Tom Turner

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since Jun 03, 2011
high desert and mountains of Idaho and coastal Atlantic Canada (migratory)
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Recent posts by Tom Turner

One factor to consider is the temperature of the greenhouse. If we allow the temp to get very hot the greenhouse becomes a powerful evaporator. If the temps are kept low by heat-sinking to a thermal mass it becomes a poor evaporator.

I think with some carefulness I think plants can be house-trained. Incorporate these:

<> efficient heat transfer to a substantial thermal mass

<> keep all soil well mulched

<> drain all catch pans

<> avoid over-watering,  which I think people tend to do to help the plants survive the massive heat of the "hot house", which if you control becomes a non-issue.

<> good ventilation (and not just for the plants, we need ventilation also). Install a heat recovery system and exchange 4-500 CFM.
1 year ago

Kevin Wang wrote:House exterior walls are not waterproof. If you have super high humidity air on the outside, it will make its way into your house's walls and feed mold, rot wood, etc. cement is not waterproof. stucco is not waterproof. wood is not waterproof. tar paper may be pretty waterproof, but usually when the side of a house is layered with tar paper, kraft paper, or house wrap, it's layered, much like shingles. it's designed so that gravity will pull water droplets (i.e. from rain) away and out from the building. If you build a greenhouse, humidity is air, not water droplets, and will happily go upwards into your house.

I would not recommend an attached greenhouse, because of the humidity.

An attached/enclosed porch is different, because there is no moisture.

Kevin I think you exaggerate humidity's ability to pass through vapor barriers. If it were true then greenhouses would never accumulate humidity, they would just release it to the outside air.

But I think I'm the other way. I want to trivialize humidity.

1 year ago
Isn't it possible to minimize moisture loading by mulching everything. I also thought that it wouldn't be too difficult to drain all the catch pans into a container and recycle the water.  I tend to think about the ideal of living with your garden. We give them love; nutrients; water and CO2. They give us Oxygen; psychological warm-n-fuzzy feelings and food.
1 year ago

David Maxwell wrote:...  The pumps to pump the water through the radiators (my "heat exchangers") are controlled by a differential thermostat, so that they run only when the temperature of the air, (in the peak), is higher than the temperature of the water.  It was apparent that the heat was coming out of the water in the tanks reasonably efficiently, as the temp in the tanks drops as much as 20 degrees C overnight.  But I have gilded this lily a little - I am pumping the water through black plastic piles buried  8" down in the growing beds, 24 hours a day, (at least when the cheap pumps are still working).    I did this on the principle that heating the plants' toes made more sense that trying to heat the entire volume of air in the greenhouse.  But it had an unexpected effect - it added the soil in the growing beds to the thermal mass.  The temperature in the tank with a functioning soil pump runs about 2 degrees lower than the other one, and the soil temperature in the the "circulated" beds, runs 2 degrees higher than the ones without circulating water.  In addition to the pumps, I have 4 large computer fans which draw the air from the peak through the radiators.  All these  pumps, fans and controllers run off a 90 Watt P-V panel with a small battery storage (actually the battery from my ride-on mower) which carries the  soil pumps through the night. Obviously, since I am able to quote these temperatures, I also have a monitoring system capable of storing a log of data drawn from, (in my case), 4 separate channels..  (Mine currently polls the temp sensors every 10 minutes).

NICE! The heated beds is an awesome idea. I'm not a biologist but I think soil temperature sends signals to the plant to tell it how and when to grow. It at least is vital in seed starting and I know high soil temps tell the plant to go dormant until it cools off a bit. You have designed a "task heating" system (like "task lighting"). Heat only where and when you need it, not heat always everywhere. Only through active systems can you achieve this ideal.

Now that you have the (active) components in place you could add a compost pile into the system, extracting heat from the decomposition and giving off some co2 to make happier plants. and once again serendipitously adding some more thermal mass. Because you have an active system the compost pile need not be in the green house, just nearby connected by two pipes and a vent duct.

David Maxwell wrote: Does movable thermal curtain insulation count as "active"? (That is my next "refinement", after I get, and install, some new pumps, which hopefully will last a little longer.)

Well we had been talking about active/passive in heat transfer systems. Movable insulation is more of an adaptive system and yes it would be an active adaptive system. An example of a passive adaptive system would be deciduous trees on the south side of your house, they adapt from shade in the summer to sun in the winter.

The Chinese consider roll-up thermal curtains as essential. See that article I posted above. What I think the ideal would be is insulated shutters of some sort that when open become light-gathering reflectors.  Stand on the north shore of a frozen lake and you get twice as much sunlight - direct from the sun and seemingly just as much reflected off the lake.

