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9 Key Facts Urban Farmers Must Know About Nutrients

What do beginning urban farmers (or even experts) need to know about fertilizer? We discuss this topic and much more in an exclusive interview with Nutri-tech solutions founder and plant nutrition expert Graeme Sait.

This is quite a long post (Over 5,000 words)! Skip to a specific section below if you want or download PDF:

Nutri-tech solutions background
1. Soil and growing medium and the link to the environment
2.The importance of fertilizer in growing
3. How urban farmers can easily manage plant nutrition
4.The "process" of setting up your first basic urban farm or garden
5. The biggest misconception urban farmers have about fertilizer
6.Increasing crop yield, preventing insects, measuring brix levels, profitable urban farming
7.The best tools for beginner urban farmers
8. Hydroponic and soil-less growing mediums + common mistakes
9. Additional book recommendations for urban farming beginners
More on Nutri-tech solutions


I guess if you just wanted to start off with sharing a little about Nutri-Tech Solutions and kind of what you guys do, your story and what your role is and we can start there?


G: Sure, I'm the founder of this company, called Nutri-tech solutions, in Australia, we started (the company) 23 years ago, it was a kind of a life changing thing, I had a daughter who was hit by a car outside of her school, and in a coma for 3 months, and she got worse and worse, had massive brain injuries, then one day, everything went haywire and all the machines were all beeping, and they said she was going to die within hours, and I kind of made this deal that if she survived, I would do something (to change the world) and not look back,  and shortly after making this deal she came out of a coma, and that was my life changing moment. I had a sleepless night and came up with the whole concept...I decided to become an expert in nutrition - human, animal, and of course soil nutrition and plant nutrition. 

And so I began that journey 23 years ago. We formed the company the day after that happened, we’re now in 55 countries, I was in 33 countries last year so a tremendous amount of travel, I've consulted with government, met with ministers and prime ministers and so forth, the main story has been driving home the links between the soil and climate change. That's what’s driving me at the moment.

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1. How are urban farmers and the growing mediums used by urban farmers linked to climate change?

G: A great deal, in fact, the lion’s share of the greenhouse gases in the climate, have directly come from the soil, we have lost 2/3 of our humus, (also known as) our organic matter, its called humus, and that humus is now part of the carbon cycle and is part of the atmosphere, and the answer is to put it back. When you build the humus, when you do the right things in the soil to build rather than lose humus, then, that is a bigger contribution (than) putting up solar panels, however the biggest contribution people doing urban agriculture can make is to build - start building the humus because that is literally sequestering carbon that would otherwise return into the atmosphere in the carbon cycle. So the building of humus (by simply practicing urban farming in the soil) is the solution.

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2. So, for somebody who’s just getting into urban farming, what do you think and how would you describe the importance of fertilizer as part of the whole system of

growing? 

G: Well, the starting point is to explain the importance of minerals in a home garden or in an urban farm full stop and understanding the very simple question and concept that we are what we eat and what we eat comes from the soil and soils are a shadow of what they used to be.

We have had decades of soil extraction - that's what food production has been, every time you take something from a field, you remove a little bit of all 74 essential minerals, the first soil from the Precambrian (era) had 74 minerals, and for many years, as we take food from the field, we take a little bit of everything, and we didn’t put much back. For a lot of years we just used N, P, and K, which is Nitrogen, Phosphorous, and Potassium, it was all that went back.

So you take out 74 and you put back 3, and that’s called mining the soil, and so  that has led to demineralization, it’s a led to impacting our health, and so our first goal is to replenish the soil when doing urban farming in this case, or home gardens, and producing output. 

As for the fertilizer, people think of fertilizer and they think “oh, were going to throw on a bit of NPK”, but were not talking about something as basic as that, were talking about the concept of whether a plant is healthy and resilient, whether it  is going to be fun urban farming – it’s all about the health of the plant, because the plant has an immune system that is fueled by all those minerals and the better you can do your nutrition (the better  the plant) - that is why we call it nutrition farming.

