Establishing Cover Crops at Time of Corn Planting: Determining Soil - Water Quality Benefits

Establishing Cover Crops at Time of Corn Planting: Determining Soil - Water Quality Benefits

Summary

Establishing cover crops at time of corn planting gives farmers in the Northeast the possibility of establishing legumes and grasses which are not possible following corn harvest. The establishment of cover crops earlier in the season allows for more growth and nutrient uptake in the fall compared to cereal grains planted following corn silage harvest in October. This system provides the farmers another time within their operation to establish cover crops. This system does not rely on cultivation for seedbed preparation.

Objectives/Performance Targets

The objective of our study was to:

1) Investigate the establishment of cover crops at time of silage corn planting using herbicides to manage both the weeds and the cover crop.

2) Investigate the interactions between different herbicides, application timing, cover crop species and seeding rates.

3) Determine and quantify soil and water quality benefits.

Accomplishments/Milestones

Outreach continues to be a strong component of the work, with 15 meetings and demonstrations conducted with approximately 422 in attendance. Information was requested and sent out via e-mail to eight consultants or agency personnel outside of the work area. A PowerPoint presentation, poster, and a one-page instruction sheet was created and used during the meetings to inform farmers and agency personnel about the technique and the project. Articles were written in SWCD and Cooperative extension newsletters as well as in two newspapers. An article describing the project was put on the National Plant Materials web site http://plant-materials.nrcs.usda.gov. A demonstration was again established at the Empire Farm Days site in Seneca Falls, New York. One poster was presented at the National SWCS meeting in 2002. Agency people have been involved in establishing demonstrations with an extension agent in Cumberland County, Pennsylvania, establishing two trials on his own and four projects were conducted in Vermont with the St. Johnsbury Soil And Water Conservation District (SWCD) with assistance from the University of Vermont Cooperative Extension. Several NRCS and extension agents in New York and Pennsylvania have assisted in data collection and have attended field demonstrations.

In 2002 we worked with 28 farmers and four research facilities setting up demonstrations and or trials at 22 sites. Due to poor overall corn performance from drought conditions and other issues. not all sites were measured for yield. A study was conducted at four sites evaluating two seeding rates of alfalfa, red clover, white clover, and annual and perennial ryegrasses comparing corn yield and percent cover. A herbicide trial was conducted at Big Flats evaluating eight different herbicide treatments with seven species of cover crops. The soil quality experiment continued for the second year which will compare 3 species of cover crops red clover, alfalfa, and annual ryegrass following four years of cover cropping. The annual ryegrass/corn plots are established and compared with and without tillage.

Impacts and Contributions/Outcomes

When evaluating the effects of different cover crop seeding rates on corn yields, the difference in corn yields appear correlated with percent cover of the cover crops when measured in the fall. In cases where there was little difference in corn yields between cover crop seeding rates there was also not much difference in the percent cover. The red and white clovers had the most difference between percent covers and corn yield for the two different seeding rates. For red clover, the percent cover in the fall was 60% vs 70% for the low and high rates with 16.4 vs 13.5 t/ac of silage compared with 15.6 t/ac for the control. For white clover, the percent cover was 72 vs 82% with 16.2 vs 14.1 t/ac silage with 16.3 t/ac for the control. The white clover does have a stoloniferous rooting system so some of the cover in the low rate could have been made up by this spreading habit later in the season. White clover can be very competitive at 10 lbs/ac; lower rates of white clover or a mixture of red and white clover should be investigated. Due to the tolerance of the alfalfa to many of the herbicides used in this program and its high water use, it would be beneficial to reduce the alfalfa seeding rate even more or to include an herbicide like Accent which would suppress the alfalfa. A mixture (total 8 lbs/ac) of alfalfa with red clover would reduce seeding costs, insure good cover, and derive some of the benefits of the alfalfa tap root, while being less competitive than alfalfa alone. The alfalfa and annual ryegrass are the most competitive cover crops with 13.7 t/ac corn yields with alfalfa cover compared with 15.6 t/ac for the control and 15.6 t/ac corn yields with annual ryegrass compared to 18.3 t/ac for the control. Data is available upon request.

Annual ryegrass is more competitive than perennial ryegrass and should not be used alone, to increase percent cover a mix of Italian annual ryegrass and perennial ryegrass is preferred for a total of 8 lbs/ac. A study to look at other inexpensive grass species which may be less competitive will be conducted. The pre-emergence treatment of Pursuit and Python has been shown to cause corn injury when there are conditions that inhibits rapid corn emergence even with Clearfield corn hybrids resistant to Imidazolinone herbicides. Due to favorable conditions this was not seen in 1999 and 2000 but was experienced in 2001 and 2002. When you have this injury to the corn, the corn does not shade the cover crop quickly enough and competition is evident this treatment will be dropped or modified. The use of Python with Eradicane pre-plant incorporated did not show this injury and conventional corn hybrids can be used; this limits your cover crop choice to legumes. Much research has shown that post emergence herbicide timing is very important with recommendations for mid post applications when the weeds are 2 to 3 inches tall. This is even more important in this system, depending on the herbicide used, since the cover crops won’t be adequately suppressed if they get too mature.

In many small demonstration projects, the management of the small acreage by the farmer is sometimes delayed to get the majority of his field work done first; also, custom spray applicators may not get to the field when it is ready. This is especially true when spraying imidazolinone herbicides on Clearfield corn hybrids. Work is concentrating on herbicides like Accent, Calisto, Eradicane and Buctril which can be used with conventional corn hybrids. We are also continuing work with the Clearfield hybrid system using Lightening and the use of the combination of Accent and Pursuit at reduced rates to increase suppression on legumes.

Collaborators: