Jump to content
GaryD

Integrated Aqua/Vegeculture System (iAVS)

Recommended Posts

 

Question is...

 

Does the algae return the same amount of nutrients it absorbs after its decomposition? Or... Is there nutrient loss due to mere action of algae simply growing to survive?

 

On my return to UAE last April, the system had been poorly managed for 3 weeks.  The EC was above what I could read at 6.5... nothing of use will grow in that.  The solution to nutrient reduction and reuse was to lift all of the rafts off 3600m2 and expose it to sunlight.  Within 24 hours algae started and within 3 days the raft was covered in the thick blanket.  See image below.

 

Following that and the reduction of the EC, we recycled the algae through the trickle filter to capture and reuse it.  However, the algae plays no significant role in the nutrient cycling on the farm.  It was convenient to use the algae to capture the nutrient, then kill the algae and capture that for mineralization compared to dumping 1,000,000 liters of water and exchanging it.

 

You guys are still over thinking the processes.  Operationally at a large scale, sand would provide more headaches than benefits by the evidence provided so far.... and it would not have prevented this issue, nor would it have helped solve it.

Share this post


Link to post
Share on other sites

Hi Gary,

 

Could I please ask that when you quote some one, to leave their name in the quote... Im often finding myself reading back pages to confirm who said what.

 

Cheers

Joe

Share this post


Link to post
Share on other sites
Gary - have you considered the expense and problem having to replace sand will incur? When the sand needs to be cleaned or sterilized - where will you do it? How long will the bed be out of operation? And what kind of heavy machinery will be required to do it?

 

We don't know, at this stage, that it will need to be replaced.  In any case, at the small to medium commercial greenhouse operation, it would be a job for skid steer loaders.

 

Sterilisation is easier than replacement.  The growing medium is covered in plastic and a fumigant is applied.  As I said earlier, it's already standard practice in many tomato greenhouses that use soil as a medium…..also in field vegetable crops.

 

The bed is out of operation for two to three weeks from recollection…..and that's where the fumigation is used for weed control.  These days, it may be even easier than I recall……and that assumes that it's required at all.  Crop rotation may eliminate the need for fumigation.

 

At the end of the day, the yields may actually support some of these theoretical costs.

 

Since fish food doesn't contain enough potassium, iron, or boron for plants...... either the sand bed was contributing something, OR mineral rich water was used in the system.  There's also the possibility that the plants were deficient in potassium and iron.

 

You could be right…..but that only supports more serious study of the medium to see what its capabilities are for as much as we don't already know.  Incidentally, Mark undertook laboratory tissue analysis to determine where all of the nutrients came from and where they went.  The results of that were

 

By the way, you haven't yet provided details of the "criminal" way in which his fish were handled.

 

Operationally at a large scale, sand would provide more headaches than benefits by the evidence provided so far....

 

Long term, that may be the case…..but, at this stage, the evidence (that we've seen thus far) actually supports the use of sand culture.

 

 

Gary

Share this post


Link to post
Share on other sites

Hi Joe,

 

 

Hi Gary,

 

Could I please ask that when you quote some one, to leave their name in the quote... Im often finding myself reading back pages to confirm who said what.

 

Cheers

Joe

 

Hi Joe,

 

Believe it or not…..I only just twigged to the quote/multi-quote feature.  Whenever I've quoted things in the past, I've always used the speech bubble thing in the post editor.  Your suggestion makes sense.  I've just got to remember to use the proper editing option in future.

 

Gary

Share this post


Link to post
Share on other sites

Long term, that may be the case…..but, at this stage, the evidence (that we've seen thus far) actually supports the use of sand culture.

 

 

Gary

 

Plenty of evidence sterilization needs to be undertaken between each crop.  While sterilizing or managing a 10m2 garden will be easy at acre and above size, it wont be.  There is special consideration to food pathogen not only plant and fish pathogen harbored by the media which is also the case for gravel and the other medias that can not be easily replaced.

 

While I am neither way, I only caution its use at a large scale because there is no evidence that supports its use in a biological system.  However, I can see this conversation is becoming circular which is common place where inexperience dominates the discussion.