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3. How can urban farmers easily manage their plant nutrition?

You can take care of the nutrition and understand the spectrum of minerals easily: the very best thing for people to do is a comprehensive soil test, always,  it’s a very simple thing to do a soil test and then you find out,  and say well “that’s what (minerals) I need”, and once you correct those things (lacking minerals), that makes everything so much  more fun.

A lot of people who haven’t done this (soil test) before, get these spindly plants, covered in disease, covered in insects, and they say, “oh this is too hard”, but there is no accidents when that happens, everything comes back to nutrition. 

What's the easiest way to "break down" plant nutrition?

Nutrition is about: minerals, and micro-organisms, and humus, three things - that’s what nutrition farming is about. (1)minerals, (2)microbes, and (3) humus – there’s an interrelationship between those 3 things.

You can help your microbes with things like compost, and that is the role of compost, and that takes care of one part of the equation, but (next) you need to do a soil test, (so you can find out) exactly what you need to do with the minerals.

Note from Urban Vine: Step (3) humus, is best viewed as the result of properly doing steps (1) and (2), it is more of a by-product of the first 2 steps that is beneficial to future plant growth in the soil. More information on humus basics.


What are beginner urban farmers doing wrong with fertilizer and nutrition?


The starting point always, the first mineral, the tracker of all minerals, the most important mineral in humans and animals and the soil and the plant is calcium, and it’s the biggest thing that most people are doing wrong, they don’t get their calcium right, and the starting point for that: very simply, you get a pH strip, I'll explain how that works and the relationship with pH.

The first thing you do if you’re a beginner, you get some little pH strips that you can buy from pool shops, they cost a dollar or so, and you get demineralized or deionized water (DI water), has to be water that has no ions in it, you can buy drinking water that is Deionized or demineralized or distilled, and you take half distilled water and half soil, you mix it up, shake it together and wait 5 minutes, and then you dip your pH strip in, and
your pH will tell you everything (just about) all you need to know about your minerals.

If you’re going to be eating nutrient dense food that is healthy, and tastes good, it’s just a huge starting point, everything that is most edible has a pH of 6.4 and that is what is you’re looking for, in an urban farming situation, most beginners see less flavors and less extended shelf life without proper pH, but all they need is a pH of 6.4. 

What governs pH most commonly, the most important metal, is calcium, if you don’t do your calcium right, if you ignore it, often, the pH is (around) 5.4, then you need some lime, you need to add some limestone, (in this example) you have too much acid, and most home gardens are (too acidic), you’re not going to absorb as much nutrition, you are going to have issues with your plant nutrition and so the starting point is you always need to correct your (soil) pH.

So that is point number one, and that (example) involves, lime, you know, limestone, you can buy that in a bag from a garden shop or whatever, but you gotta put some calcium out there, because calcium governs cell strength - two things it does - it literally governs the uptake of other minerals, but it also governs the strength of the cell wall, and if its got a weak cell wall, then disease organisms can drill through to get into the yoke to get to the center of the cell, stem strength is about cell wall strength, insects like something
that’s got a weak cell wall strength so that they can chomp at it easily, so the starting point is getting calcium right, and that's the thing I see most commonly – (the mistake) most commonly forgotten about.


Calcium as you said is the most important of the 74 minerals, right?


G: Yes, it’s the single most important starting point for everything.


So just to re-state we need to make sure the calcium is not deficient, we need to take the pH of the soil, we need compost for the microbes. Those are the first two steps (mineral balance and microbes)? 

G: Yes, the first of them was minerals and mineral balance, the starting point for that is calcium, then you try and get  hold of a fertilizer that has trace minerals, you can do a soil test, and the soil test will tell you whatever you are deficient in, say if you are deficient in Zinc or deficient  in Boron and you are deficient in Magnesium or whatever, and you can add these things separately or sometimes in blends together, but you need to put them in.

