JohnMc

Sand Culture hydroponics, prep for IAVs

18 posts in this topic

Looking thru the old literature on hydro sand culture. Assumption being some research there might provide insight into the bed design for IAVs. Ran across this that might be of interest --

 

 

Pure sand can be used in trough or trench culture. However, in desert locations, it is often more convenient and less expensive to cover the greenhouse floor with polyethylene film and install a system of drainage pipes (PVC pipe 5 cm in diameter, cut one third through diagonally every 45 cm along the length of the pipe, with the cuts facing downward) and then to backfill the area with sand to a depth of approximately 30 cm. If the depth of the sand bed is shallower, moisture conditions may not be uniform and plant roots may grow into the drainpipes. The area to be used as planting beds may be level or slightly sloped. Supply manifolds for nutrient solution must be sited accordingly.

 

Various kinds of desert and coastal sand with different physical and chemical properties have been used successfully by the University of Arizona workers. The size distribution of sand particles is not critical, except that exceptionally fine material such as mortar sand does not drain well and should be avoided. If calcareous sand is used, it is important to maintain a nutrient solution with a neutral pH, and increased amounts of chelated iron must be applied to the plants. Sand growing beds should be fumigated annually to prevent the introduction of soilborne diseases and nematodes.

Irrigation practices are particularly critical during the high-radiation summer months, when crops may have to be irrigated as many as eight times per day. Proper irrigation is indicated by a small but continuous drainage, 4-7% of the application, from the entire growing area. Evaporation of water around small summer tomato transplants is often high, which can lead to a slight buildup of fertilizers in the planting bed. Extra nitrogen causes excessive vegetative growth, and reduces the number of fruits. This can be avoided by reducing the amount of nitrogen in the solution from the time of transplanting until the appearance of the first blossoms. Drainage from the beds should be tested frequently, and the beds leached when drainage salts exceed 3000 ppm.

 

The principal crops grown in sand culture systems are tomato and cucumber, and yields of both crops can be high. Seedless cucumber production has exceeded 700 mt/ha.

 

http://www.agnet.org/library.php?func=view&id=20110729175702

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Hi John,

 

The difference between hydro sand culture, and iAVs, is the soil microbiology that is unique to iAVs.......and it's a huge difference.  A number of the conditions (that your quote alludes to) simply do not apply to iAVs.

 

One of the things that becomes apparent when one begins to look at the use of sand in food production is that its use is far more widespread than most people are aware.  While its use has been eclipsed by rockwool and other media in commercial greenhouse operations, much of the so-called soil-based vegetable production still happens in "fertigated" sand.....in places like Almeria (Spain), Arizona and Mexico.

 

Gary

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Hi John,

 

The difference between hydro sand culture, and iAVs, is the soil microbiology that is unique to iAVs.......and it's a huge difference.  A number of the conditions (that your quote alludes to) simply do not apply to iAVs.

 

One of the things that becomes apparent when one begins to look at the use of sand in food production is that its use is far more widespread than most people are aware.  While its use has been eclipsed by rockwool and other media in commercial greenhouse operations, much of the so-called soil-based vegetable production still happens in "fertigated" sand.....in places like Almeria (Spain), Arizona and Mexico.

 

Gary

No quibble on the differences Gary. I am looking at some of the old references in regards to the hydrostatic/dynamic aspects of the sand.

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No quibble on the differences Gary. I am looking at some of the old references in regards to the hydrostatic/dynamic aspects of the sand.

 

I think that's a good idea, John.....you never know what's buried in old documents.   I know that, prior to knowing Mark, I read Steve Diver's description of Mark's work (and the subsequent glowing assessment of the Speraneo system) on several occasions.....and I had a very different impression of what iAVs was from what it turned out to be. 

 

It was only after working with Mark that I understood the full implications of Speraneo's actions in substituting gravel for sand - and the way iAVs' destiny was impacted.