Share this post


Link to post
Share on other sites

Plenty of evidence sterilization needs to be undertaken between each crop.  While sterilizing or managing a 10m2 garden will be easy at acre and above size, it wont be.  There is special consideration to food pathogen not only plant and fish pathogen harbored by the media which is also the case for gravel and the other medias that can not be easily replaced.

 

While I am neither way, I only caution its use at a large scale because there is no evidence that supports its use in a biological system.  However, I can see this conversation is becoming circular which is common place where inexperience dominates the discussion.

 

Fumigation of soil is practised on a broad acre basis as well as in greenhouses.  Your position has softened from the original "multitude" of studies (and that's a responsible thing given your failure to provide evidence of the studies to which you referred).  I take your point about caution - one should never bet more than one is able to lose.

 

Just to be sure, when you refer to "inexperience" you are talking about both of us, aren't you?

 

Gary

Share this post


Link to post
Share on other sites

Fumigation of soil is practised on a broad acre basis as well as in greenhouses.  Your position has softened from the original "multitude" of studies (and that's a responsible thing given your failure to provide evidence of the studies to which you referred).  I take your point about caution - one should never bet more than one is able to lose.

 

Just to be sure, when you refer to "inexperience" you are talking about both of us, aren't you?

 

Gary

 

While fumigation is practiced in soil applications, the benefits of applying it to a biological system, as I previously stated (sterilization may not be a suitable option for a system that relies on bacterial activity), has no supporting evidence it would be effective or that it would not destroy the ecology the system depends on.

 

When I talk about inexperience, again there is no evidence of people in this discussion with experience in the use of sand in a commercial context and even less with experience in commercial aquaponics.  So, with limited factual information available, the discussion diminishes to circular conjecture.  For example, in the last three posts I have the same thing in three different ways to no benefit to the discussion.

 

With that I leave you to your ideas.

Edited by Paul Van der Werf (see edit history)

Share this post


Link to post
Share on other sites

Definitely correct about lack of experience in commercial application, at least on my part.   The pathogen issue aside,  after watching your videos where they were harvesting by pushing  the rafts forward in the tank itself, it seems harvesting logistics would be significantly  more difficult with the sand system or a loss of growing space due to more walkways being required.

 

I do wonder if it would be possible if it proved worthwhile as a growing system to build beds in such a way as machinery could harvest from them. 

 

Also wonder if it would be possible to apply principals of soil management such as Dr. Ingraham  is promoting  to manage pathogen problems instead of sterilization.  Of course, these solutions would have to be practical and any costs of implementation would have to be low enough that there was significant benefit over NFT,  raft, or plain hydroponic culture.

Edited by Ravnis (see edit history)

Share this post


Link to post
Share on other sites

Sterilisation is easier than replacement.  The growing medium is covered in plastic and a fumigant is applied.  As I said earlier, it's already standard practice in many tomato greenhouses that use soil as a medium…..also in field vegetable crops.

 

A fumigant? Yikes. That's not sustainable, it's not healthy for the environment, and it's downright dangerous for the workers. Here in California, soil fumigants are on their way out the door, even for crops like strawberries.

Share this post


Link to post
Share on other sites

I do wonder if it would be possible if it proved worthwhile as a growing system to build beds in such a way as machinery could harvest from them. 

 

 

I don't think machinery is advanced enough yet. I think manual harvest is still the best.

 

 

If you want machinery to harvest crops, then this is reverting back to poor quality food from many soft food crops (which is most vegetables/fruit) that can be easily bruised thus result to quicker spoilage. This is the main reason, not the lack of organics nor gmos, why many "industrialized" crops have the nutrient density that they have, that is harvesting the crop way too early either due to machinery or weather creating plant stress that change the plant's nutrient density.

 

 

Machinery and impending weather is very rough on crops.

 

Also, the machinery cannot make judgement calls like human picking crews can since all fruit or vegetables on the vines do not ripen at the same pace.