It can be about 50$ but it’s the best investment you will ever make is to do a soil test covering all the traceminerals and address whatever your tracking, most people don’t do that and it’s just like driving bland, it’s like hopping into a motor vehicle and driving down the highway with a blindfold on because you have no idea what you’re doing unless you’ve done soil testing and you know what’s lacking and you correct what’s lacking. To do this thing properly and to have fun doing it you have to know what you’re doing.

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4. So could you talk a little bit about, what would the most basic urban farming project look like in your mind as far as, like, what type of crop you would grow and obviously we
talked about kind of preparing the soil, and that side of the planning. 

G: So the starting point was that you’re going to take your pH, you’re going to correct your calcium, then your soil test, and you’re going to correct whatever is lacking, which is simple enough to do, you can buy all the minerals sometimes in blends, that's the mineral side, then you have got to do the microbial side, which means that you need to do some compost,  the usual thing, and can use something like soil fertilizer, which feeds the soil.

If you got the soil, if there is a little gap, you get a little recipe and put on a soil fertilizer that feeds and can fire-up the soil life because they’ve got all that (nutrient) to eat, and
the insects won’t come back and all the visible things come back, and all the invisible
parts of the soil (excerpt deleted for clarity) then you can buy packets of seeds at the garden store, and that’s part of the preparation before you start (growing). 

But then when you start growing the idea is to have as much diversity as possible, the big movement now is toward (growing multiple crops), you want to have grains, you want to have herbs, you want to have tomatoes, and pumpkins and basically everything you can
fit onto that block, is the idea.

It’s a movement away from the traditional food production (model) which is all about monoculture and monoculture creates, you know, attracts the pests and attracts the diseases because nature was never about monoculture, nature was about biodiversity, and so when we do the urban agriculture model we want to have all of that biodiversity present.

We want legumes mixed in with our other crops because they serve a purpose and plants love each other, the more plants there are together, the better those plants do and the
healthier they are because the plants actually support each other. And so, the model that you can, that makes it profitable, is a model called community sponsored agriculture, which is practiced all over the world now, and in that model you produce a whole variety of things and you sell your whole box each week. You might have 100 boxes per week if you work 2-3 acres.

But whatever scale you are, you need to have your complete diversity, and you always do better if you have (this set up). Once you have (an urban farm) set up, if you look after
the minerals, and the microbes, by adding some compost and so forth, and start building the humus, and then include a whole variety of species in there, you know, you sort of got the recipe to make that whole thing  a success.

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5: Right, so, what do you think is the biggest misconception with regards to fertilizer for people just starting out, just not using it at all, or using the wrong kind?

The thing is that, people, when they think about fertilizer they sort of think about it like its chemicals, but most fertilizers are just minerals, there are some that are not good, there are certain things like, some fertilizers contain something called potassium chloride, for example(excerpt edited for clarity), and that’s really bad, it shouldn’t be in your fertilizer, it has a very very high salt index, and the chloride, the mineral called chloride, component, actually converts to chlorine, and chlorine's what you put in your swimming pool to kill
disease organisms, well it does the same thing in your soil, but you’re growing organisms in your soil, so you don’t want to use what you would call a chemical fertilizer that contains potassium chloride, of course, Potassium is a very important mineral, if you grow tomatoes, you can’t really grow them without adding some potassium. You’re going to have very very small crops unless you’ve added potassium, but the form that you use, always, is called potassium sulfate. Every urban garden should have some bags of potassium sulfate on hand.

Even if they are not doing tomatoes?

Well everything needs potassium, but tomatoes and potatoes are the two heaviest of potassium users, but everything needs some potassium.

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6. How much would you estimate you can increase yield or the weight of your crop when you harvest by engaging in these best practices?


You can quadruple, five, six, seven times more - no trouble at all, yes, and to answer one of your questions, well why do you need the fertilizer?

