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Comment by FredPret | Hacker News Reader

I’ve always been super pumped about hydroponics and the absurd yields you can get from it. Hopefully it gets cheaper and cheaper over time.

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Hydroponics are limited to low-calorie foods such as lettuce, herbs, spinach etc due to constraints in the method itself. High calorie and/or high fiber foods require complex rhizospheres which is currently only found in healthy soil.

To add injury, the substrate used to provide nutrients to hydroponic plants either require petrochemicals or other plant material (compost, husks, seeds...) to mimic a complete nutrient profile.

Perhaps there are solvable problems, but given the already high costs and limitations, hydro is not an option if our ecosystems collapse.

> High calorie and/or high fiber foods require complex rhizospheres which is currently only found in healthy soil.

What is your source for this claim? Major grains (wheat, corn, rice, etc.) grow fine hydroponically--I've actually seen modern conventional agriculture described derisively as a hydroponic system using the sterilized natural soil as its inert medium. That description seems basically correct to me, though I don't think it's necessarily bad. Production of grains in systems analogous to hydroponic vegetable production would certainly be possible, just currently uneconomic:

https://www.pnas.org/doi/10.1073/pnas.2002655117

The major benefit of hydroponics is in achieving very high yield per acre. This is important e.g. when growing perishable vegetables in expensive greenhouses near densely-populated areas. For grains that are readily dried, stored, and shipped, it's currently far cheaper to cultivate more acres in remote areas at lower yield per acre.

The "petrochemical" claim is also confusing. The point of hydroponics is that the plant gets nutrients from the solution, not from the inert substrate. Typical hydroponic substrates may be plant-based (e.g. coir) or not (e.g. rockwool), but in neither case are they providing significant fertility, nor making significant use of petrochemicals. Obviously their energy inputs for production and transportation often come from petroleum; but that's true for almost any human activity today, including organic agriculture. A few niche applications do use petrochemical-based substrates (e.g. phenolic foam), but very rarely.

The synthetic nitrogen fertilizers dissolved in the nutrient solution often use hydrogen from natural gas, since that's the cheapest source, but could use any other source of hydrogen (e.g., electrolysis of water) instead. Here's an article studying those economics:

https://www.frontiersin.org/articles/10.3389/fenrg.2021.5808...

>Hydroponics are limited to low-calorie foods such as lettuce, herbs, spinach etc due to constraints in the method itself.

Why do you say that? Hydroponic setups often produce tomatoes, peppers, eggplants, strawberries, etc are all quite popular.

https://www.biotecharticles.com/Agriculture-Article/Hydropon...

>High calorie and/or high fiber foods require complex rhizospheres which is currently only found in healthy soil.

Mainly root veggies or large things that are unruly like a watermelon. More of a practicality problem. I have been eyeing that root veg drip hydroponic system. You can absolutely grow all the foods hydroponically. Not sure about those rhizospheres.

>To add injury, the substrate used to provide nutrients to hydroponic plants either require petrochemicals or other plant material (compost, husks, seeds...) to mimic a complete nutrient profile.

This hasn't been true for decades. I think you touched on the real big problem "petrochemicals". Oh ya we just found the problem.

https://ntrs.nasa.gov/api/citations/19900009537/downloads/19...

>Perhaps there are solvable problems, but given the already high costs and limitations, hydro is not an option if our ecosystems collapse.

Did you know when you exclude the illegally seized Moroccan fertilizer we have about 20 years left of current day farming?

I wonder about glyosophates eh.

Hydroponics only makes sense for high price crops like salad or vegetables which make up only small amounts of agriculture. It’s way too expensive for the crops that provide most of the calories consumed by humans or animal feed: wheat, maize, soy

> Hydroponics only makes sense for high price crops like salad or vegetables

That's only true if it's in the city or other location with high cost/sqft land

imagine if we can reclaim all the land that salad and veggies use and replace it with good grains?

solutions aren't always mutually exclusive.

... that'll be a drop in the bucket. cereal grains alone use more than 10x [1] the amount of land used for vegetables. Add in other large users (coarse grain / oil crops) and it's over 20x, meaning you'd get like a 5% increase by replacing all vegetable land with grains.

[1] https://ourworldindata.org/land-use#land-use-by-crop

thanks for sharing, thats pretty good data.

can't disagree with that. seems like even more reason to not use the land for things that can be grown vertically/hydroponically.

But definitely something i'll be reading more on, thanks for the resource.

It wouldn't be particularly nutritionally useful, and you'd be able to grow grain for a couple of years before your soil turned into dust.

That's why America starved in the 1930s.

Ahhh, a reductionist solution that erases cultural heritage while solving no meaningful problem. How original!

