What elements does a plant need to grow?
github.com
github.com
This is a fair amount of work, and I'd guess that relatively few non-professional growers would bother. I hope this may be interesting to anyone generally curious about plant nutrition though, or about the design of modern complete chemical fertilizers.
https://old.reddit.com/r/Hydroponics/comments/o8j68n/singleb...
That was still with the old commercially-blended nutrients, though. I've so far used my custom blend only for a few bok choy, as a final quality control check since they're fast-growing. If those continue to look good, then I'll move my entire balcony to the custom blend in about a month.
All of the i/o is dumb, the control loops are all on the node-red flowgraph allowing for lots of visibility of terms when tuning pids.
The node-red dashboard lets you mix telemetry and control on a very touch friendly format, and i spool all of it to influxdb to compare runs over time.
I’m sure you’ve got what you need with what you’ve built but at a minimum node-red might be worth a look. I was suuuper impressed using it for this.
The architecture is pretty straightforward. MQTT over wifi acts as a message bus between node-red and your 'legos'. (You don't really even need a raspberry pi, you just need to be able to run node-red, an mqtt broker and have wifi. I ran everything from containers on raspberry pi and ran the pi in AP mode which kept everything self-contained and tidy.)
For the i/o 'legos', i had more luck with the esp8266 than esp32's on Tasmota, but things have probably improved since then. You could also look at espurna, esphome, home assistant, etc. Main thing to look for is a firmware that supports some kind of async messaging protocol that nodered supports and has the i/o you need. You can buy a six pack of nodemcu esp8266's for $20 off amazon.
Good luck and have fun!
What climate zone are you in (if you don't mind me asking)?
I'll be growing a bunch of things in Spring and would like to make a setup like this. I'll keep an eye on the project and likely contribute if you're open to it
Mostly inadequate pruning, I think--I was planning to replace it soon, so I'd gotten lazy. Normally I remove side shoots and lower leaves, for less foliage and better yield. The fertilizer was Masterblend 4-18-38, which is intended for tomatoes and pretty close to the University of Florida's "Stage 5" tomato profile (per their article linked from my calculator). So I'd guess the nutrient profile was close to optimal, except for all the excess phosphate from my pH down.
I'm on a somewhat protected balcony in San Jose, USDA Zone 9B. That's warm enough that I can grow tomatoes through the whole winter, as long as it's a cold-tolerant cultivar (e.g. Early Girl; or Sub-Arctic Plenty, which is a determinate so needs less/no pruning), and lots of other stuff too.
And contributions definitely welcomed, especially on the controller firmware. That's currently in a state that's useful only to programmers. More work there (integration with home automation software, a nice browser-based interface to schedule irrigation and dosing, etc.) would make that accessible to a lot more people.
- How do you find the best concentration for each nutrients for a given plant? I usually just make general-purpose mix with General Hydro but I see that your calculator includes some presets for specific plants.
- I see that your board includes pH and EC probes. I always wanted those in my setup but I've read that they tend to degrade fast. In your experience is that true?
- Where did you get the potassium nitrate? I always wanted to make my own mix but I've heard that buying large amounts online will put you on a list as it's a strong oxidizer (you can make explosives with it).
It starts with simply observing the plants. You can vary the dosage from crop to crop or between plants in the same crop. Plants with leaf tip burn will generally have too high of a concentration and plants with pale leaves will generally not have enough nutrients. This assumes other factors like pH are correct.
Another option is leaf/flower/fruit analysis. For example, if you're growing spinach, you may view iron content as an indicator of quality, healthy plants. Determining the iron content of the leaves from plants dosed at different rates will help zero in on the optimum fertilizer program.
The best way, IMO, is to test the nutrient solution before and after it has been "fed" to the plants. This requires a recirculating system for best accuracy, but runoff can also be collected in a drain to waist system. As the author mentioned, unused nutrients will build up in the solution. An ideal solution will have the nutrients used by the plants at the same ratio they are found in the virgin solution. Any skew from that over time will indicate which concentrations should be adjusted and by how much. It can be a tricky beast, however, as the uptake rate of any individual nutrient is influenced by the presence of other nutrients. Change one and you may create an imbalance elsewhere. Like most things, it's a process.
https://cdnmedia.eurofins.com/corporate-eurofins/media/12142...
but I suspect from the author's bio that it's trustworthy.
For probes, see
https://github.com/hydromisc/hydromisc/blob/master/doc/senso...
EC probes should last basically forever if correctly excited (zero net DC). pH probes are consumables, but my $10 probe is still happy after a year continuously immersed. As process fluids go, hydroponic solution is pretty mild, neutral-ish pH and decent ionic content.
I bought the potassium nitrate from MBFerts in combination with other fertilizer salts, so if I'm on a list it's probably "cannabis growers" and not "mad bombers". If you'd rather not use it, then a quick experiment in the calculator shows you can still hit a decent profile with just calcium and magnesium nitrates.
