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Nitrogen choice: The Key to Hydroponic Success · Hydroponics Daily

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  Hello and welcome back to Hydroponics Daily. I'm your host Dr.
• 0:03
  Russell Sharp and this is the podcast for all your soilless cultivation.
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  Today is the long-anticipated episode on nitrogen in all its forms and we're
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  going to do a deep dive into the forms of nitrogen.
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  So not what are the symptoms of nitrogen deficiency and things like this.
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  Why plants need nitrogen.
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  We've discussed that on a previous episode really early on in probably January or February.
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  So it's the most demanded nutrients plants
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  need the most of any nutrient so we'll talk about
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  that it's key it's the one nutrient that's really going to stop growth some
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  some farmers broad acre farmers
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  growing crops they arable crops
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  they just add nitrogen and no other fertilizers because
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  they just rely on the soil for everything else and they get the most bang
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  for buck from adding nitrogen however there's a new fertilizer
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  tax in the uk and so the the
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  choice of nitrogen may change so we've said
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  previously that nitrogen is needed for chlorophyll production proteins
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  amino acid synthesis dna synthesis but in
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  hydroponics you've got to choose the right form because it's crucial because
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  it will affect ph root zone biology crop quality
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  and even pests susceptibility so the
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  most commonly used form of nitrogen in hydroponics is
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  nitrates that's a nitrogen atom connected
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  to three oxygen atoms and if you know your chemistry you'll
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  know that that involves it having a negative charge and
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  so it is an anion get
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  me so it's nitrates is most commonly used it's easily immediately available
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  to plants it diffuses really quickly through the plant it doesn't it's not volatile
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  so it doesn't gas off or convert rapidly it helps maintain a stable ph slightly alkalining effect.
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  And it's easy to control in recirculatory systems.
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  The disadvantages are that overuse can promote watery stretched vegetative growth,
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  and it may accumulate in leafy greens if applied in excess, so when we talk about,
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  blue baby syndrome and nitrate levels in crops but you need to be careful of
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  that and if it's allowed to run off so if you run to waste and it's got a big
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  environmental footprint and the environment agency in your country will come
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  after you if you are releasing lots of nitrates.
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  Interestingly in holland they caught people releasing
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  fertigation from a hydroponic greenhouse
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  large hydroponic greenhouse because they were doing it in winter and
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  the snow was melting around the pipe where they were doing it absolute idiots
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  but as i say normally nitrates
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  are balanced with some ammonium and that
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  is one nitrogen atom connected to four hydrogen
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  atoms and if you know your chemistry you'll know that that is a
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  cation it's got a positive charge so and it'll have
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  a slightly acidic effect and it
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  will balance that sort of leggy growth that you get so
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  in gold leaf or as it's called in the UK liquid gold we have
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  a nice balance between ammonia and nitrates whereas
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  a lot of A and B fertilizers they just go
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  for the nitrates and instead of ammonium they add a lot of potassium
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  and that comes with other disadvantages we like to have a nice balance of ammonia
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  and nitrates and a good amount of potassium but not too much it requires less
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  energy for uptake in the plants plants can absorb it quickly ammonium and it
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  stimulates early growth and root formation to balance in that vegetative growth.
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  So it works synergistically and blends with nitrate. Disadvantages can lower
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  the pH, can lead to root zone acidification.
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  Plants will pump out a hydrogen atom for every ammonium they get out.
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  And as you pump out hydrogen atoms and you get an accumulation of hydrogen atoms,
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  that's what acidity is. So that's where you get acidity.
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  Higher doses can be toxic in closed loop systems. You
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  can get ammonium toxicity and it can interfere with calcium uptake
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  and lead to tit burn if you're not careful so just
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  make sure you use a properly formulated source of
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  ammonium then there's urea which is
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  as well as nitrogen atoms and hydrogen
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  atoms you get a mixer you get a carbon atom and
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  an oxygen atom in there and this is often found in cheaper fertilizers
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  so urea is a nitrogen source that needs microbial conversion
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  or the plant to use urea's enzymes
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  which happens slowly so the advantages
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  of urea is it's high nitrogen content by weight it's non-corrosive
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  and easy transport but sometimes using
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  foliar feeds especially popular in regenerative agriculture sort of melting
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  urea and put it on as a foliar i'm not a big fan and also it also leads to people
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  you put on a cobalt and nickel which i'm not a big fan of you know me on social
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  media you know that i say that people who use those fertilisers shouldn't be
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  able to sleep at night because they're carcinogenic.
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  Anyway, urea, it's not used massively in hydroponics because the disadvantages
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  are it requires that urease enzyme, which are thought to be predominant in microbes,
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  but I think plants can also have it, to convert ammonium to nitrate.
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  It's ineffective in sterile and soilless environments because of that need for the bacteria.
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  It can cause ammonia toxicity if it's broken down too fast, and it can raise
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  the electrical conductivity.
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  But it is cheap as chips, so that's why it's used.