 

All which suggests that taking a close look at the old stuff often yields details and insights of immeasurable worth......not to mention re-invented wheels by the dozen.

 

Gary

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Have a look at this document from the 70s which also explains quite a lot.  

http://vric.ucdavis.edu/pdf/hydroponics_soillesscultureofgreenhouse%20vegetables.pdf

 

I am particularly interested in looking at the full floor sand culture system design and would like to adapt it in a new project. Cut/paste - "Full-floor sand culture has been successful for vegetable culture in greenhouses and is considered a good means of providing plants with a uniform, well-drained rooting medium (fig. 3)."  

 

There are several other good things for Aquaponics-iAVs enthusiasts/soil-less culturists  in this paper.

 

"Comment is free… but facts are sacred."  - CP Scott, 1921 Guardian editor -

Edited by vkn (see edit history)
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Have a look at this document from the 70s which also explains quite a lot.  

http://vric.ucdavis.edu/pdf/hydroponics_soillesscultureofgreenhouse%20vegetables.pdf

 

I am particularly interested in looking at the full floor sand culture system design and would like to adapt it in a new project. Cut/paste - "Full-floor sand culture has been successful for vegetable culture in greenhouses and is considered a good means of providing plants with a uniform, well-drained rooting medium (fig. 3)."  

 

There are several other good things for Aquaponics-iAVs enthusiasts/soil-less culturists  in this paper.

 

"Comment is free… but facts are sacred."  - CP Scott, 1921 Guardian editor -

Did you read the NPK values at the end

Formula 1, 105-33-138

              2, 106-62-156

              3, 112-41-300

              4, 236-60-300

And fish poo is 5-3-2

Does anyone else see a problem here?

Needs to be bumped a bit to compete.

 

Are the 4 formulas real world and we are running poor/fools world.  No wonder my plants are not growing well in fish poo.  That list has a complete chemical list and the amounts used.  No secrets. It is a great start to understanding the real world.

 

When I read things like this it leads me to wonder what is the truth.  Is Most AP just a gimmick or is it better then what formulas they made and sold.

 

Do I have reason to ask?  Thank you for the link, it is an eye opener.  I wonder how real fertile ground would measure up. That's my next look up. 

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Did you read the NPK values at the end

Formula 1, 105-33-138

              2, 106-62-156

              3, 112-41-300

              4, 236-60-300

And fish poo is 5-3-2

Does anyone else see a problem here?

Needs to be bumped a bit to compete.

 

Are the 4 formulas real world and we are running poor/fools world.  No wonder my plants are not growing well in fish poo.  That list has a complete chemical list and the amounts used.  No secrets. It is a great start to understanding the real world.

 

When I read things like this it leads me to wonder what is the truth.  Is Most AP just a gimmick or is it better then what formulas they made and sold.

 

Do I have reason to ask?  Thank you for the link, it is an eye opener.  I wonder how real fertile ground would measure up. That's my next look up. 

The formula mentioned in the pdf is talking about g/100 gallons of water.  I wonder what did you mean by 5-3-2?

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5-3-2 is the published NPK value for fish waste.

All NPK values are supposed to be in percentage of the whole.

Why would anyone mix grams and gallons.  Should be grams and liters.

 

The numbers I pulled out are their ppm numbers.

1 mg = 1 ppm in a liter.  After midnight now and the eyes are giving up.

ppm does not refer to any gallon or liter it is a ratio and all of the numbers they have are much higher then any fish waste.

 

How would you explain this? I'll be back tomorrow.

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Lets see if I get this right.  If we use the percentages of 5-3-2 then if the water in a liter, 1 million mg would have an NPK value of N, 50,000 P, 30,000 and K of 20,000 ppm.  The water would be mud at that point. So dilution comes into the calculation. At least a factor of 1,000. To get 50,30,20.

 

500 would be closer @100-60-40.  So it seems that no matter what the K value will be a lot lower then the designed numbers by hundreds of ppm. What would you say about the K factor? Don't need it, Need to bump it or add something with good K values.  So if the concentration of fish poo is correct and it contains the 5-3-2 then K should be the first work around. 

