|Conventional Potting Soil Test|
In order to discuss problems with Pocket Gardening, I first have to briefly talk about potting soil and validate the information. I will use the experiment in this picture. The above picture is of a potting soil test with mixtures of more conventional potting soil. These consist mostly of peat moss with compost manure and or forest products & a little top soil. Each vertical chamber in this Vertical Eco Garden, having 5 pockets on the front, has a different blend of potting soil. The only soil that was significantly different is the middle row. Row 3 started out of the gate strong but finished last. Visually, the soil in the first row looked like what a novice (me) would consider a nice rich earthy looking soil. It was rich, moist and beautiful. However, this produced a smaller compact plant with more secondary growth between the main branches & smaller peppers. The second row received potting soil that was used the previous year, and it was amended with a product called Organic Garden Tone by Espoma. The 2 main Ingredients in Garden Tone is Hydrolyzed Feather Meal and Pasteurized Poultry Manure. Since this was re-used (amended) potting soil I will touch on information on how to do that and then we will get back to the experiment.
I have seen directions for amending potting soil that required heat treatment in a clear plastic bag to be placed in the sun for X time at X temp to kill microbes. Then it said there were good and bad microbes but didn’t explain how to discriminate. The short answer, not found in the article is that bad microbes can live in compacted soil with little air because oxygen is of no use or is poisonous (anaerobic) and will inhibit or kill them. The friendly microbes thrive on air and produce stimulating root growth hormones and beneficial trace elements like nitrogen and phosphorous. The article said to add more perlite for aeration & vermiculite for more water retention. Instructions for testing drainage VS water retention said to pour water in the pot and see if it drains and how fast. This information was all after the fact regarding our test. Regardless of this, the second row did good. I think it was because we simply amended (re-mixed) with a bio-intensive plant food, and planted an heirloom that was smart and tuff. The reasoning was, if the potting soil worked the year before, it just needs nutrients and cultivation (loosened- up). The third row was an expensive $40.00 per 2 cu ft bag to be used for growing what used to be a weed, but now is a medicine. The Master Gardener in charge of the experiment thought it looked like the peat moss was too fine and would compact. The fourth & fifth row did the best. The forth row is called All Pro and is a Michigan based company that was purchased from a garden center in Byron Center Mi on sale for about $7.00 / 2 cu ft. It contained a lot of composted forest products. The fifth row was a home -made mix and had a lot of composted leaves with a little top soil. All of the soils used different amounts of perlite for aeration and we added Garden Tone to all of the soils as well. So, all of the soils had the basics of a potting soil described in the following, more or less. The first ingredient I will mention is the main medium, It is the bulk of the potting soil. The functions are to provide the plant roots with a home that will hold a good balance of air, water, food and stability (root anchorage). For this, Peat Moss has been the main source for a long time. However, other medium & sustainable types have come of age. Coir is probably the most used to replace peat moss because it has very similar properties. Some a little better (less compacting) & some a little less, (water / nutrient retention) but this isn’t rocket science if growing heirlooms. For a sustainable to replace peat moss go with Coir that is made for growing plants and not for bedding or as feed filler and just add a little more plant food per the same directions on the label.
The next amendment is compost. Compost is decomposing organic matter like manure with bedding of straw or wood shavings, or chicken manure with rice hulls or wood shavings (chicken liter), and forest products (leaves & wood etc).
Ideally, any compost will contain a full range of materials in different stages of decomposition from chunks to what looks a little like muck. This is the humus content, it is the residue from advanced stages of decomposition. Humus will hold 90% of its weight in water and it gives the soil stability for root anchorage, but it has little to no nutritional value. If your compost is too chunky and drainage is too high, vermiculite is added to retain water. If it is too mucky, add rice hulls, perlite and coir or peat moss along with plant food. Most of the compost should be in the middle. Not too fine or muddy and not too chunky. A bag of potting soil / compost should not be heavy and wet. What is desired is organic material that is decomposing (good microbes), not decomposed or not decomposed enough (nitrogen lock up). Chunks of wood for example, should be fingernail size and be able to crumble between your fingers. A few small sticks are OK for resisting compacting. The finer particle (humus) will typically compress and form when pinched between your fingers but a handful of the potting soil should not form or clump together when compressing a handful. This would indicate the humus content is too high. The next amendment is for air or aeration in the soil. Traditionally, this has been perlite. It usually makes up 20% to 25% of the mix. However, we’re about to change that with rice hulls.
For aeration, Rice hulls are the new kid on the block and this is what I want to talk about.You may have heard some bad reports on rice hulls. Well, there’s a reason for that. Rice hulls are either boiled or un-boiled. Boiled rice hulls are used by the nursery industry to replace perlite. I think this is preferred by their customers in the big cities who don’t want to deal with floating perlite in managing waste water, treatment and run off. Riceland learned the hard way on how to perfect boiling rice hulls. The problem was this, Sugars & starches are the first to break down in decomposition. When that happens it takes nitrogen from the soil (nitrogen lock up) So, Rice hulls used for aeration took nitrogen from the plants and then it decomposed too fast. I suspect this may have caused them to lose structure and resist compacting. With less nutrients then less aeration, the plants were stunted. The relationship with aeration and nutrients is this. Granted, roots need air, but so do the microbes that have the job of breaking down the organic matter and provide food. So, aeration is key. To fix the problem with the rice hulls was to boil the starch and sugar out of them.
