leaf stage followed by a second application at the 4 to 5 leaf stage could potentially be utilized to adequately control weeds allowing the interseeding of cover crops without the risk of herbicide residual injury nor impacting corn silage yields. However, this need further investigation.
Education & Outreach Activities and Participation Summary
August 4, 2018 – A Field Day sponsored by the White River Conservation District was held at Birch Meadow Farm (Steve Stocking) in Fairlee, VT to highlight various conversation practices including no-till corn, no-till alfalfa, and cover crops. We also were able to show and discuss our Living Mulch Establishment trial. There were approximately 14 farmers and four agriculture service providers that attended.
October 25, 2018 – a tour as part of a New England Ag Service Provider In-Service stopped by Birch Meadow farm where we showed and discussed the Living Mulch Establishment trial. There were approximately 8 that attended. A summary of the project results was handed out.
The cooperating farmers have learned the limitations of establishing cover crops as an under seeding in corn.
To be completed in final report