 

Figuring the actual load of NPK coming out of the fish would be another act.  I have no NPK test kits here.  Many things are made here and not sold here due to the companies license and taking the risk that locals would buy it.  Without a demand that will never be worth the money it takes to get a local sales license.  It make business more then twice as hard in accounting so no one wants to do it.  It is cheaper to ship it out and then back in and sell it on the black market.  So just because you all buy things from here does not mean we can. 

 

Please advise as to what your opinion on this is and if you bump any of the values. At some point the micros need a look at also.  they should be just as important. I doubt if all fish excrete exactly the same NPK numbers and most of you use tilapia. A fish I don't like to eat. So this key has to be fish, food and temp if doing a measurement on just the fish.  Is the water at least at that 500 dilution point?  Then will the load of what ever one uses, sand or clay, will it take it out and use it well. I hope these are easy everyday questions you do all the time. It seems I need 30 times more K.  what do you think?

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It looks like by letting the waste dry out on the surface allows it to be in its closest form to the 5-3-2 or 50,000, 30,000 and 20,000 then it will leach at those numbers and not the diluted ones.  Is that fair to conclude? If so, can one set up just a sand bed to collect them for other plants that are not on any loop , like a tree in the yard.  Simply adding this fert to the top of the soil should have the same effect. In that case any pond can be pumped over a sand base to have the NPK taken out and used on crops. Every fish farm here would be a gold mine of ferts?

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5-3-2 is the published NPK value for fish waste.

All NPK values are supposed to be in percentage of the whole.

Why would anyone mix grams and gallons.  Should be grams and liters.

 

The numbers I pulled out are their ppm numbers.

1 mg = 1 ppm in a liter.  After midnight now and the eyes are giving up.

ppm does not refer to any gallon or liter it is a ratio and all of the numbers they have are much higher then any fish waste.

 

How would you explain this? I'll be back tomorrow.

I am not a scientist nor an engineer and never tried or got an opportunity to go into fish waste/nutrient details so deep.  I like the way you try for finite details.

 

Why would anyone want to mix grams and gallons?  For your question, this is what I found from engineering tool kit.  Several notations are in use.

1 ppm

    = 2.72 pounds per acre-foot

    = 1,233 grams per acre-foot

    = 1.233 kilograms per acre-foot

    = 0.0283 grams per cubic foot

    = 0.0000624 pounds per cubic foot

    = 0.0038 grams per US gallon

    = 0.058419 grains per US gallon

    = 0.07016 grains per Imperial gallon

    = 1 milligram per liter (mg/L)

    = 1 microlitre ( μL ) per liter

    = 0.001 gram per litre

    = 8.345 pounds per million gallons of water

 

I think what UC Davis mentioned is the ppm derived from those various hydroponics nutrient solutions in grams per US gallon and not the percentages of elemental composition.  I could be wrong.

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So you see the 1 mg per liter is by far the easy one. To measure 0.0038 grams is not an easy thing to do an I have a nice gram scale but it does not go that low. Even 1 mg is hard, it is almost a flake of dust.

 

Do you have any NPK numbers for your work with iavs?  Do you need to bring anything up or does the dried waste give well more then the water would ever give as I expect it will.

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So you see the 1 mg per liter is by far the easy one. To measure 0.0038 grams is not an easy thing to do an I have a nice gram scale but it does not go that low. Even 1 mg is hard, it is almost a flake of dust.

 

Do you have any NPK numbers for your work with iavs?  Do you need to bring anything up or does the dried waste give well more then the water would ever give as I expect it will.

Honestly never thought of looking at what those numbers are. I now think I should check those when I get the next opportunity. Never felt the need to send the produce/leaves of plants for tissue analysis or the water for elemental composition studies either.  Plants get everything they need from the quality fish feed used and adequate feeding regimen.  The dried waste on top of the furrows, I see them vanishing periodically.  Whenever there is enough foliage what you will see is a clear surface.    