Plants out in the wild seem to do ok right? well it’s not really the case, if you look at, you know, anything grown in the wild, like a wild tomato, and you look at its yield, if you’re trying to make money, if you're trying to make a living (growing) from urban farming, the idea is to have optimum nutrition for that plant, to have everything correct in the soil, and then you’re going to have really great yields, and make some good money, and have healthy plants that you don’t need to stress about.

Insects show up when the plant is lacking in nutrition, and the whole idea is to take care of the nutrition and you will have much more fun and lot less stress.


So is it as simple as insects being attracted by less nutrition or is the pest problem more

complicated than that?

Well, the scientists have probably demonstrated the reason for insects in the great scheme of things and what I call the “Perfect blueprint” which is what nature is, and there’s a professor called Phil Callahan and what he showed us in a very famous book called Tuning into nature is that the feelers on insects aren’t feelers at all they are actually really complex antennae that really make a television look like a kindergarten toy, when you see it blown up, and that insects uses their antennae to pick up a variety of different signals, to pick up pheromones, for example, to know when to mate with another insect but most importantly, Phil Callahan discovered that plants emit infrared radiation, he
wrote this book 25 years ago of course, and we couldn’t film it, but now of course we can film the infrared radiation coming off crops.

But a (plant with) healthy minerals, good calcium, good trace minerals, a truly healthy mineralized plant emits a steady flow of infrared radiation, but unbalanced plants where you have neglected the calcium, you’ve neglected trace minerals, or the potassium, sends out a staccato flow, and the insects antennae pick up the steady flow and the insect flies over and says “no that’s not my role in the scheme of things”, but an unbalanced plant, a crop where you haven’t taken care of the nutrition, sends out a staccato flow and the insect says “yes that’s my job” and it comes and attacks that plant because that’s it role it’s the garbage collector on the planet, and that was Phil’s discovery, the role of insects, the reason God put them there, is because they take out the garbage and improve the overall gene pool and garbage is about not providing nutrition.


So the goal is to provide the nutrition to the plant and create something that’s not garbage and you don’t have the insect pressure, and it really is as simple as that.


When it comes to
getting rid of the insects or reducing risk the nutrition of the plant is the main goal, what are some helpful tools for beginner urban farmers relevant to this issue?  

That’s the main goal, and you can check that with a very simple tool, and your urban farmers should all go online to eBay and buy the tool, you can buy them for about 30$, it’s called a refractometer, you need to squeeze a little juice out of the leaf of whatever vegetable your growing (whichever part you plan to actually eat) and you put that little bit of drop on the face of this little sort of telescope, and you look up, and you measure the light that refracts through, the dissolved soluble solids, so what you’re measuring is “how well you are doing with your nutrition, how good of a grower are you?” and this is called brix levels, if you can keep above 12 through the whole season you don’t have any insect pressure, but a lot of people will check their produce and brix is only 3 or 4, it means they are lacking (proper) nutrition.

There are (a  few) crops that are less than that (minimum brix level), the root crops like carrots and potatoes only need to be 8 or higher, but the minimum is 8, 8 degrees brix it’s
called, but anything below that is when insects arrive. So that is a very good guideline to see if you are on the right track - it’s a very good measure and you will know immediately, you will see that response when the insects stay away, it’s a very very  strong guideline.

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7. You mentioned that a
refractometer was a great tool for urban farmers, and you also mentioned the soil analyzer, for the deficiencies in the minerals, are those the most basic tools?

So those two things together, they will give you a very good handle on your nutrition, so if you take care of both of those things it’s a great start.

Can you think of any other tools that are necessary (for nutrition)?

