Development of an organically managed baby greens production system: a multidisciplinary approach
The organic production of baby green vegetables in muck soil presents multiple challenges, especially the management of weeds and insect pests. This project evaluated various production systems to optimize yields while managing these problems.
- Quantify the impacts of cover crops and organic fertilizers on yields
- Determine the redheaded flea beetle trapping potential of various attractive plants and quantify the damages on spinach crop
- Establish relationships between meteorological data (air and soil temperatures, soil moisture) and weed emergence to develop emergence models and improve delayed seedingass, stale seedbed and seedbed preparation practices
- Assess the effectiveness of mechanical weed control equipment (cage weeder, bar arrow) and bioherbicides in delayed seeding and stale seedbed
- Determine optimal irrigation conditions to promote weed emergence before leafy greens are planted
- Assess the effectiveness of bioinsecticides used alone or in combination with natural predators on pest populations
- Assess the impact of production systems on the incidence of plant diseases and the effectiveness of the control strategies adopted
Two sites were established in 2018 and 2019 at IRDA's Organic Agriculture Innovation Platform in St-Bruno-de-Montarville, Quebec.
At site 1, consecutive cycles of green romaine lettuce and spinach were established. Nine treatments combining different cover crops and fertilization methods were repeated 3 times in the field for a total of 27 experimental plots. Four combinations of trap plants were also integrated in the design to evaluate their attractive potential on the redheaded flea beetle. Lettuce and spinach yields, as well as the number and biomass of weeds were determined at harvest for each plot.
At site 2, crops of red curled lettuce (2018), red romaine (2019) and arugula (2 years) were produced. The design included three types of cover crops in main plots repeated three times in the field. For each main plot in 2018, six treatments of mechanical weeding combined or not with bioherbicides were evaluated, for a total of 54 experimental plots with weed monitoring. The effectiveness of weeding practices was determined at each pass and at harvest, by counting weeds in each plot, and by measuring weed biomass and crop yields. Integrated into these plots, three treatments including bioinsecticides and natural predators as well as a control were repeated six times in the field, for a total of 18 plots with insect monitoring.
At the edges of Site 2, weed emergence modelling collected preliminary data on weed emergence dynamics based on the time of year soil preparation takes place.
Results and conclusions
At Site 1, combining the two-year trials, lettuce yields were significantly higher with fertilization including compost, while pelleted poultry manure increased spinach yield.
The irrigation trigger guideline determined with the "turning point" approach was established at values between -25 and -30 kPa for green romaine lettuce, under the conditions of the study (soil, biomass and weeds). Water losses due to evaporation and withdrawals from romaine lettuce and spinach crops mainly occurred in the first ten centimeters of the soil. The positioning of the tensiometer should therefore not exceed this depth for nearly 75% of the growth period for romaine lettuce, while it could be maintained at 10 cm for the entire season with spinach.
The cover crop had no effect on lettuce and spinach yields. The presence of cover crops or the fertilization method had very little impact on weed populations.
Finally, the trap crops incorporating several species were more attractive than the one including only amaranth. The presence of weeds and the lack of water had a significant negative effect on the germination of attractive plants. It is therefore important to apply good weed management and irrigation in order to use trap crops as a control method.
At Site 2, the results of the two seasons demonstrated the importance of adjusting mechanical weeding equipment, particularly the bar harrow. In 2019, the density of weeds in plots weeded with the bar harrow was approximatively 23% lower. Irrigation also played an important role in stimulating weed emergence during the period of stale seedbed. However, in this study, one irrigation was as beneficial as two irrigations. In addition, plots irrigated once or twice had a similar amount of weeds at crop harvest. Finally, the use of bioinsecticides or bioinsecticides combined with natural predators did not demonstrate statistically significant effects on harvest damage for red curled lettuce and arugula. The use of natural predators may be of interest in cases where there is no registered plant protection product.