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I remembered yesterday that many, many moons ago in school we learned how the cowboys who pioneered the wild west drank water.  They had a wooden chute in which they added local gravel and sand.  By pouring the water in the gravel end it would travel thru the sand end and come out drinkable.  Now they probably got this idea from the local Indians, who got it from ? and so on. So that dates back over a hundred years now.  So believing the sand cleans the water is very easy. It is one of natures best filters.  Do you know how they take slugs of soil out to get them tested?  Maybe 10 or so and then mixed together. That should show how much fert is in the captured area.  To learn it goes away from time to time is new to me.   I don't think I have read that before. The surface microbes must have a feeding frenzy at times. 

 

So working with a more pure fish waste then in AP, the plants must get very high doses of NPK.  If that happens will the N number actually be too high for kids to eat? If indeed it will leach into the roots at a high number like 50,000, how much of that will get into the plant for us to eat. Since the sand should hold almost everything, I would think that the bio load would increase daily and only removed by the plants.  It should pull al of the NPK out of the tank and suspend it in the grow tanks.  It almost seems that once it is started, one could take it off line and it should do well for months on just plain water.  Does that make sense?

 

Outside of the box again:  If you took a sheet of plywood on an angle and just laid in 1/2 inch of sand over the top and pumped it all day with Fish waste. It should settle out on the top the same way and drain clear water back to the FT or pond.  After some amount of time, shut it off and let it dry and then sell it or use it on crop fields. A floating sheet can be put into a pond, like our huge fish ponds and do 3 things, Clean the water, pull out all of the solids and make a cash flow from the waste. What mix to start with would be a question because all of it will be mixed into a bag for sale later. A farmer might even give you some of his dirt so you could mix it for him.  If it works, it could take out a lot of chemical ferts they now need and use.  Currently all fish farms just dump all of the waste water out of the ponds every year and bulldoze out the bottoms and bury that mass.  Once they get to a deep depth, the last time it is scraped, some of them will line the pond.  It is a huge investment for them to line a monster pond.  If we were able to pull these solids out they would never need to drain and clean the ponds. We would get free ferts or cheaper high quality ones.  Has to be better then chemicals.

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Interesting you say that about the bed storing nutrients.   My sand bed is currently decommissioned. while I plan and build an upgraded system.   It is currently growing tomatoes with nothing more than rain.  I've not pumped it in months or added any fertilizer. Heck, I didn't even plant the tomatoes, they just sprung up.

 

One issue with your NPK formula is a lot of the nutrients will be stored in microbial growth and  may not all be water soluble.

 

As for you floating sand bed....http://circkles.com/blogging/gardening/2014/07/19/eco-garden-design-chinampas/

Edited by Ravnis (see edit history)

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Well I also have a small gravel bed that has not been given any new nuets in 3 months. Off Line.  It started to do better went it went off line.  So yea the finite  sand or gravel once it is loaded will hold plant food for months.   I did the same test with clay balls and it all died within a week.  The water and nutrients pass thru clay balls at a very high speed. This is one reason they have to be run all the time. No water no food. 

 

If some items are not water soluble then either will not be used by the plants and flushed on the next bed cleaning.  Rather the root can use them or not I am not sure because I don't know which ones you mentioned.

 

The link might be done wrong. It is driving me back to the top of this thread and not out....Your  a Mod, can you fix it?  I am interested in a floating sand bed for fish farms.  I have a buddy real near me that has a fishing pond for profit. Same principle.  He also has a very large garden.  So I have some meetings to set up over beers at night.