Well, yes, one of the greatest tools during growing is to use foliar spraying, and the best tool for doing that for an urban farm, because you don’t want to be pumping anything because it’s going to be too difficult (in a small space), the best tool is called - it comes from Germany, the company is called Stihl, S-T-H ,I cant remember how you spell, I-H-L, its a very well-known German company that makes a blow-mister, it’s a moisturizing machine that has a big solid pipe on it, and it can, on full power, can blow up to ten meters, it just makes a very very fine mist, now the secret to follow when you’re fertilizing plants, when you put in the fertilizer on through the leaf, the secret is it must be a mist, and the mist must be on the underside of the leaf because that is where, under the leaf, are the little tiny mouths called stomata, stomata are the main entry point, they actually break down CO2 for photosynthesis, but they also, if you can get into that entry point of the  plant, you will get an immediate response (from the fertilizer), so you need to aim for the underside of the leaves, when you use a little blow mister you get the other side of the leaf and you can do it very very quickly, you can do the entire (set of plants) with fertilizer
liquids, you can get these fertilizer liquids with everything (all minerals), but another thing, tremendously valuable is seaweed, (also called) kelp, so liquid seaweed is a high quality fertilizer, it contains the whole spectrum, all 74 minerals are found in the ocean and all 74 minerals are found in seaweed, and it also contains very high levels of natural plant growth promoters, (excerpt deleted for clarity) it (seaweed) has the most minerals in the ocean to build huge numbers (of nutrients), it has 40x the growth stimulants compared to a plant on the ground. So you take that gift from the ocean, put it in your sprayer and spray it all over your crop, and you can just get a tremendous response, the brix levels lift, the plant yield increases, the plant health increases, and your fun increases when  you’re urban farming. 

(For example), if you are doing you’re brix level with your 30$ refractometer and you find that it (the brix) is down, well the fastest way to fix that is apply more fertilizer, something like kelp or liquid fish is another good thing from the ocean with the whole spectrum of minerals and quite a lot of nitrogen, it’s a nice natural way of supplying nitrogen, all of those fertilizers will have 10x sometimes 12x more nutrition than in the soil, it’s just a direct pathway (to spray) onto the plant, direct onto the leaf of the plant always in a fine mist form, otherwise it can’t work.


It has to be a tiny particle like a mist to get into that little area called the stomata to get under the leaf and into the plant, so that’s a few hints that you’ve got, next get the pH strip from a pool shop, mix half water half soil, 5 minutes, dip it in, and check and you need to be 6.4 pH, go onto eBay, buy a 30$ refractometer
to monitor your crop, you can go online to get a soil test labs, get a good soil tester that will covers all trace minerals.


That will cost about 30$, those are the sort of investments  that are essential if you want to get it right from the start you use compost, and soil fertilizer and foliar fertilizer and that little recipe, can be very very profitable, so if you get it right, you will get very excited because it just changes everything.

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8: I
nvolving the new wave of hydroponic growing and new alternate growing mediums, can you talk about how the cultivation process changes with those different mediums?

There’s a really major problem, I know that a lot of critical thinkers have written about this and so forth, how hydroponics is not a good way to produce food, the main reason is because with hydroponics, the plant needs two forms of nitrogen: one is called the ammonium form and one is called the nitrate form:  a healthy, well balanced  (plant) with great flavors and so forth has 3 parts ammonium and 1 part nitrate, that’s the natural scheme of things, which is how healthy plants should be, but (with pure hydroponics) you
have a high percentages of nitrates, there is no natural ammonium nitrogen at all. Now in the soil there are organisms that can fix nitrogen from the atmosphere and give you a
lot more ammonium nitrogen, via that pathway, by fixing it out of the atmosphere and into natural ammonium nitrogen in the soil.

That doesn’t happen in hydroponics where you have got only nitrates, nitrates are actually carcinogens, there are 200 published papers linking nitrates to cancer, so hydroponic food, because it is only using nitrates, the brix levels, you know, when you
are measuring how healthy the food is (is low), for example, a good lettuce grown in the soil should have a brix level of 12 to 14.