 

 

Tomatoes for example. Broad acre tomatoe fields involving machines are harvested when the tomatoes are incredibly green (then artificially ripened leading to tasteless red tomatos to have a brix value of around 3 instead of 10). Machine harvesting during ripened crops leads to bruising of the fruit, thus resulting in quicker spoilage. So, there are roguing crews (i.e., manual labor pickers) that go out to first harvest the very ripe tomatoes and these ripe tomatoes are given a premium price by the market due to their extra quality, but this is a very small percent of the total field's yield

 

My dad and I used to grow organic white food corn, but, when the crop would experience too much stress such as machinary too rough creating fractured kernels or a drought or hailstorm leading to plant stress changing the nutrient density, then the processors buying this corn would outright reject entire fields due to only testing one truck load. This is the major reason why we stopped growing organic white food corn.

 

There's a fella here that grows organic sweet corn on around 200 acres, but he will only using big machinery if there is an impending hailstorm during harvest. Otherwise, the crop is picked by roguing crews.
Edited by crsublette (see edit history)

Share this post


Link to post
Share on other sites

Hi Paul,

 

When I talk about inexperience, again there is no evidence of people in this discussion with experience in the use of sand in a commercial context and even less with experience in commercial aquaponics.  So, with limited factual information available, the discussion diminishes to circular conjecture.  

 

You have no more experience with sand culture than anybody else here......and your experience with commercial aquaculture is not relevant to this situation. 

 

For example, in the last three posts I have the same thing in three different ways to no benefit to the discussion.

 

You said that sand had been trialled "a multitude of times" but the only examples that you provided were Mark's trials.  While you kept saying that people should exercise caution (a general principle with which I agreed) you failed to make a cogent case against sand.  The fact is that there's more evidence to support the use of sand than there is to not use it......notwithstanding your claims to the contrary.

 

With that I leave you to your ideas.

 

Good.  Perhaps Ravnis can have his thread back.  

 

Definitely correct about lack of experience in commercial application, at least on my part.   The pathogen issue aside,  after watching your videos where they were harvesting by pushing  the rafts forward in the tank itself, it seems harvesting logistics would be significantly  more difficult with the sand system or a loss of growing space due to more walkways being required.

 

Sand is better suited to vine crops like beans, tomatoes, peppers and cucumbers.  They are usually (and best) harvested in greenhouses by hand.  Even where such crops could be grown on rafts, it would not be practical to push the rafts along as is done in the UAE project.

 

I do wonder if it would be possible if it proved worthwhile as a growing system to build beds in such a way as machinery could harvest from them. 

 

Machinery could be used to remove crop residues to form the furrows and to plant out new crops......and, if was deemed to be necessary after several years, to swap the sand out.

 

Also wonder if it would be possible to apply principals of soil management such as Dr. Ingraham  is promoting  to manage pathogen problems instead of sterilization.  Of course, these solutions would have to be practical and any costs of implementation would have to be low enough that there was significant benefit over NFT,  raft, or plain hydroponic culture.

 

That's an interesting idea.  If you consider that soil without the microbes is just "dirt" (as Dr Ingham puts it).....a mix of sand and clay......then there would be little difference for practical purposes from sand.  Sand may prove to be similar to soil when it comes to supporting microbial life that retards harmful viruses, nematodes, etc.

 

Gary

Share this post


Link to post
Share on other sites

I really don't mind at all.  I love the viewpoints expressed by all and am thankful for insights from others.  I feel an informed person has the ability to judge whether information is relevant or not. 

 

My knowledge of sand beds is in it's infancy and while trying to find other sources to compare, I came across a post from a fellow that invested $500,000 in aquaponics and lost it all. He did not specify any details, so no knowledge whether it was raft or a copy of the Speraneo method.  I think Paul is very valid to play devils advocate before someone looses his life savings going off half cocked and half informed.  It is not the first time I have seen something look good at first inspection, but turned out to be not that good with more detailed examination.

 

I was all but ready to abandon media all together before Mark showed up due to constant issues with deficiency of minerals. That went away with the sand and leaves me with two options that I currently considering. 