Do you know if there are any benefits of growing hydroponically compared to the conventional (farming) methods? Is it economically interesting? Is it more sustainable?
Time to harvest is typically 2-3x less / faster.
Yields are 2-3x in volume (targeted nutrients, more hours of "sun")
Can grow small without a yard (ie Condo, Apartment, Townhouse)
(https://www.trees.com/gardening-and-landscaping/advantages-d...)
Takes ~2 weeks to 1st Harvest, lives on a bookshelf in my living room, 6 plants produce a salad for 2 about 1x a week. Lettuce is flavorful. I expect a single "planting" to last about 4 months (having done this a few times)
In comparison to my outdoor winter crops (including Kale and Broccoli) , all planted around October 7th; Outdoor Kale and Broccoli aren't to first Harvest yet (estimated ~60 days)
I once used an inexpensive electrical TDS meter (total dissolved solids) to track the amount of non-organic solids in water both before and after filtering over time. My goal was to determine the rate at which to replace the filter, and it turned out the manufacturer's recommendation was perfect. However I did notice that the unfiltered water's measurement fluctuated a lot over time. Could that pose a challenge in your scenario?
Thanks for a great read, btw.
A single well may also show gradual seasonality, like from snowmelt and such. I assume that's happening too, but in my current setup that would be hard to distinguish from gradual pH variation due to changes in the plant nutrient uptake.
Also, I was under the impression that there are two stages for plant growth: vegetation and fruiting. The two stages have different requirements for nutrients:
- high nitrogen, mid phosphorus, low potassium; and - low nitrogen, mid-high phosphorus, super high potassium
respectively. Do you use the same mixture for both stages?
I believe that professionally, RO isn't used to solve excess calcium, carbonate, sulfate, etc., since it's cheaper just to neutralize the carbonate with acid and adjust the fertilizer salts appropriately. RO is used to solve excess sodium, chloride, etc., since the source water is already above the final desired concentrations.
I'm running a single nutrient profile for all my plants, regardless of life stage--I can scale all the element concentrations together, but I can't adjust the ratios. My yields would be better if I adjusted as you say, though. At some point I should add a third fertilizer part and dosing pump.
With that said, living soil is not practical for everyone. Trying to do it indoors where you also live could create issues if you do not have a good IPM strategy, and fully understand the soil food web. "Teaming with Microbes" by Jeff Lowenfels is an excellent book to learn about how the soil food web works.
In my case that's a feature and not a bug of soil-grown marijuana. I'm way more of lightweight compared to my college days and would prefer good taste over potency.
Finding the right combination of these elements is what hydroponics farmers do everyday, pushing the limits of their crop for maximum quality/yield. We are starting to see a big shift in hydroponic fertilizers from liquid to powder since nobody wants to pay for shipping water.
I highly recommend https://github.com/kizniche/Mycodo for anyone doing anything in hydroponics.
https://agrilifeextension.tamu.edu/library/gardening/essenti...
Interestingly none of the critical semiconductor elements are required by plants: Silicon, Germanium, Gallium, Tin, Gold, Silver…
Ehm. Check out this Nature article on the importance of Carbon:
https://www.nature.com/scitable/knowledge/library/effects-of...
Very readable and worth reading in full. Especially the effects of elevated CO₂ on the C₃/C₄ photosynthetic pathway and crop yields.
The primary constraint is maintaining low enough CO2 levels to remain healthy for the humans that work inside the greenhouse. Plants themselves can handle very high levels of carbon dioxide.
If you would like that to stop happening, I would suggest working on a ban on petroleum drilling, or a carbon tax.
Yeah, absolutely. I tend to grow a lot of different plants at different life stages, so an optimal profile for each one would be a lot of work. I'm certainly paying a cost in yield for my laziness, though.
At some point I should redesign my nutrients into three parts. I've got support for a fourth dosing channel (fertilizer A, fertilizer B, pH, spare) in my electronics, so it's just another pump and the plumbing.
Found a source that discusses its use [0], apparently is has beneficial hormones as well, "Besides its nutritional role, coconut water also appears to have growth regulatory properties, e.g., cytokinin-type activity"
Amateur hydroponic growers often use reverse osmosis water, somewhat wasteful but cheaper than distilled. You can get RO systems designed for aquarium use with no pressure tank at the output and just let them slowly fill a barrel or tote, over hours or days.
Orchids for instance can be artificially bloomed with phosphorus but if it was dormant people would just think it’s dying, as if natural cycles of less bloom was a failure of the plant’s growth!
Sulfuric acid is not really that dangerous unless you are getting the high test stuff from a chemical supplier. You can use battery acid refill solution, it's just deionized water and H2SO4 at around 30% concentration. That's mild enough that it won't cause any immediate burns, but you should still wear gloves and goggles when handling it.
