Mulch enhances edamame survival and yield
Sustainable Agriculture Student Research Project
Trialing Edamame Varieties and Mulch in Richmond, B.C.Naomi Waite, Department of Sustainable Agriculture, 2024 |
Introduction
Edamame, also referred to as vegetable soybeans, are soybeans (Glycine max) harvested before full maturity. Its reputation as a health food has expanded its market beyond its Asian origins. This may be a market niche that growers, especially those in mixed vegetable production, could potentially capitalize on in the Lower Mainland.
The purpose of this study is to make recommendations for local growers on suitability of different accessible varieties of edamame, as well as their consumer appeal. This study also investigates using compost mulch to decrease weed pressure and improve plant performance.
Research Questions
- What varieties of edamame are best suited for growing in the lower mainland?
- Will mulching with compost reduce weed pressure or otherwise improve plant performance?
- Which variety is the most palatable to consumers?
Methods
Location: KPU Farm, Garden City Lands, Richmond, B.C.
Design: Randomized complete block split-plot factorial design (Figure 1)
Four varieties were selected for this study based on performance in other studies as well as availability: Envy (E), Midori Giant (M), Tohya (T), and Chiba Green (C). Plots were split into mulched and unmulched, with four subplots that contained each variety in random order. The total study area was 31.2 meters by 1.5 meters (46.8 m2) (Figure 2).
Edamame was direct seeded, 16 seeds/plot. Irrigated with drip tape in early stage of experiment, left unirrigated once plants had established. Mulch was spread approximately 1.5 cm deep in respective plots.
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Unfortunately, wet weather combined with irrigation issues and bad drainage led to water ponding twice on a portion of the research and required a late reseeding in the affected plots (Figures 3 & 4).
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Data Collection
- Plant performance
- Germination/survivorship (counted at harvest)
- Yield, in grams per sq. m.
- Weed management difficulty in time spent weeding
- Taste testing
- Preparation: 100 grams of edamame pods with ends removed were cooked in boiling water for 4 minutes. After cooking, they were cooled at room temperature before stored overnight at 4℃. Tasting occurred the following day.
- Each variety was scored for three characteristics: taste, texture, and pod feel
- Scored on a 1-5 Likert scale from unpleasant to very pleasant
- Seven participants
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Statistical Analysis
All analyses were conducted using jamovi interface for R.
- Yield data and germination data evaluated using mixed-model analysis as well as an ANOVA
- Dependent Variable: yield/m2 OR germination
- Fixed Factors: variety and mulch status
- Cluster Variable: block (mixed model only)
- Tasting scores analysed using ANOVA
- Dependent Variable: taste, texture, and pod feel (analyzed separately)
- Fixed Factors: scorer, variety
- Weed management
- Analysed using paired samples t-test
Results
Plots with mulch had significantly improved yield and survivorship (p<0.001), whereas variety had no significance effects (Figures 6 & 7). There were also no significant interaction effects. Weeding time was not statistically different between blocks (Figure 8). There were no statistically significant differences in taste-testing scores between varieties (Figure 9). There was a significant block effect on germination and yield (p<0.05).
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Discussion
- Mulch promoted edamame survival and yield.
- Weeding time was only recorded four times over the season and did not differ between treatments. The study would have benefitted from more measurements.
- While not measured in any quantitative way, weeding by hand was much easier in the loose mulch as compared to the heavy clay soil.
- As yield depends on germination, plots with good germination naturally had more harvestable pods.
- The significant block effect is likely due in part to the greatly reduced yields in the replanted plots (unmulched block 2), as they did not get the same heat units earlier in the summer like the other edamame seedlings.
- The “Envy” variety had the most mixed reviews during the taste test, a few comments suggested that the dark hairs on the pods were unappealing.
Conclusions
- Compost mulch improves germination and yield of edamame.
- Time spent hand weeding was not statistically different between treatments but was easier in the mulched plots.
- Differences in yield between varieties is inconsequential.
- Variety palatability depends on personal preferences.
Acknowledgements
Thank you to Mike Bomford, Ben Alles, Alex Lyon, and Sahar Zandieh for their assistance and guidance of this study, and the 2024 agroecosystem management class for taste testing the samples.
Citations
Carneiro, R. C. V., S. E. Duncan, S. F. O’Keefe, Y. Yin, C. L. Neill, and B. Zhang. 2020. Sensory and Consumer Studies in Plant Breeding: A Guidance for Edamame Development in the U.S. Frontiers in Sustainable Food Systems 4.