Soil in aquaponics

[Zac Kind]

Hey guys, first off I want to say that I love the blog and reading all the different posts.  I always find myself getting lost (in a good way) on this site, reading for hours. Ive been studying aquaponics for two years now. I live in the city of Philadelphia and build a small 200 gallon system on my roof. Its been running leak free for about a year. I love learning about aquaponics and each time I learn something new more questions arise. The other day my friend and I were working on his design at his farm. We were discussing whether or not you could have soil compost in your aquaponic system. so an inch of gravel then an inch of compost and then your plants. This system is a 4 tier system. Water starting in the fish tank and pumping up to tear one which is 15 inches wide by 10 feet long and about 8 inches tall. Each tier follows under it with a slight tilt so that the water drops to the next tier. Then till the water trickles back down to the fish tank.

Will the compost hurt the fish? Will the compost bring soil based disease to the water? Or will the compost help just like it would in a normal garden?

Thank you and looking forward to your response,
Zac

[Steve R]

So you have a few issues. You don't want to chain more than 2 beds together so one bed flowing into one other one is the most you want to do because the 3 4 5 and 6 beds wont receive any where near as much nutrients as the first 2. Some people do use peat to lower PH or as a filter but i have no experience with that but have read about it. As far as soil goes it would be fine for a duel root zone and possibly a wicking bed setup but is far from ideal unless your using a duel rootzone setup. You would be better off with clay based grow media like hydroton or raft beds. Philly has a great aquaponics community i grew up there and saw my first AP system in a local community garden in south philly. The soil will mess up not only your PH but stain teh water and generally make a huge mess. It also wont allow for enough air to get to the roots when the bed is drained and your roots will rot.

[Donald Holmes]

Zac, Soil is an excellent choice for root vegetables. Look at www.oldworldaquafarm.com. The website shows a new type self cleaning filtration adaptable to aquaponics. This filtration system will allow you to grow all types of vegetables, flowers, herbs, etc. There is minimal maintenance. The soil allows you to plant on 6 inch centers. Note the tote system with 60 tomato plants and 100 fish in it. The soil costs $1.47 a 40 pound bag at Lowes. I do not use hydroton or clay balls, gravel, or anything other than soil in my systems. I do know those items are much more expensive that soil. The same soil and water have been in these systems for more than a year. AquaFarming is the next step in sustainable food growth. Donald

[Steve R]

How do you get enough oxygen to your roots if there in flooded soil the whole time?

[Donald Holmes]

Steve, In AquaFarming the soil is not flooded. Just like nature roots grow towards water. Rain is merely a means to clean a plant so normal respiration can occur. The system is as nature is. Except nutrients are constantly added to the soil by the fish. Nitrosomona bacteria convert Nitrites (fish waste) to Nitrates (fertilizer for plants). Therefore there is no competition for nutrients and you can place plants as close as the root ball will allow. Plants of like qualities allow roots to grow together and do not compete. Plants of unlike qualities such as weeds are not allowed to grow in the same space as like plants. I realize this is new information and can be quite confusing as to what you have been taught or learned in the past. At Old World AquaFarm we study plant behavior as well as aquatic animal behavior. Please understand nature communicates. All we have to do is listen. We have 60 tomato plants and 100 fish in a 330 gallon tote system. Another system, the Pro 200 we have over 500 seedlings and 100 pounds of fish growing in 300 gallons of water. One pump (1320 gph) for each system. Donald   

[Steve R]

If that's the case how is it different from soil? If you aren't getting the flood and drain on your roots your not going to get the growth speed boost that makes hydro and aquaponics so great. I'm sure it rocks for growth but i feel like it would be much slower growth because your not getting optimal gas exchange at the roots. Unless I'm understanding this wrong this is a constant flooded bed at the bottom with soil above it like a NFT with soil in the basket. I'm sure it works great but in my experience its better to allow more of the roots to breath. I run a similar system at home where i put my plants in pots with soil on top and media on the bottom i just flood the media part instead of constant flood. Cool post thanks for sharing. 