 

I do believe that the ball beds are the most pervious.  And this is a reason why the new beds don't work well.  They all tell me the beds need 6 months to a year before they preform well.  It is a reason some of them need worms.  By that time the beds are loaded with the poo.  Sand should load pretty fast by comparison.  A week to 3 and it should be on its way.  I think this is the reason my new test beds are way under producing dirt.  Dirt is ready to go now.  Clay takes a year. Most AP sites are run by people that sell the stuff and have beds that have been running for years.  They show us large crops and say, "This is what you will get"  Ok if you wait a year and run a million problem in that time.  When I went to just old plain fish gravel, they out produced my clay balls all the time.  They hold the poo in place and release it right from day one.  With the clay it goes straight thru for months and months.

 

And I still don't know why people want to add fish to DWC.  To get good nutrition to the roots from fish poo is not easy with just water.  Second there seems like there is just the roots for a filter. So if you pull out the plant on harvest day you are looking at a cascade of problems instantly.  The only way around that is never ending staggered planting.  Fish also.  The big guys must go crazy trying to always balance everything.

Edited by Deuem (see edit history)

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LInk should work now. 

 

I once had the idea to just bottle the water and sell it as liquid fertilizer.  When I tried it on potted plants, I did not get the same results as plants in the growbed.  I'm no horticulturist by any means, but to me there was something more to the growth than just what was in the water.  Other members have cited Dr. Ingraham and her work in microbial interaction.  A pdf on the subject I am currently perusing http://aglifesciences.tamu.edu/rootbiome/wp-content/uploads/sites/38/2015/06/2014-Huang-et-al-review-cjb-2013-0225.pdf

Much of it is over my head, but I've had enough microbiology to understand some of it.

 

   I am not impressed with clay balls either and ever increasing media size  and thus decreasing surface area appears to be detrimental to the process.  There was a time when AP hobbyist attempted to ever increase the media to  improve drainage times.  After giving sand a go, I'm convinced this was in error.  I believe the original usage of clay balls was to hold root and plant support in DWC, where the nutrients were in solution and needed to easily get to the plant roots.  To me they are insanely expensive and poor performers in ap growbeds.     

 

Being in china, I would think you would be in one of the birthplaces of integrated farming. I recall references to fish growing in rice paddies during the flood stage.

 

Bioremediation of the farm waste you described is likely a huge economic opportunity.  I know in the states , a few pig farms have used duckweed to capture waste out of lagoons of pig dung and that has been successful. The duckweed can be used as poultry feed or green manure.    Through history fortunes have been made turning a waste product into a commodity.  Good luck with your fortune.

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Hello Ravnis: Both links are working now and the aglifescience is glazing over my eyes with data.  That one is a print and read doc.

 

I have not seen any of the rice paddies used for fish yet, Grass Eels, Yes. I guess it is too much work now a days.  They all buy babies from an area breeding factory and put them right into a new pond. The entire pond is harvested around the same time and off to the next pond.

 

If I use the water from the AP for other plants right away, it seems to help a lot.  If I store it, the bacteria in the jug goes crazy and the liquid becomes deadly for the plants.  Mine turns a bright red. I do this 2 ways, just pull off 5 liters at a time and pour it on the house plants or when I change the filter floss I place it in the 5 liter bucket, add 4-1/2 liters of fish water and stir it up until the floss is a bit clean.  This is the stuff that will turn red after a week if not used.

 

At some point in time I will ask my friend with the fish pond/ gardens if he wants to try it.  He uses the fish water now for the garden.  Keeping things pathogen free would be a question. We could always bake the sand first to kill off any live bugs.

 

At this time I am most interested in waiting for the OP to do a study of the amount of N in the plants and if it is at a healthy level for kids to eat the plants.  With the sand, the amount of N should be very high and I am not sure if it is overloading the plants or if they just take what they need and that's all. In other words, is iAVs too good?  Also a good soil sample will tell what's going on up top. The numbers should be very high, IMO.

 

It sounds like VKN understands my question and has the tools to figure it out.  It might be as simple as turning it off for a month and switch to water only to dilute all numbers,  Purge the plants or everything I am thinking about is bogus. IMO it must be in the middle somewhere.

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