1  that something about the sand bed configuration increased the nutrients reclaimed. 

2  sand had stored nutrients in it.

 

 

I wish to believe the former,  but can't get away from the feeling it's number 2.  Without empirical evidence, I can do little more than guess at this time.

Share this post


Link to post
Share on other sites

I agree with everything that's been said about exercising caution…..but that applies to every aspect of investment in general and farming investment in particular.

 

I also agree (as does Mark) that there's still much to be learned about sand culture.

 

I'd like to believe that your observation about soil microbes is on the mark.  I guess we'll only know, one way or the other, through further investigation.

 

By way of a general observation, greenhouse culture has a raft ('scuse the pun) of known issues……everything from mineral deficiencies, logistical issues, insect problems, compliance problems, etc…..that have to be considered before setting up.  I don't see sand as being any different.

 

I don't even see the replacement of the sand (to a point outside of the greenhouse) where it could be reconditioned, as being insurmountable…..using the same infrastructure/ equipment as is used for harvesting. 

 

I lived in the Virginia district of South Australia……a major Australian centre for tomatoes.  All of the tomatoes in the area were grown in soil inside glasshouses.  They had to deal with all of the issues that I listed and more.  That suggests to me that iAVs might (particularly given its productivity relative to other growing methods) be viable.

 

Anyway, it's all been said…..so now we just need to confirm our beliefs/suspicions.  My main point, I guess, is that there appears to be enough positives around sand to make it worthy of further investigation.

 

Gary

Share this post


Link to post
Share on other sites
My knowledge of sand beds is in it's infancy and while trying to find other sources to compare, I came across a post from a fellow that invested $500,000 in aquaponics and lost it all. He did not specify any details, so no knowledge whether it was raft or a copy of the Speraneo method.  I think Paul is very valid to play devils advocate before someone looses his life savings going off half cocked and half informed.  It is not the first time I have seen something look good at first inspection, but turned out to be not that good with more detailed examination.
 
 
Yep, there is definitely no end of risk takers to jump on the band wagon that go to try out the purveyor's methodologies due to the purveyor showing great results in their trials.
 
 

 

I was all but ready to abandon media all together before Mark showed up due to constant issues with deficiency of minerals. That went away with the sand and leaves me with two options that I currently considering. 

1  that something about the sand bed configuration increased the nutrients reclaimed. 

2  sand had stored nutrients in it.

 

 

Your deficiency issues would have been fixed as well with a properly built soil wicking bed as well, as has been shown by Mr. Van der Werf with his many many trials with the Earthan Beds.

 

I think the best comparison would be to look at the soil biological hydroponic operations and wonder why they did not choose to use primarily sand. I imagine there are also these biological hydroponic operations on the receiving backend of aquaculture facilties. Mr. Van der Werf has definitely proven soil wicking beds impact through his extensive work with with his Earthan Beds.

 

 

 

So.... For the past 20+ years, then....

 
1. Has  been ignorance, lack of confidence, lack of courage, or "peer pressure of integrated aquaculture agribiz" that professionals have chosen DWC/NFT and not adopted the iAVS method "whole hog"??
 
Or
 
2. Could there be sincere factual reasons and unanswered concerns why the iAVS system is not adopted "whole hog"?

 

 

 

Due to Mr. Van der Werf's accounting of his observations of other's commercial experiences utilizing primarily sand within hydroponics and the reasons he has given that indicates the iAVS needs more long-term trials, then I suspect #2 is the more logical question that should be asked.

Edited by crsublette (see edit history)

Share this post


Link to post
Share on other sites

Anyway, it's all been said…..so now we just need to confirm our beliefs/suspicions.  My main point, I guess, is that there appears to be enough positives around sand to make it worthy of further investigation.

 

 

What about the horrible food conversion ratios seen in McMurtry's trials? 

Share this post


Link to post
Share on other sites

Hi s

What about the horrible food conversion ratios seen in McMurtry's trials? 

I don't think they where horrible ? compared with other AQ operators of the time ?

