This year we carried out demonstrations on 3 biodegradable mulches and 3 non-biodegradable mulches to see how they compare in a sweet potato production system here in Nova Scotia.
As horrible as this year turned out to be, it was the
perfect year to trial plastic mulches as for many they made the difference
between growing a marketable crop.. or not. Sweet potatoes are a challenging
crop to grow in N.S, they need a long season with warm soils to produce tubers
that make grade.
We demonstrated six different mulches, 3 biodegradable, and
3 nondegradable to test a variety of colours and thicknesses/material. There was a
30% difference in yields between the highest and lowest performers as well as differences in tuber grades (sizing) for each mulch. Before I talk
about the treatments, it’s important to remember that this is not a replicated
trial; the results highlight striking differences between mulches, but this is
by no means conclusive.
Treatments:
-
Dubois, black, 1 mil embossed plastic (non-degradable)
- Heartnut Grove, green, 1 mil (non-degradable)
- Solar Shrink, black, 0.5 mil (non-degradable)
- Film Organic “88”, black, 0.8 mil
(biodegradable)
- Dubois Bio360, black, 0.5 mil (biodegradable)
- Dubois Bio360, clear, 0.5 mil (biodegradable)
Method:
- 3 rows, 400ft long, of each of each mulch was
laid on June 13, 2023. Raised beds were 10" high, 28" wide.
- Slips planted in late June. Management practices
identical to rest of field (fertility, pesticides, etc)
- 12ft sections from each row were harvested Sept
19. Weighed for above and below ground biomass; tubers graded with a standard
sizing board (<1.5”; 1.5” – 2.0”; 2.0” – 3.5”; >3.5”).
Results:
The table 1 below details specific results, with green
highlighting showing the best performer in each category/column. Here are some
brief takeaways:
- The three non-degradable mulches produced the
highest grade A (2” – 3.5”) tubers.
- The green mulch produced the highest average
weight per tuber (160 g) and stimulated root growth over shoot growth (root to
shoot ratio).
- The two Dubois biodegradable mulches were
slightly too thin. The black 0.5 mil adequately controlled weeds but was
severely degraded by September. The clear 0.5 mil had ruptured by July 20th
and was overrun by weeds.
- From these results I would recommend choosing a
black biodegradable mulch no thinner than 0.6 mil and a clear biodegradable
mulch no thinner than 0.8 mil.
- We did not assess the cost difference between
each mulch or consider the added cost of removing nondegradable mulches at the
end of the season. These costs needed to be factored in to determine the profitability
of using each mulch.
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| Table 1. results of mulch demonstration |
Please reach out to me at tmorcom@perennia.ca to discuss mulches, our results, or your plans for next year.
Tim
