Backyard Aquaponics
A place to discuss aquaponics

OK, so I've read that a 42 sqm vegie plot in the dirt, properly rotated etc etc etc, will feed a family of 4 for a year and onwards....

So, if one was choosing AP instead of dirt, what sort of size comparison would you make??
I'm talking growbed quantities, not floorspace, assuming some sort of vertical thing going on too - as in, perhaps blue barrels, double stacked in a greenhouse??
I guess I'm after any stats that might be around regarding the extra efficiency one gets out of AP compared to dirt, so I make sure I plan it all right....

TIA
Ali

have you got a link on that 42sqm? i'm dubious it'd feed a family of 4. supply is the issue, not everything is going to fruit when you want it to.

the advantage a dirt garden has is you can use proper pesticides, which means less spoiled produce, a huge problem with ap when your talking about feeding a family.

but i'd say if you worked at it and managed to keep the pests out, 40sqm of ap grow beds could produce a huge amount of food with the advantage of very little water use. it also trumps the dirt with the fact it comes with fish to eat.

OOOh the 42sqm is from the diggers catalogue - no pesticides, it's all organic, and based around planting with staggered times etc etc to try and keep crops of some type going throughout the year. Obviously involves eating seasonally as well.

yeah keeping pests out will be interesting, we've got mice all through the house at the moment - will be trying to build a mouse-proof greenhouse over the site of an old aviary bank here to put the system in - hoping that the existing concrete footings are deep enough to prevent things digging in.

all i can tell you on spacing is that i throw the packet out the window when it comes to plant spacings! the planting density is far greater in AP.

i'm sure someone else can give you a more quantitative analysis

I do not plant in rows any more so no idea, Seems in ap if it can get sun it will grow so planting density would come from that, and how easy/difficult you want to make the harvesting. Digging thru cuc vines to get to the peas. etc. Its a jungle.

Ali, Consider how you are measuring efficiency. It would appear that you are considering space, but also consider measuring water usage, effort, and money. Decide what your most important factor is. Also consider that different dirt-growing methods give different yields. I use Square Foot Gardening in my dirt garden and things are much more intensively grown.

Interestingly, my dirt garden is very close to 42sqm, and I cannot feed my family of four out of it. We do eat well in the summer, and I know that if I worked a little harder at it, I could do better. Just for fun, I cross-checked my book, "The Sustainable Vegetable Garden". According to them, if you plant only potatoes, which give the highest caloric yield per acre, and used standard Commercial Agriculture techniques, you need 1570 sqft (149 sqm) to get the calories to feed one person for the year. So your family of four needs 600sqm to eat from. And that's only potatoes. Other crops have lower caloric yields, but would provide variety and the nutrients that might not be in potatoes.

They then continue on to talk about biointensive gardening, and how much better the yields can be. They suggest a garden size of 200 sqft (19sqm) per person to bio-intensively grow food for the year. So that would come out in the range of 80 sqm for your family of four. Although I suppose that if you had young children, you could use less space. If you have teens, it better be more!

I know none of that helps you compare AP to dirt space, but it does give you the range of yields you can get just from dirt.

Another variable is time
AP growth is generally much quicker than soil, so logically a set area could produce more in same time frame.

I have found (this is with Hydroponics) that a plant still takes roughly the same amount of space in dirt or in Hydro. Of course that is all things being roughly equal. The plant still will grow to some size and unless you are really pruning and training, plants put too close together will crowd each other for space, light and air flow. Crowded plants tend to produce smaller yields so though there might be more plants the yield may be the same or even less. Also crowded plants can be more prone to certain diseases and pests depending on the climate/situation.
I only mention this because it seems to be a common belief that you can grow way more plants in Hydro in a smaller space than in dirt. The only part of this I see as being relevant is that in hydro the plants are provided with all the nutrients/water they need and the roots should not have to go searching for it. Now we all know that just because everything is provided for the plant does not meant that the roots quit growing big, otherwise we would never have issues with roots clogging up drainage!

On to another point in the thread. Amount of space needed to provide for a family of 4. I expect what is really meant is that amount of space can provide fruit/veggies for a family of 4. I've once heard that 100 sf could provide enough fruit/veggies of one person, how accurate that is I don't know since it would also depend on the climate and plant choices. If trying to provide all the food for one person, I understand there is a guy (quite skinny) surviving on what he grows on 4000 sf. He is probably growing mostly potatoes.

As to how AP compares to dirt. Hum, there are so many variables. Hopefully a few people with big systems can share what kind of yields they get from their amount of grow beds and also tell what kind of growing season and stocking density and amount of feeding of the fish they have going. I'm sure it will also vary by maturity of the system though many people with brand new systems seem happily shocked by the growth rate of new seedlings in the system. I'm sure getting peak production from a system is a great balancing act since there needs to be enough nutrients produced by the fish to support all the plants and there needs to be enough plants to use up the nutrients supplied by the fish.

Good luck in your planning ali!

Using intensive growing with hydroponics I can produce 4 pounds of vegies every day using 12 meters squared. This is enough to feed one person. Dirt is only a medium just like gravel. Now clearly it takes a whole lot more water in the ground. Also, nutrients are much harder to get into soil. Further your soil must be like Alaska humis, loaded with organic matter bacterial and fungi and aerated with worms to grow 4 pounds of vegies every day in 40 square feet. It would take 10 times as much water and 10 times more work (at least) to get the same results. Thats not counting the cost of garden equipment like tillers.

You can get the same or better results in either dirt or ponics depending on the care you give it. I did the compost and aerated bacteria tea ect for a couple years in dirt and I can tell you that I prefer hydroponic / aquaponic gardening over dirt hands down!