More testing is required to consolidate the trends observed following the two years of the study, particularly with regard to the use of natural predators, the impact of irrigation on weeds during stale seedbed and to calculate crop coefficients (link between water withdrawal and evapotranspiration). More data is also required to refine weed emergence models.
|Name of Scientist or Technical Expert Team Member external to AAFC (carrying out research)
|Caroline Côté (Activity Leader)
|Hervé van der Heyden
|Daniel Malenfant and colleagues
Vegpro International inc. is the largest fresh vegetable producer in Canada. Vert Nature inc., its corporate farm, is dedicated to baby greens conventional production and produces approximately 2 400 ha of baby greens annually, including 1 400 ha in Québec and 1 000 ha in Florida. Vegpro International inc. distributes organic ready-to-eat baby greens blends grown in California, due to production constraints in the Québec and Florida areas, especially adverse climatic conditions and high pest pressure. To increase its competitiveness and reduce its reliance to production in California, Vert Nature inc. wants to develop a large-scale organic production of baby greens in Canada.
The general objective of the project is to develop an organically managed baby greens production system. The experiment will be conducted at the Organic Agriculture Innovation Platform of the Research and Development Institute for the Agri-Environment (IRDA) located in Saint-Bruno-de-Montarville (Quebec).
Two fields will be dedicated to the project, «Field 1» having been used for an Organic Science Cluster II project entitled «Impact of cover crops and organic fertilizers on organic carrot yields and safety in muck soil». Long-term experimental plots were established 3 years ago and carrots were grown in 2015 and 2016. The factors to be investigated include cover crops (oat, forage pea, and control) and organic fertilizers (chicken manure pellets, compost, and control). Cover crops are included for their ability to reduce muck soil degradation caused by wind erosion and carbon oxidation. They can also have other effects on many parameters like weeds and plant diseases. Baby greens (lettuce and spinach) will be produced from 2017 to 2020 on these plots to evaluate the impact of the treatments on crop yields and quality, and pests. Research activities realized in 2017 are financially supported by the Ministère de l’Agriculture, des Pêcheries et de l’Alimentation du Québec (MAPAQ). Treatments will be evaluated to reduce populations of flea beetles. These will include 3 trap crops, each one associated to a cover crop. Weed emergence will be monitored over several crop production cycles on cultivated and non-cultivated lands in order to establish relationship between meteorological data (air and soil temperature, and soil moisture) and seedling emergence. Meteorological data will also be used to develop sound irrigation strategies and will contribute to optimize false seedbed operations. Overall, this will contribute to 1) reduce costs linked to non-cultivated lands; 2) improve weed control and; 3) reduce muck soil degradation of uncovered soils.
The experiment in «Field 2» will look at cover crops of fall rye, buckwheat and oat mix, and control, and combinations of weeding operations: flex-tine harrow, rolling harrow with cage rolls, herbicide 1 and herbicide 2. Treatments evaluated for the control of thrips and flea beetles will include bioinsecticides and natural enemies. Two production cycles (baby lettuce and arugula) will be realized after weeding operations in 2018 and 2019. Evaluated treatments will include biopesticides applications and mechanical weeding operations, with the objective of reaching the best crop yields and quality while respecting environmental and public health issues.
Publications and Other Resources
Podcast: Organic Science Conversations- Young Shoots in a Flowery Garden at the IRDA
Organic Science Canada (Spring 2022)- https://organicfederation.ca/resource/organic-science-canada-spring-2022/snippets/
Last updated: January 2022
Tthe Organic Science Cluster program is led by the Organic Federation of Canada in collaboration with the Organic Agriculture Centre of Canada at Dalhousie University. Organic Science Cluster 3 is supported by funding from the AgriScience Program under Agriculture and Agri-Food Canada’s Canadian Agricultural Partnership (an investment by federal, provincial, and territorial governments) and over 70 partners from the agricultural community. More information about the Organic Science Cluster Program can be found at, www.dal.ca/oacc/OSC.