A Study to Look at Practices Aimed at Reducing Mechanical Cultivation in Organic Corn Production
A collaborative study was established to look at weed control in organic corn production. The impact of row spacing and cover crops was investigated to measure;
1. The thinning effect of each cultivation pass (flex tine harrowing and row crop cultivation) on corn plant population.
2. Whether narrow row corn would reduce the need for mechanical cultivation and if there was a spacing that provided better weed control from early canopying of the crop.
3. Whether inter-seeding a cover crop into organic corn at the timing of the final cultivation would provide enough ground cover and competition to reduce weed populations without reducing yield. A grass, 2 legumes and grass/legume cover crop, were compared.
There were several objectives of this study. One was to measure the effect of population thinning from tine weeding. The second was to assess the impact of narrow row spacing on weed control and the third to assess the weed suppression effects of several cover crops established at the time of the last cultivation. All of these treatment effects were compared by measuring yields.
This study had two field sites with two cooperating farmers. Twin Oaks will be referred to as site 1 and Bundy Creek Farm as site 2.There were two treatment effects. The main treatment of row spacing; either 30 inch or 15 inch and a subtreatment of cover crop. The 4 variations of cover crops were annual ryegrass, red clover (grazing type), kura clover (annual) and a mix of annual ryegrass with the red clover. All plots were tine weeded at least once. The 30” plots were also cultivated with a row crop cultivator. Population counts were taken twice at site one and once at site 2. A population count was also taken from the hand harvested area at site one. The weed growth was too intense to allow hand harvest of the plots at site 2. These plots were harvested mechanically and the loads were weighed. The data has been collected but not yet analyzed. The cultivated plots had much less weed pressure and the plants appeared more vigorous through the season and displayed less stress at the end of the season. The plants in the narrow row plots were shorter, more spindly and had smaller ears.
The two field sites had different soil types and different weed complexes. Early in the season site 1 had a fairly strong population of quackgrass. It seemed to fade later in the season and was replaced by ragweed as the dominant weed. Three tine weedings and two cultivations were done at this site. Cover crops were seeded about 1.5 weeks after the final cultivation, July 11-13. At that time the corn was chest high and the annual broadleaf weeds nearly as tall. The cover crops were able to establish in the cultivated plots but weed cover in the narrow rows prevented consistent germination. Where the cover crop seedlings were detectable in the field their growth remained insignificant. There were completely overwhelmed by the crop and weeds in the field.
Site two had even less success with cover crop establishment because the ground cover with weeds, mainly annual grasses and particularly crabgrass prevented the seeds from even making seed to soil contact. Cover crops were seeded July 14-15. The corn varied from knee to waist high. Rain and wet soil conditions prevented Site 2 from completion of a second row crop cultivation. The crabgrass had the chance to establish and the tine weeded could not adequately disturb the root systems. Although the weed competition was significant in the field and the corn looked stressed, the final yield seemed better than what was expected from observation. The yield analysis will provide interesting information.
The study was performed and data collected. I have yet to complete the statistical analysis of the data.
A field day was held Sept. 2 in Truxton, NY which is locatied in south central NY state. The field day was hosted by the Arnold family, one of the cooperating farms in this study. Bob LaFrancois, a student and mentor of mechanical weed control was a featured speaker. Bob explained the differences among makes and models of tine weeders, their best fit for crop and weed in the field and adjustments for best operation. His talk was enlightening, practical and very valuable. A display of pictures provided a history of the plots. We toured the SARE plot, the organically managed forage and grain fields of the Arnolds and a demonstration plot of grazing brassicas. There were 28 attendees. Many of the attendees travelled several hours to attend the field day. Kathie Arnold, gave her time to talk with attendees one on one after the tours were through. Judging from the discussions, questions and feedback from attendees it was a valuable day spent.
Impacts and Contributions/Outcomes
The outreach efforts associated with this study provided a valuable learning experience with very practical knowledge in mechanical weed control for organic row crop productions. It provided a forum that contributed to the organic community and a gathering for folks to share their experience and learn from each other.
The field study provided a season long connection to an organic corn production season for the regional extension educator. Although the study did not exhibit the results we had hoped for it was an invaluable learning experience for all involved. And what was learned will continue to be extended in future meetings and articles as well as personal interactions.
From my experience and observations this field season, cover crops would need to be established the season prior and winter killed or suppressed in some other way such as rolling at the time of flower to provide significant weed control. Their establishment in this trial can only be described as too little too late. The window where weed control needs to be done had passed.
Once the final summary of the data is completed more outcomes will be articulated.
Area Extension Field Crops Specialist
Cornell Cooperative Extension
60 Central Avenue
Cortland, NY 13045
Office Phone: 607-753-5215