Or are you comparing with the FCR's of today ?

Anyhow what does that have to do with sand-bed's as a choise of growing media ?

 

cheers

Share this post


Link to post
Share on other sites

I believe gary mentioned McMurtry's FCR (Food Conversion Ratio) peaking at 2.6.  I call that horrible. The research i've seen talks about FCR's closer to 1 for Tilapia fed a diet similar to McMurtry.  

 

I think McMurtry's high FCR was a result of relying solely on the sand beds for filtration and partially for aeration. Which would work if you had 12+ beds such that one bed was always draining, but on the non-commercial scale 12+ beds is tough sell.

 

If you have one bed, running on a 4hr cycle (8x a day), then there's a significant period of time where the water in the fish tank is not being treated and waste products are accumulating in the fish tank while oxygen decreases. Tilapia can survive almost anything, but poor water quality will increase their FCR, impacting your bottom line. 

 

Running some sort of aerated biological filter on a constant basis would likely decrease FCR and increase stability of the important aquatic life parameters.

 

Just my idea as to how sand-bed based systems might be improved.

 

Any thoughts?

Share this post


Link to post
Share on other sites

In his first trial he did not have air, but recall that he added air to the system in future trials to eliminate low O2 levels.   Low O2 levels can be a contributing factor.  I myself have witnessed poor growth with tilapia when kept in a small space and there is a relationship to volume space and growth rate subject to diminishing returns.

 

Catfish food was likely a different composition as to what it is today.  I had paid a premium price for 45% tilapia feed when I first started, but through trial and error , found I have the same growth with 32% catfish food at the hobby level. At commercial levels it might be worth the extra, or for fingerlings that require a different diet the first 60-90 days.

Share this post


Link to post
Share on other sites

Hi Scott,

 

I believe gary mentioned McMurtry's FCR (Food Conversion Ratio) peaking at 2.6.  I call that horrible. The research i've seen talks about FCR's closer to 1 for Tilapia fed a diet similar to McMurtry.

 

No, I dd not mention FCR at all.  When I looked at the spreadsheet that contains all of his performance data it talks about a median FCR of 1:1.5….which is what I'd expect.

 

I think McMurtry's high FCR was a result of relying solely on the sand beds for filtration and partially for aeration. Which would work if you had 12+ beds such that one bed was always draining, but on the non-commercial scale 12+ beds is tough sell.

 

By all published accounts, the filtration was effective, aeration was good and the FCR was adequate.  Mark also reports that he never had a fish die that he didn't intend to kill.

 

Running some sort of aerated biological filter on a constant basis would likely decrease FCR and increase stability of the important aquatic life parameters.

 

Since your proposition is premised on the wrong numbers, you may be attempting to deal with a problem that doesn't exist.

 

Just my idea as to how sand-bed based systems might be improved.

 

​I'm sure it can be improved.   As Mark has stated, on several occasions, he never set out to optimise anything.  He sought to establish that sand culture worked - and he did that to the extent that his research evidenced.

 

Any thoughts?

 

Just this one.  You've stated that the way that he kept his fish was criminal……with no corroborating evidence…..and, more recently, you've said that I spoke about an FCR of 2.6.  I never posted anything about his FCR ('til this post) and it seems that, wherever you got the number, it was inaccurate anyway.  We have yet to see evidence of a problem in either situation.

 

 

Gary

Edited by GaryD (see edit history)

Share this post


Link to post
Share on other sites

In his first trial he did not have air, but recall that he added air to the system in future trials to eliminate low O2 levels. Low O2 levels can be a contributing factor. I myself have witnessed poor growth with tilapia when kept in a small space and there is a relationship to volume space and growth rate subject to diminishing returns.

Catfish food was likely a different composition as to what it is today. I had paid a premium price for 45% tilapia feed when I first started, but through trial and error , found I have the same growth with 32% catfish food at the hobby level. At commercial levels it might be worth the extra, or for fingerlings that require a different diet the first 60-90 days.

What's the exact food you are using?

Thanks

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.

×
×
  • Create New...