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Acid Rain in Hydroponics: What Growers Must Know · Hydroponics Daily

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  Hello there, welcome back to Hydroponics Daily, your go-to podcast for everything
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  soil-less cultivation.
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  I'm your host, Dr. Russell Sharp, and today we're going on a trip back to the
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  1980s because we're talking about acid rain and its effects on plant health.
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  So it hit the headlines in the 1980s, acid rain, but it still matters today.
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  We'll look at what it is, why it forms, and how it affects plants,
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  where and when it has occurred and finally why you need to be keenly aware of
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  the issues with acid rain even if you're growing indoors especially if you're
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  using foliar sprays so we'll talk about that.
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  Acid rain is not just rain but it can be snow or even fog that has been acidified by air pollution.
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  Normally rainwater is slightly acidic anyway and
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  it can be up to around pH 5.6 because carbon
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  dioxide in the air dissolves to form a weak acid called carbonic
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  acid but when sulfur dioxide and nitrogen
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  oxides from burning coal oil and gas whether
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  that's in a factory a home or traffic mix
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  with the water in the atmosphere they form much stronger acids
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  sulfuric acid and nitric acid if you've
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  ever used nitric acid in a lab you'll know it is effing
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  in certain expletive here horrible wicked evil
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  it's one of the just really horrible acids so
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  you really want to avoid sulfuric acid is not particularly nice either but nitric
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  acid is really bad and those two combined pull the rainfall ph down below four
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  and in some case cases that makes it 10 to 100 times more acidic than normal
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  rainwater because pH is a logarithmic scale.
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  So what does rainwater that is 100 times more acidic,
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  actually do to your plants well direct injury so
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  acid droplets on the leaves can leach away the protective waxy
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  cuticle and cause browns patches or
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  necrosis so normally leaves are covered certainly
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  the upper surface is covered with a waxy cuticle even
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  if you don't think of it as being a waxy leaf like a fig leaf
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  or something like that or an ivy leaf they still will
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  have wax normally on the cuticle to prevent excessive
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  excessive evaporation and to
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  prevent damage and acids will
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  dissolve this it'll also disrupt nutrients so acidic water washes calcium particularly
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  but also magnesium potassium out of the leaves and soils those those are essential
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  nutrients for growth so plants become weaker and then soil chemistry in soil-based systems acid rain,
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  mobilises toxic elements like aluminium, which can damage roots and block nutrient uptake.
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  And then there's the indirect stress. Plants under nutrient stress are more
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  vulnerable to disease, pests and drought.
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  The mycorrhizae won't like it either, so that's also something to consider.
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  So it's rarely just burning the
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  leaf. It's more about long-term nutrient imbalances, particularly calcium.
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  So where has it occurred? Acid rain
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  was most notorious in the 70s and 80s in europe and
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  north america especially downwind of coal
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  burning power plants forests in germany's black forests lakes in scandinavia
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  ecosystems in the north eastern united states were badly affected i think around
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  los angeles particularly international agreements like the clean air act amendments
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  in the u.s and similar policies in europe reduced sulfur dioxide.
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  That, my friends, is a government alert on my phone. Well, thankfully that was just a test, and...
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  There are no nuclear bombs or power plants exploding anywhere near me.
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  So yeah, thanks for that, UK government. You've just ruined my podcast.
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  So where was I? I was in the northeastern United States. I know I'm badly affected,
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  but clean air laws have been passed.
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  So acid rain has declined since the 1990s, just like the ozone hole is repairing
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  itself thanks to the Montreal Protocol, the effects that were brought in there.
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  That said, it's still an issue in parts of China and india so those hydroponic
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  farms we talked about all those farms we talked about yesterday could be still
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  suffering from acid rain especially where coal is a major source.
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  So now what's this got to do with hydroponics well
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  you might get some acid fog coming in through
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  your inlet filter but the main one is telling you
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  to avoid acidic foliar sprays there are
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  a lot of products on the market there that say can also be applied as a
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  foliar spray if diluted and these products have
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  got phs of one or two things like
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  this really acidic products a lot of them are like propagation starting
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  fertilizers that you think would be really gentle
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  and good for your plants a lot
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  of one part fertilizers obviously not liquid gold
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  or as it's called in the us gold leaf our
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  product that's a one part fertilizer that's always at
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  the sweet spot for ph so can be used as a
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  folia with no issues but if you've got any product
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  that is really acidic do not put it
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  on your leaves because it will strip the calcium off
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  them and you'll get all sorts of issues resulting from that really weak horrible
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  growth that is highly susceptible to attack by pests and diseases not least
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  and will die at the first environmental stress that they're given if in doubt
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  just do a quick ph test on any foliar spray you're about to put on your plants.
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  Most people only put foliar sprays on in vegetative phase
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  anyway so to sum up acid rain is
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  a product of industrial pollution in and the
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  formation of nitric and sulfuric acid but it can also be
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  mimicked accidentally by the application of acidic foliar sprays so be careful
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  out there don't be putting any foliar sprays on there too acidic as always my
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  final request is that if you found any value in today's episode please please
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  please i'm begging you go and do an apple podcast review because it shoots us
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  up the charts and i want to get as high as possible because i want
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  hydroponics to be in the top 10 of gardening and
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  science podcasts in the uk us and elsewhere
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  because then it'll just snowball from there and people
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  will share it and find it much more easily
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  so thank you very much for listening i'm off to exhibit a trade show for lawn
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  care which will be fun that will be 5 000 middle-aged white men most of them
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  bald standing around talking about grass fan dabby dozy see you tomorrow goodbye.