[Donald Holmes]

Steve, You are speaking of flood and drain for the roots to breathe. I agree with you that in a rain forest there is faster growth than in a desert. There will be more nutrients in the rain forest due to more decomposition. So if one adds nutrients as in hydroponics and roots absorb those from the water then there would be a growth spurt of the plants. However there will also be an increase in the "leginess" of the plant secondary to support. That is why nature uses soil as a media (for support of the plant). The thinner the stem, the less nutrients which can travel its length for growth. Therefore one ends up with a tall Leggy plant which has decreased fruit production and increased efficacy for disease. As we grow food, we promote the health of the plant for production. I am not saying that Aquaponics and Hydroponics does not do the same. We simply use a different, more natural means of support for our plants to maximize production. Only nature can grow perfectly all we can do is mimic her. Our job is to increase production, in less space, with the most efficient use of nutrients. We can incorporate our system directly into yours to boost production of food. It is not a competition between us. It is working together for a common goal. I have the upmost respect for Aquaponics and Hydroponics. Along with traditional farming techniques, Aquaculture, Hydroponics, and Aquaponics have been the cornerstone of food production over the past years. Thank you for the inquiry Steve. I hope I answered your question satisfactorily. Donald        

[Vlad Jovanovic]

Hi Donald...So you are saying that 'adding nutrients without the presence of soil' is what causes legginiess, and not the growers skill (as a hydroponicist...knowing what plant essential elements to add in what quantities and when, necessary type[s] of light, as well how much of said light, plant distancing/spacings, proper ventilation etc)?

I have had (and still have) many, many hydroponically grown, as well as aquaponically grown tomatoes, peppers, cucumbers etc...that tell a different story. Of course I purposely shoot for strong, stocky plants with short inter-nodal spacing that are highly productive (fruit full)  by anyone's standards.

As much as I love my outdoor organic garden (and Nature), there is absolutely nothing mystical or quasi-religious about what goes on in soil, and what functions it performs as a substrate for growing plants (this includes the complex and wonderful microbiology present within good soils, as well as the classic concerns of soil type, CEC, air to water ratio's, percolation etc)...not even in the "all natural" 40lb bags of Lowes top-soil 

There's certainly nothing wrong with trying to incorporate soil into an AP system if that is what one wishes to do...but to say that hydroponically, or aquaponically grown plants brought to fruition by a skilled and experienced grower are still going to be "leggy" and more difficult to "support", isn't really supported by reality.

I and others, have spent a number of decades growing in one type of soilless culture or another, and when done properly, have not experienced those problems that you mentioned.

Sounds like an interesting system btw...

 

Donald Holmes said:

Steve, You are speaking of flood and drain for the roots to breathe. I agree with you that in a rain forest there is faster growth than in a desert. There will be more nutrients in the rain forest due to more decomposition. So if one adds nutrients as in hydroponics and roots absorb those from the water then there would be a growth spurt of the plants. However there will also be an increase in the "leginess" of the plant secondary to support. That is why nature uses soil as a media (for support of the plant). The thinner the stem, the less nutrients which can travel its length for growth. Therefore one ends up with a tall Leggy plant which has decreased fruit production and increased efficacy for disease. As we grow food, we promote the health of the plant for production. I am not saying that Aquaponics and Hydroponics does not do the same. We simply use a different, more natural means of support for our plants to maximize production. Only nature can grow perfectly all we can do is mimic her. Our job is to increase production, in less space, with the most efficient use of nutrients. We can incorporate our system directly into yours to boost production of food. It is not a competition between us. It is working together for a common goal. I have the upmost respect for Aquaponics and Hydroponics. Along with traditional farming techniques, Aquaculture, Hydroponics, and Aquaponics have been the cornerstone of food production over the past years. Thank you for the inquiry Steve. I hope I answered your question satisfactorily. Donald   www.oldworldaquafarm.com      

[Donald Holmes]

Vlad, ...

 "to say that hydroponically, or aquaponically grown plants brought to fruition by a skilled and experienced grower are still going to be "leggy" and more difficult to "support", isn't really supported by reality.

I and others, have spent a number of decades growing in one type of soilless culture or another, and when done properly, have not experienced those problems that you mentioned."

The key phrase here is "a skilled and experienced grower." My goal here is not compare brain pans, nor to make someone else look bad so I can look good. It is simply a gesture of goodwill among experienced growers to pass on information which may help in-experienced growers to learn without going thru what you and I had too. I have studied traditional farming techniques and have applied that information to hydroponics and aquaponics. AquaFarming was created to enhance Aquaponics and Hydroponics. It was created to improve the growth rate and spacing issues of root vegetables. If there is no competition for nutrients plant spacing and growth rate are limited to root interaction. The density of of soil is greater than the density of clay balls, and it is considerably less expensive. As I understand legginess is a direct result of plant support. Increased density will help decrease legginess. I am saying let nature do the work. Donald