Field Day Recap
Field vegetable growers in the Lower Mainland implement cover cropping as a practice to supportsoil and nutrient management objectives, but have outstanding questions about the performance ofspecific varieties against their goals. As supportive research for the BC Living Lab, Delta Farmlandand Wildlife Trust conducted a fall variety trial to assess the characteristics of 20 cover species inLower Mainland growing conditions. At the trial site in Ladner, growers compared varieties thathad been monitored for height, plant cover, and weediness as candidates for winter cover cropping.
Finding the Right Fit
Cover crops in annual vegetable cropping systems are generally managed to be present in abundance overwinter and to be reduced or absent by the time crop seeding begins in the spring. Beyond these basics, growers discussed the characteristics they select for that can address farm conditions – in the Lower Mainland, weed suppression, nitrate retention, reducing erosion, and building organic matter were commonly cited priorities. In this trial, researchers were also considering:
- Plant height. In this trial, grains like oats,barley, and triticale were tallest, brassicas liketurnip, tillage radish, and legumes like fababeans were mid-height, while peas and cloverswere shortest.
- Susceptibility to winterkill: Cover crops thatdie back overwinter can be preferential as theyrequire less cultivation to make for springseeding.
- Risks of pests and diseases: Brassicavarieties are biofumigants that can repel someinsect pests, but can also host challengingpathogens like clubroot.
In-Field Insights
Most growers noted that they use barley as their primary winter cover crop, and some discussed howits affordability had made them less likely to consider other varieties. Seeing 20 varieties side-by-sidecreated a lot of interest and excitement in alternatives to barley – most growers left with a handful ofvarieties they were interested in trialing on their farm. The cover crops were lush and vigorous in lateOctober, but researchers are interested to see how comparisons of characteristics may change overthe winter. For the BC Living Lab, these observations also look at how they’re supporting climategoals, by storing soil organic matter and holding nitrate overwinter.
What’s Up Next?
The BC Living Lab’s collaborative approach emphasizes the value of trialing, observing, and adaptingpractices to fit each farm’s goals and conditions. While working with growers to trial feasibility onactive farms, researchers are continuing to assess how a winter cover crop mix performs in potatoesfor weed suppression, plant coverage and nutrient management, and will adjust varieties as needed.Compost application and split nitrogen application in potatoes are also being trialed to see how theymeasure up for climate, productivity, and economic goals.