There's no need for nitric acid, since you are already supplying nitrate ions.
Sulfuric acid would give me excess sulfate, but since the plants aren't too sensitive to that I expect that would be an improvement over my current excess phosphate. I'm not sure if I'd get calcium sulfate precipitation as the reservoir concentrated. Nitric acid would let me hit my target profile exactly (with a corresponding decrease in nitrate salts), but it's way more dangerous. I've seen nitric acid used in academic trials and in countries with weaker safety laws, but not commercially in the USA.
I mean I bet nitric acid would work great for that purpose, it's just a bit more expensive and harder to get in some places, as you mention. It's definitely commercially available in the USA though.
Duda diesel has it: https://www.dudadiesel.com/search.php?query=nitric
Duda also has sulfuric which is likely higher purity, but you seemed to express some concerns about working with corrosives.
I'm a former chemist, so anything short of super angry chemicals like piranha solution, I'm not too phased :D
Idiocracy
I would totally buy a Brawndo hydroponic formulation.
My next thought was, can't you take the plant out of the equation too? How difficult is it to rearrange these nutrients from a fertilizer mix straight into something resembling animal proteins (though easier for humans to digest)? I wonder at what point plants scale better than raw conversion of fertilizer to whatever protein these companies seem to be synthesizing.
Yeah, though with the caveat that if your medium retains water very effectively (as e.g. rockwool does) and is exposed to light, then it may grow algae. The larvae then feed on that algae, and the problem is back.
I spend a lot of time fighting fungus gnats. The best option is always to adjust growing conditions to create an inhospitable environment for them, but I also make recourse to Bti (a bacterial toxin, like mosquito dunks) or pyrethrin sometimes.
But any should work just fine
[1] https://growx.ru/images/catalog/GHE/stimylatori_i_dobavki/su...
This is very useful and I want to say a big thank you to the author for doing so much of the work I was planning to do!
For those wondering, it stands for "Nutrient Film Technique" and it's basically running a small stream of nutrient solution in PVC tubes with your plants' roots being somewhat submerged.
It's a pretty water-efficient technique, this link explains it well: https://www.trees.com/gardening-and-landscaping/nutrient-fil...
In my layman's mind, having agriculture right next to roads is bad because vehicles are dirty.
Recently, someone told that's not the case because "plants need this stuff". Any truth to that claim? I'm yet to read the article
Also I was told to never eat berries growing from a bush close to a road since they are more dirty.
Nowadays not so much. Specifically around 200 times less so. Not worth consideration.
Whatever comes from the road is usually baked by the sun, so no nutrients left there. No need for that.
I can't come up with another way of analysis for this claim without it being more specific, but generally, no, that's not working today.
The only issue is about the effects of these elements and what they can do to the water or your home. Would they need a special environment to prevent fungi, algae, bacteria or mold that would also feast upon these nutrients? You said bacteria didn’t always appear but what if some will grow on hydro? What optimizations would you do for preventing infections?
Algae can use the same nutrients as the plants, but can often be controlled by excluding light. Other bad microbes are generally heterotrophs, so they're feeding on something else (like dead algae or dead roots).
I don't think there's much about plant hormone use that's specific to hydroponics. People use rooting hormone and foliar sprays of plant growth regulators and such, but they do that in soil too.
We get nutrition through the food we eat and there are many, many molecules that contribute to our health. This project is cool but I worry about subtle nutritional deficiencies if this food ends up being the majority of a diet.
I have the same worry when it comes to lab-grown meat.
It's possible to manipulate the element breakdown of the edible parts of the plant over a surprisingly wide range with an appropriate nutrient solution. For example, they grow low-potassium vegetables for people at risk of hyperkalemia:
https://www.mdpi.com/2311-7524/7/4/87/pdf
Of course the lab test doesn't indicate whether the elements are in a form available to humans. I'm not aware of any biochemical mechanisms by which hydroponic vegetables with the same element breakdown would be less nutritious, though I'm not sure how you'd prove none exist.
That's an extremely trace mineral.
https://www.fs.usda.gov/treesearch/pubs/46345
That's not about hydroponics, but the theory behind sophisticated growing in containers of soil-like potting mix is almost the same.
I think that like us with our microbiome, the plants have evolve with their microbiome in the soil. To grow them from a chemical mixture is to oversimplify nature.
Alternatively, you could use a coarse sand bed as media and ’compost’ natural fertiliser and get beneficial bacteria and fungus going.
And it's been throughly and exhaustively 'found'/demonstrated/proven that plants grow very well in hydroponic systems. And depending on the exact plant & nutrients used, can be just as nutritious, or more, or less nutritious compared to soil grown plants (also depending on how the soil plant is grown).
Natural != the best way to do it.
(note: I'm not saying bacteria/fungi can't be beneficial)