Animal feed, along with fresh water and land usage is a major issue, as you have suggested.

Less animals for human consumption = less feed, water and land required for animals. This opens up resources and agricultural land for vertical farming specifically for human consumption.

Humans currently consume 55% of the calories from agriculture, with animals at 36% and the rest for biofuels.

https://www.vox.com/2014/8/21/6053187/cropland-map-food-fuel...

Water usage is an exaggerated concern because people misuse statistics.

There are places where water usage _is not a concern at all_. In Iowa we take rainwater and pipe it to rivers faster, the opposite of irrigation. A gallon of fresh water "saved" in agriculture in Iowa is meaningless. More than is necessary comes from the sky.

Water usage is a problem where people are trying to grow things where there isn't enough water (i.e. much of California), in those places agriculture needs to be more selective about what it grows and needs to grow less as to not overburden water sources.

In Iowa though half the state would be standing water much of the year if we didn't actively drain our fields, griping about how much water growing corn "uses" is absurd in that situation.

Yes, but dumping oil based fertilizer on fields to produce government subsidized "biofuel" is still ridiculously stupid.

Rainwater isn't the only form of water, farmers in Iowa pump groundwater too, and those aquifers are becoming seriously depleted in a lot of the plains states. This is causing pretty serious drops in groundwater levels in a lot of areas and won't be sustainable indefinitely.

https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/...

https://www.usgs.gov/special-topics/water-science-school/sci...

Of the 26 million acres of farmland operated in Iowa, 152,000 acres are irrigated or 0.58% (2015). Municipal, industrial, etc. water is quite often groundwater, but the farmland is 99.5% not irrigated at all.

Okay, so if you get rid of livestock farming, what do you do with the land that is currently used for grazing and how do you cope with the inevitable soil depletion from not turning arable land over to pasture every so often?

It is cheap way to get badly tasting vegetables. There is real, huge noticeable difference between tomatoes raised via hydroponics and not. Unless they manage to make them super packed with nutrients, which they are definitely not, there is zero reason to eat them.

Hydroponics sounds great on paper. Until you see the sludge they feed the plants with. Given the incentive to cut costs, especially where it's hard to see and/or measure, not sure I want to get anywhere close to the resulting produce.

https://daily.jstor.org/a-history-of-human-waste-as-fertiliz...

This objection baffles me. Traditional agriculture has used literal feces to "feed" plants since its inception, and frequently uses bones and blood as nutrient input. I'm eating the resulting food, not the rot and excrement used to feed it.

That is a fault of imagination ;) Think "processed oil refinery sludge" or some other such industrial horror. Oh, sure, there is a shit ton of heavy metals and/or who knows what other garbage in there, but it's below the FDA limit (hello VW wink wink), so let's roll with it straight to mass human consumption.

What do you mean by "sludge"? Typical hydroponic solution just looks like water, thus the name. The fertilizers used are higher purity ("greenhouse grade", "ultra-soluble", etc.) than those applied to soil, since impurities risk clogging the fertigation equipment.

Solar Foods and similar are also promising ways to massively reduce land use

https://en.m.wikipedia.org/wiki/Solar_Foods

I work in hydroponics and when I describe it to someone new I mention it's like creating 15 acres of agricultural land out of thin air. Of course that depends on the crop, but there can be huge advantages to covered agriculture.

Is it still mostly salads or is there hope for high-calorie hydroponics?

All depends on the cost of the land it's on, electricity/water costs, the growing apparatus, whether it requires artificial light, and what the market rates for the crop are. So yeah, there's a lot of variables as one could imagine.

It's still mostly salads.

> I mention it's like creating 15 acres of agricultural land out of thin air.

So you can just grow things hydroponically out of nothing? You don't need masses of petrochemical-derived fertilisers and plastics?

Hydroponics are starting to sound like perpetual motion machines, where you can get more calories out than you put in.

It kinda works for farmland because it’s basically solar panels as plants.

I know, right? And if you've got farmland you can't easily put plants on you can put animals on that instead, and eat the animals and use the stuff the animals leave behind to grow plants.

It's almost like an ecosystem that has worked for hundreds of thousands of years is actually a pretty solid idea.

Modern hydroponics are certainly not perpetual motion machines. The difference is that you can collect all of the unused nutrients below the plant and recycle them back into the input stream. Secondly, you can elevate the carbon dioxide levels because it's an enclosed system and encourage plants to grow faster. Finally, the enclosed nature more easily permits integrated pest management, which reduces total pesticide requirements...of course, herbicides are not required at all because of the way hydroponics grow.

It's not perfect, but it's exceptionally more productive than field agriculture.

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