Hypothesis: I want to see if it is possible to grow hydroponically with bioslurry without mitigating the slurry prior to starting the grow cycle.
Biopoincs and dialing in how to use bioslurry for growing hydroponically without soil is a fantastic opportunity to create a system of growing food that is completely plate, to digester, to garden, to gas stove, then back to plate again. Think of the hanging towers of Babylon as the first use of hydroponics, they figured out how to feed their plants without patented factory made nutrients eons ago, so can we. There are several easy DIY methods to grow hydroponically that can be done for under $100 and some for under $50 using materials that can be purchased mostly from a hardware store. The easiest to make and maintain are drip irrigation with coco logs and deep water. Nutrient film technique (NFT) and aeropoincs are much less forgiving (i.e., the plants will die if they don't have water spraying or dripping on them).
The challenge is to find a way that will provide sufficient aeration to the slurry so that nitrates are in check and nitrogen, potassium, phosphorus, magnesium, boron, calcium, manganese, zinc, copper and molybdenum are available to plants. There are a couple other blogs out there that suggest using a biofilter like with aquaponics, but why not try experimenting with some different systems to find which may be a good "match" for growing with bioslurry in a way that is easy and duplicatible. Growers monitor the nutrient levels in the water with an electrical conductivity meter. When working with biopoincs we are measuring success by the color, shape, size and overall health of the plants because electrical conductivity will not register with slurry in a meaningful way.
I will be posting on my success using a system the Tower Garden over the winter while growing indoors over the winter with T5 lights. I will be doing a few grow cycles: the first will be at 10:1 ratio of slurry to water on continuous run without any mitigation to the slurry. The second grow cycle will be a 10:1 ratio of slurry to water, but the slurry will be mitigated for two weeks with a system called the Bucket Vortex which is a super aeration bucket machine with a bio filter. I will measure if the plants are healthier with the bio filter vs. no bio filter by observation of plant physiology, disease, and overall health.
Here are my favorite matches for the systems I listed based on plant physiology:
NFT: Fast producing leafy greens such as lettuces, Bok Choy, and perslane
NFT/Deep Water Hybrid: Kale, Swiss chard, and Basil
Deep Water: Tomatoes, Kale, Swiss chard, basil
Coco logs via drip irrigation: Beans, peppers, and cucumbers
Coco in flood and drain tray: micro greens, wheat grass
Tower Garden by Juice PLUS: Grows just about anything besides beets, onions, and any enormous tubers. WORD TO THE WISE: Although you can grow almost anything in the Tower Garden, mono cropping and separating fruiting and flowering plants from leafing plants is ideal for ANY hydroponic system because fruiting and flowering plants require a 1:2 ratio of nitrogen to minerals and leafing plants require more N with an even ratio of “A” (nitrogen) and “B” (minerals)
The Tower Garden is the “no brainer” choice for growing with bioslurry because it does not have the little sprayer heads that often get clogged with standard aeroponics and it can be turned on continuous run to maximize O2 to the slurry/water mix and agitation.
Please feel free to leave your comments below on any system that you have tried with using bioslurry and share your story and pictures of your plants. The more we share, the more we empower!
Let the indoor growing experiment begin!
According to David House's book on biogas, one of the toxins produced in the gas making process is ammonia. To mitigate that, I decided to leave the pump for the Tower on continuous run to try to "air it out". I also found that the water in the rain cap on the top of the tower overfills. However, a quick fix is to leave the lid cracked to equal the pressure so that the overflowing doesn't happen. Week 3 is going to be the "proof in the pudding" as the plants are no longer seedlings and need more bioavailable nitrogen. The is NO biofilter in use right now to mitigate ammonia or nitrates. I want to see if the use of a filter can be skipped. Please place your comments below and theories as to why the water inthe rain cap builds up when sealed. Is it trace amounts of gas? Please share!!!
Is this the type aerator? Never seen ref to it. I was thinking swirl-filter, but that doesn't aerate. This just recirculates within the bucket and pipes, with air to lift and circulate the water.
