b"Diversity Not Key When ItComes to Cover CropsDespite former claims, cover crop diversity may not be thebest for weed control in your fields. BY: ASHLEY ROBINSONWHEN IT COMES to cover crops, the claims of what they can do for your fields are wide and varied. However, those claims dont all live up to the test including ones about the benefits of crop diversity.At the International Potato Technology Expo in Charlottetown, P.E.I. on March 31, Aaron Mills, research scientist with Agriculture and Agri-Food Canada (AAFC), spoke about crop rotations and cover crops. He mentioned a study done by AAFCs Andrew McKenzie-Gopsill who showed the effect of diversity on weed control in cover crops. I get the sense that cover crops are becoming more and more popular. And I also get the sense that a lot of people are planting them without really knowing why they're planting them, Mills says.There has been a lot said about cover crops over the years, and through numerous studies some of those so-called benefits have been debunked while others have lived up to the hype.We tend to think that more diversity is better. But from a weed control standpoint, if that's what you're going for with your cover crops, it was hard to tease out the effects of these diverse mixtures versus really strong cover crops in the monoculture, Mills explains speaking about McKenzie-Gopsills study findings. The crop rotation trial plots at the AAFC Harrington Research Farm in For example, buckwheat and sorghum sudangrass were usedP.E.I. in 2021. PHOTO: AARON MILLSfor a cover crop mixture, and while the two are highly effective for weed control they dominated the mixtures. Mills adds if you wantbeing used as cover crop rotations. There were a few phases of weed control, through crop, it's better to focus on specific cropscrop rotation studies completed before the switch to potatoes that are members of the mixture than to mix them all together. as the main crop took place, with the initial years finding the One thing to keep in mind when planning crop rotations withhighest yields were recorded from rotations with one cash crop cover crops is, longer is better. When you have a tighter rotationeach in them.then you run into problems, Mills says. Mills five-year study compared three different potato rotations and three different levels of diversity with cover crop mixtures. Crop Rotation Study The crop rotations including potato were barley and ryegrass, In a five-year crop rotation study led by Mills, he took over studybuckwheat and brown mustard, field pea and ryegrass, sorghum fields which had previously been started with carrots as theirsudangrass and pearl millet, a commercial mix of a proprietary main crop in 2005. In 2018 the fields were switched to havingblend including grasses, legumes and oilseeds, and the Barrett potatoes as the main crop, leading to support and collaborationmix of buckwheat, sorghum sudangrass, peal millet, fava bean with the Prince Edward Island Potato Board. Mills study lookedand brown mustard. at the effects of cover crop diversity on potato yield and quality. The study found a higher diversity of cover crops in a mixture In Mills study, the trial fields were located at the AAFCdoesnt mean there will be a higher potato yield. It was also Harrington Research Farm in P.E.I. The initial crop rotationsdiscovered its possible to make just as much money in a rotation used carrots as the main crop, with barley and pearl millet,with only has potatoes as a cash crop compared to rotations barley under seeded with timothy and timothy, and barley underincluding potatoes and a secondary cash crop such as barley or seeded with timothy and timothy under seeded with pearl millet,peas. SPUDSMART.COM Summer 202233"