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  But like the chlorides in kelmags, they're cheap as chips.
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  Or the kelmags in fostrogen, they're really cheap. Or in Miracle-Gro, they're really cheap.
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  So urea is a cheap fertilizer, and you'll find
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  it in cheap other sources we
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  talked about nitrogen pollution in the air and how certain plants
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  can absorb a lot of their nitrogen needs from
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  the air and that's a
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  good source if you've got the right plants like the magnolia and
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  cobras and eucalyptus phimilus talked about in the previous podcast
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  so pollution is a source of nutrition go
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  back to that episode and listen to that just received a phone
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  call there from my seaweed supplier so hopefully
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  we'll get some more seaweed down soon anyway back to nitrogens
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  it's obviously it's not a reliable controllable source
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  of nitrogen so don't rely on pollution and its uptake
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  is variable and species dependent you will find
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  that plants can absorb nitrogen from lightning
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  strikes and lightning strikes you would
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  not believe it but they well you might believe it they that
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  contributes a lot of nitrogen to the nitrogen cycle like
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  something like one percent something like that might even be higher let's
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  check here it is higher five to eight percent of.
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  The natural nitrogen cycling is contributed by
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  lightning crazy that isn't it so i think about that
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  and then obviously there is if you're growing legumes or alders
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  certain plant species that have bacteria in their root system the nitrogen can
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  be fixed in by symbiotic microbes from n2 nitrogen gas that's in the air around
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  the plants in the soil or the ground media however it requires host specific
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  microbe interactions and it won't happen in things like.
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  Hemp or hops or tomatoes
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  cucumbers these sort of hydroponic crops
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  they will not have any nitrogen fixation there will be free living
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  sort of like hippie nitrogen fixes in
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  the grow media but they contribute a tiny amount and
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  you'll see people selling microbial products that say
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  contains nitrogen fixing bacteria and yes maybe
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  they do but the amount of nitrogen that
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  they will fix is tiny tiny compared to the
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  amount you get from a fertilizer and also the first thing
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  a nitrogen fixing bacteria wants to do as soon as you put it in a product and
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  stick it on a shop shelf is die it's
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  not like a bacillus species they are very very intolerant
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  of storage conditions and so their shelf life is really small
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  it's one of the reasons i don't sell microbial products it's because they're
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  dying on your shelf whereas other products they
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  have a much longer shelf life one product one natural source
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  of nitrogen that i do stand behind and that's amino acids
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  and protein hydrolysates that just means proteins that
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  have been broken down by chemical and enzyme action some
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  fertilizer products contain amino acids or protein hydrolysates essentially
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  pre-digested proteins they're rapidly absorbed by
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  plants they can stimulate enzyme production and resilience enhance
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  flavor and aroma in fruits and herbs and may even
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  act as a mild biostimulants they sort of short circuit
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  the requirement to make amino acids it's a very intensive metabolic process
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  is making amino acids and by providing amino acids to the plants directly they.
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  Can absorb them and use them directly the disadvantages are that they're expensive
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  compared to things like ammonium nitrate they can cause biofilm or microbial
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  growth in reservoirs if you don't use them correctly,
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  So they're often used as a supplement, not a primary source of nitrogen.
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  You would add them on top of and you wouldn't rely on them as a source of nitrogen.
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  And the effects are much more than just their nitrogen content.
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  So we've got a hop grower who uses them during establishments and has seen great
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  effects. And it's not just due to the nitrogen because the amount that he's
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  adding is tiny, like 150 grams per hectare is a tiny amount.
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  So they're great for stress recovery, flavor enhancement, establishment
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  during cold temperatures is where i recommend them
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  so like early spring in the uk where the light levels are
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  high comparatively but the temperatures are
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  low so if you're in hydroponics you want a good balance between
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  nitrates and ammonia avoid urea based products use amino
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  acids as a biostimulant rather than nitrogen source to supplement
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  your grow and monitor your ph and ec because your plants
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  may be absorbing one form of nitrogen in as
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  opposed to the other dominantly and that will shift your
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  ph say they're absorbing ammonia they'll be pumping out
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  hydrogen ions and that will reduce your
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  fertigation solution ph so hopefully
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  that's give you a bit of information about nitrogen if you want me to clarify anything
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  then let me know send me a message you think i've missed anything or
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  made a boo-boo then let me know i'm more than happy to clarify i'll
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  probably record another episode now on cal mags because
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  i said i was going to do that i've gotten a few at once because the
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  diggers outside the office have stopped working for the afternoon
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  they must be on strike so i can get a lot going because i'm
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  going camping this weekend and i don't want to be recording podcasts in
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  a tent it will sound terrible so hopefully this sounds a lot better than it
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  would in a tent next to the beach down on the south coast of england on the
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  english riviera it's been baking hot for three months now in the uk so you can
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  guarantee the weather forecast is rain this weekend because i am going camping
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  fantastic See you tomorrow. Goodbye.