Hi,
What this suggests to me is that we need some basic science on the
contaminants in various types of wood ash.
I too have an allotment and
quite a few of books on vegetable growing suggest wood ash as a source
of potash for certain plants.
What does astound (but no longer
surprises) me is that 40 years after the rude awakening of Love Canal a
lot of the basic science around both commonly used chemicals and
contaminating human activity, remains sparse.
Presumably at some point
we will be guiding all of our activates on this planet with a robust
scientific approach and not trusting to either out-dated approaches or
unnecessarily precautionary restrictions.
Apologies for the rant
Nick Merriman MSc MRICS MIQ Mineral Valuer, Valuation Office Agency, 2
Broadway, Birmingham, B15 1BG 03000 503 078 Tel 0771 347 0580 Mob
nick.
[log in to unmask]
From: Taylor, Christopher
Sent: Wednesday,
April 22, 2015 11:12 AM
To: [log in to unmask]
UK
Subject: Re: Wood ash vs coal ash and IBA/FBA and all that
Hi Neil
Thanks for your email, you raise some interesting points.
I have
tested 9 allotments in my borough. All were previously fields, then
allotments, so no industrial use. Benzo(a)pyrene ranged from 0.1 - 26.3
mg/kg, and we did not sample from any "burning hotspots".
If only
allotment holders just burned the previous year's plant growth!
Anything from old compost bags, treated wood, plant pots, polystyrene
trays goes onto the bonfire.
Also, not everyone burns and uses ash.
Those who do, do so out of habit and have done so for years, so the PAH
levels vary considerably from plot to plot.
My thinking is, why would
you want to spread sooty potentially carcinogenic waste on the soil you
choose to use to dig in and grow something you eat? Spreading it in a
Swedish forest in one thing, but having the soot in contact with your
veg, and the dust in your lungs and on your skin?
- if it's for the P,
K, N use fertilizer, compost, manure or commercial potash from marine
deposits, as the quantities of these in your ash will be minimal
- if
it's to dispose of waste, compost or mulch instead
- if it's to adjust
the pH, use lime or ericaceous compost
- if it's to deter slugs, use
hair, crushed egg-shells etc
And what is the impact of ash on soil
organisms? I imagine a soil that has compost instead of ash to be
healthier.
I suppose this practice is similar to views on smoking.
The "My granddad smoked for 70 years, and it didn't do him any harm"
mentality. But most people have an allotment for a healthier lifestyle
choice, and spreading ash just seems contradictory to this.
And one
final thought... if I find BaP at 20mg/kg in your allotment plot where
you have been spreading ash for years, would you be the Class A person
under Part 2A? Hmmm...
Regards
Christopher Taylor
Enforcement
Officer
Regulatory Services
Brent Council
Tel: 020 8937 5159
www.brent.gov.uk
-----Original Message-----
From: Contaminated
Land Management Discussion List [mailto:CONTAMINATED-LAND-
[log in to unmask]] On Behalf Of Neil Scott
Sent: 22 April 2015
08:57
To: [log in to unmask]
Subject: Re: Wood
ash vs coal ash and IBA/FBA and all that
A couple of thoughts:
Plant
matter gets burned on allotments to get rid of diseased material and to
kill pests which would survive composting.
The discussion has
considered burning of wood and the likelihood of accumulation of pah,
however most of the material being burned will be last years growth
which is at most a year old. I'd have thought that this was different
to bringing wood on to site to burn.
As the volume of ash will be
small, if its well spread any contaminants will be dispersed - unless
there is a regular spot used for fires which would then be a hot spot.
Brassicas (cabbage family) have been touted as useful as bioacumulators
of metal in soil - they also have woody stems and are likely to be
burned. Is this a mechanism for building up metals in the soil if
repeated over many cycles?
Chimney soot is also used as a soil
improver and to help the soil warm up in the spring, as surface cover,
this practice would have significantly raised levels of contaminants
I'm sure.
Testing we've done on allotments has only shown elevated
levels on areas repeatedly used for fires.
Anyway I'd better go to my
allotment I've a box of matches in my pocket and heap of stuff drying
out nicely with all this sun...
Neil Scott
Senior Scientific Officer
Eastleigh Borough Council
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