Same general idea, then. The one you show has a pump for liquids, the one I found uses air. Yours also gets a 2nd aeratio, while it drains back into the larger container, beneath.
With all the talk of mixing digesters, yours would probably work better, since it can spray on top of the scum layer, to help keep it mixed in, rather than allowing it to form, in the first place... ;)
The plants have been grown exclusively on slurry from my anerobic digester and water for 5 weeks (I.e., 2 weeks in the grow tray and 3 weeks in their respective growing units. The plants are looking great without any yellowing to the lettuces, which is a sig on N deficiency. Minor issues include some discoloration of the Kale possibly because of the grow lights and a cole of leaves had some powdery mildew that I found on a nearby house plant I recently brought in. I am going to treat that by pinching off the couple of effected leaves and keep going. Someone had a great question this week about pasteurizing the slurry before using it to kill possible pathogens. I refer them to TH's char on temperature and time which kills any nasty bugs. More pictures next week!
Notice the difference in less than 1 week of growth!
The plants are still looking good. I am not noticing anything that looks leggy, nitrogen deficient, or mites. There is a little bit of powdery mildew on some of the leaves, but it looks good. I added more 10:1 ratio of slurry to water during this week. If there is any nitrogen deficiency this is when it would be seen because as the plant matures, it's requirement for nitrogen increases.
Overall, I am pretty happy with how the plants did in the 10:1 ratio of slurry to water.
Parameters for the Tower Garden: Slurry and organic material is not inertly ionic, so I chose to have the pump on continuous run rather than the recommended 15 min on/45 min off for indoor growing, which possibly contributed to the issues some of the plants had which included browning at some of the leaf tips and a powdery mold.
Other mild issues included some leggyness and decrease leaf thickness with some paling which is a sign of decreased N pick up.
The plants that did well in the Tower Garden included the lettuce mixes, purple lettuce, bib lettuce, and Swiss chard. Plants that did not do well included the purple kale.
For the deep water, both plants were looking good with their 10:1 ratio of slurry to water.
Conclusion: Overall the plants did well in the 1-4 weeks of grow cycle, leggyness and paling may have been due to increased nitrogen needs of the plants, powdery mildew and possible fungus attack was due to having the water on continuous run.
NEXT STEPS: Remove all plants, clean down the Tower Garden, and start a new grow cycle with at 10:1 ratio of slurry to water with a large bubbler at the bottom of the Tower Garden to keep the water agitated and run the pump supplying water to the plants on the recommended 15 min on/45 minutes off for indoor growing.
Simply doing some plant maintence and changing the on off cycle of the water pump to my plants has paid off! There are so many factors besides NPK to consider when it comes to growing healthy indoor plants. Having water temps above 70F is a plus, a daily light intergal of 17 for lettuces (i.e., adequate lighting), humidity, moisture, under or over watering, CO2 levels, etc., so it can be neglectful to just say it was the "slurry." We are doing real science I our living room without a spectrometer, just using our eyes. Check out our plants and please share what your eyes are telling you about the health of our "Homestead Ecosystem".
All looking great Kathy, fantastic to see you doing some authentic agro-science! Many think thats a defunct concept these days, you prove em wrong!
I wonder, have you been monitoring the input to the digestor ? It may be interesting to begin to monitor the effects of different 'slurry types' to the outcome (ie healthy happy plants)
Seeing this I am quite excited to share with Peter Hanappe of www.p2pfoodlab.net , these folk would be very interested.
Personally I'm not one for the indoor unnnatural light thing...its odd enough that the roots aren't in the ground and somethgin of a leap for both the plants and for me to comprehend, something of an evolution characteristic of the times maybe...
Looking forwartd to going vertical and joining the research crew, would be great to add the sensor tech of p2pfoodlabs to monitor, could be a synch-up there that would allow us all work independently , but together, and trial for optimal in our respective contexts.
At the beginning with the best of feet forward, a community effort all round.
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