Even this process had a learning curve. It required replacing the water between batches to get rid of all the sugar and starches. What is left behind is a SILICATE like hull shaped material, that now, free of sugar and starch, will not take nitrogen from the soil and will decompose more slowly while holding the hull shape to provide aeration. Here’s my thinking and here is how I want to incorporate rice hulls in the Vertical Eco Garden. Granted the boiled rice hulls are free from sugar and starch and are now a silicate structure, but are still organic, and it will eventually decompose. Although it doesn’t have the sugar and starch content that locks up nitrogen, it will still absorb nitrogen (nitrogen Lock-up) in a saturated treatment to initiate decomposition.
Regarding Pocket Gardens, We realize the Vertical Eco Garden resemble a pocket garden. And this is a problem because Pocket Gardening doesn’t work as well, especially for growing vegetables. In fact, we are the opposite in functionality. From ALL the pictures of pocket gardens I have seen, they must be using heavy compacted soils. Because the plants resemble our stunted pepper plants in the heavier, more compacted media in rows 1 & 3. My position is pocket gardening relies on heavier soils in an attempt to get root anchorage so the plants would not blow out in the wind also preventing the soil from drying too fast in their fabric. This is the another pocket garden issue. I won’t go into all the engineering water flow specs for Geo materials because that tends to get a tad boring. However, I will just say they are being misunderstood and are being applied backwards in most cases.
|Mechanical Root Anchorage|
Basically, in pocket garden materials the water flow specification of a filtering application is being applied to a drain design. So the water runs out too fast. To compensate, they go with either more humus or too much vermiculite. To make matters worse, they have resorted to combining organic (cotton, hemp, etc.) materials in the construction of pocket garden material to absorb or wick water. These won’t last long either, in or out of doors because they will become plant food. The Vertical Eco Garden goes in the opposite direction. Our roots anchor when they grow through the UV resistant geo material from the small pocket into the rooting chamber. This chamber can now use loose aerated mixes of medium. Water is utilized by using only one dripper set on low to feed the 5 growing stations below. This is a drain design application. This, along with root anchorage is the key difference. For example: When bush beans are planted, 15 plants will be watered by one single drip irrigation component.We are focused on our mission to get the biggest yield from the lowest cost, from the smallest volume of growing medium in the least amount of space.Growing vertical is just the natural consequence of that. So, another question that fits this mission statement is, why can’t the same amendment for aeration (boiled rice hulls) be used for a portion of the compost as well, increasing both aeration and microbial nutrition. The potting soil test indicates this is the direction to go.
I was looking at a back yard garden composter in a farm supply magazine. It showed a barrel full of what looked like oak leaves. I prefer Maple leaves. The advertisement said it could compost leaves in 15 days and it would contain the odor even with a rich nitrogen additive. So, in the same way as is practiced to decompose leaves we are initiating decomposition of boiled rice hulls. So far, they are decomposing. We think we can control this to the mid way point of decomposition. We don’t have big chunks and we won’t have the sludge (humus) because we are starting with a more uniform material. These little hulls will still work for aeration because so far, they are holding much of their shape. They don’t break apart, crumble or turn to mush.
The Vertical Eco Garden is currently getting high yields from 25 to 75 short to mid size heirloom varieties in only 6-7 cubic ft of potting soil, using a garden space of 5 sq ft. However, we’re pushing for vegetables from 90 heirlooms. This will be the results from having mechanical root anchorage in a loose non compacting aerated microbial rich potting soil. We’ve replaced heavier soils for a more aerated medium that provides a more bio-intensive environment. We have combined the best of aeroponic, hydroponics and geoponic in one system. Vertical Eco Garden has found ways to improve this by utilizing the rice hull amendment not only for aeration but also to extend the growth life of the potting soil. Theoretically, this is done by manipulating nitrogen lock up in the boiled rice hulls before it is added to the soil. Then it will provide both aeration and bio-intensity which work hand in hand. It just makes more sense. But let’s not stop there. What about rice hulls for water retention? Visualize this, Peat moss absorbs water like a sponge. In your head, do this little experiment for. Take a sponge and let it absorb as much water as it can and ring it out in a small bowl. Then let that sponge absorb water again and lay it on a dish. Which one will dry up faster? The water in the bowl (rice hull) or the water in the sponge (peat moss)? If you guessed the water in the sponge you are correct. Theorizing rice hulls can do more of the main functions of a potting soil, we are going to do another growing media test.
Mini VEG™ Vertical Eco Garden™
The picture on the right is our Mini VEG 9. It has three vertical rooting chambers. Each chamber will receive different percentages of rice hulls as a growing media. One will have 100%, the middle will have 75% and the third will have 50%. All of the same bush beans will be planted as a control perimeter. We will be sure to keep you posted.
The 2 pictures below are the growing stages and results of the potting soil test pictured at the beginning of this article. It also demonstrates big plants can come from what looks like a small pocket. But make no mistake, this is NOT pocket gardening.