We have never found hydroponic lettuce anywhere in the world, with a brix level higher than 1.5. Its rubbish food that you shouldn’t be consuming, it’s toxic food. Now when we talk about hydroponics, now, hydroponics is a really bad way to produce food, but if you change that and we talk about aquaponics, that’s a whole different story, Aquaponics is using the ammonium nitrogen from the fish waste that goes through and becomes part of the nitrogen for the crops and you can produce great food with aquaponics, but pretty ordinary food, pretty poor food with hydroponics, so aquaponics involves fish part of step, but hydroponics is not a good way to produce food.


What about other soil-less growing mediums?


Other soil-less mediums are fine if you have got your nutrition, if you are using things like liquid fish and some kelp and you’re running it through into the (growing) medium, you can get great tasting food, and some of the big berry growers are using substrate, just mediums using coconut peat and other things and you can use really good organic nutrients that run through them and produce really good quality crops so that is fine you
are usually going to use peat or coconut fiber or perlite or any of those mediums that just adds nutrition, but you’ve just got to make sure the nutrition is not just the hydroponic  form, you have got to use things like fish and kelp and some of these combined trace minerals and so forth. There are lots of big scale blueberry growers who are doing that
for example and producing beautiful foods, high brix and really healthy plants so there’s nothing wrong with that if you do it right.

So to clarify when we’re talking about the bad kind of hydroponic growing system: it’s essentially the kind without any fish components or without the proper nutrients, the kelp, coconut fiber, other type of growing mediums, etc.

It’s when you use just the water base and you grow into that water that just has the chemical fertilizers in it. That’s what you have with conventional hydroponics, there are ways that you can do it (hydroponic urban farming with nutrient rich crops) what you need to do then is bring in all those natural forms of nutrition and then it changes. For example, you can put compost tea or you can put worm juice into the water, you can do all of those sorts of things and then you can kind of change kind of conventional hydroponics
and then it will be a lot better.

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9. Obviously  you know so much more about urban farming than many of the people that will read this could ever hope to know about in the near future, what are some books that you think are full of helpful information that a new person could understand, maybe one or two recommendations?


There is a wonderful book called The farm as an ecosystem written by a man who is no longer with us unfortunately, called Jerry Brunetti, it’s on Amazon and so forth, that’s
probably the best sort of book that covers the  whole story in depth from the beginner right on up to an advanced grower. 


Great, and a
little bit more about Nutri-Tech, for people who are looking to get the best fertilizer out there, is Nutri-Tech Systems a good choice for beginners? What are details on your products, what are the best products for beginners, and where do they go to find them?

That is the problem because we only have some of the (large scale) agricultural product over in the US , if there is anyone out there who wants to bring out a revolutionary sort 
of home garden range, we have our Life Force (farming) box, but it’s currently not available, its actually just a three step program that makes it very simple, it’s almost like gardening for dummies, if you do these 3 things, there’s two parts to each step (in the program), its almost impossible to fail but you can only source that product in Australia or other countries where they’re available and that’s  not the US, unfortunately.

We do have many people
not just in the US but across many different countries that read this website, so you never know. 

G: We’re looking for distributors for the home garden  range you can check it out by looking at the home garden website but we are certainly keen to get it out there because it is something unlike anything that is available anywhere in the world, we have taken
all that we have learned from intensive food production on a large scale from around the world and we have  put it into new things in the home garden that really haven’t been available before we even have microbes that you brew up in a bucket and 
so forth to really get your soil (healthy), so were looking for distributors out there (US) if anyone is interested - the website is nutritiongardening.com.au it will show you the all
things that we do in this field.

Sure, so I think that is pretty much all that we have, thanks so much Graeme!

Graeme Sait is the founder of Nutri-tech Solutions, an Australia based company specializing in animal, plant, and soil nutrition with operations in over 55 countries. He has given TED talks on soil nutrition and is one of the foremost thinkers in sustainable food systems in the world.

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