I read many years ago about movable insulation with ping-pong balls filling large cavities between sheets of glazing. He moved them in and out with a blower and duct work. It at least would be a show for guests - as soon as the sun sets these balls start filling-up the windows.  
1 year ago

bob day wrote:Great Links Tom, very informative. I've been puzzling over how to grow figs and actually get a good crop, looks like the fruit walls are the solution. I had no idea they were so effective, or had such a long history

Thanks. The article doesn't say, but by the pictures I think the reason they are so effective is that the fruit trees are trained to grow right against the wall, cuddling to keep warm.
1 year ago
Good post David.  There is an underlying ideal at work here even if people are not conscious of it, that is Active vs Passive. Especially in a perma-culture setting Passive is always first choice and Active has a bad image of being overly complicated.

But active, as you know, can yield huge performance benefits.  I think that a "properly" designed thermal mass storage system would have an active deposit system as you have engineered, and also an active withdrawal system which would then become computer controllable. There is no efficiency in heating a space when it doesn't need it. If it is indeed a storage system the mass should also be insulated to extend beyond only day to night cycles but also to compensate for rainy day periods.  

All of that is also applicable to rocket mass heaters which would benefit from becoming Pro-Active.
1 year ago
The history of greenhouse thermal mass is kind of ironic. We began with nothing but thermal mass, in the 1600's northern Europe called them fruit walls:

Then we discovered that adding some expensive glazing really helps:

Then we became spoiled by abundant energy, energy to waste (not just in the energy to make glass but also to heat the greenhouse) and then went here:

Now we have forgotten where we began and don't quite understand how thermal mass works.

Great article on fruit walls and Chinese greenhouses.

1 year ago

Gilbert Fritz wrote:One interesting way to grow organic matter for a plot is with azolla ferns in a pond. Azolla fixes nitrogen from the air, so you would be importing nitrogen and carbon. The pond will only benefit from removed nutrients, not suffer. And the azolla mat makes a good weed smothering mulch. Azolla is one of the fastest growing plants on earth under ideal conditions.

Azolla?! I grew some fast growing Asian poplars (andrascogins). One grew to 16 inch diameter in three seasons (at it's base there were a couple raised beds which didn't get tilled and the andrascogin sent it's roots UP into the beds and quickly root-bound them. I've thought andrascogins might be a good way to turn human poo into firewood. But a better way would be a global market for home grown textile hemp raised on human poo. My grandmother would bring the wool from the few sheep they had to the local woolen mill in exchange for yarn. If we had a socially organized system of poo to textiles, and a hard-working diligent woman who would make me clothes -custom tailored clothes- on her high-tech sewing machine working from computer-generated patterns. That would be living large on appropriate technology.

I could live my whole life without ever consuming any of the by-products of that 2000 mile swath of corn and soy bean along I80.  But what I would really love to have is a four season greenhouse supplying me kale and other greens, but mainly kale, all year long. And I would love to have fish three times a week. My Dad said that when he was a kid in rural Boston fish was a poor man's food. Kale was the traditional poor man's food in England, "kale yards" being a somewhat derogatory name for slums. I would love to eat fresh kale and fish three times a week, but, ironically, today it's too expensive. I've thought about if that could be a symbiotic system with the fish (vegetarian tilapia) and hydroponic kale sharing the same water. But I don't have the soil nutrient and aqua biology knowledge. It seems that the hydroponic kale would want the water dirty with nutrients and that the fish would want the water kept clean of their "ahem..." nutrients, which usually demands a high exchange of fresh water, making fish farming not that attractive.  

I'm rambling here. My point/question is: Would Azollas grow in the relatively clean water of a healthy tilapia pond, the moment a tilapia relieves himself there is an azolla root to immediately take it up. The azolas keep the water scrubbed clean and then are harvested to provide rich soil nutrients which then grow the grains to feed the tilapia. Kind of a closed-loop symbiotic system to turn CO2 into protein.

Gilbert Fritz wrote:I'm glad you liked my website! As always, when soil balancing comes up, I'd recommend Steve Solomon's book, The Intelligent Gardener. I disagree with him on some things, and his tone can sometimes be off putting, but it is the best book I've found yet for small scale growers looking to balance their soil.

The objectivity required to separate an idea from an off putting source is admirable. Kudos. Quite often the opposite is true, often people want to know the source of an idea before they form their judgement about it. That is a negative aspect of the academic principle of citation. It, perhaps unwittingly, forms ideological camps. The ultimate test of a truly courageous objective thinker is one who could quote Adolf Hitler (surely he said something quotably good). I can't do it though, I don't have the courage. I've had too many ideas rejected out-of-hand because of my own off-putting-ness or the pigsty where I might have found such a pearl of wisdom (E.G. quoting GK Chesterton or Eric Hoffer in a forum of high-brow intellectuals).

2 years ago
Thanks Gilbert. Now I get the 'pulse" thing. And I like it. You, and your website, have also taught me about the balance of nutrients and the possibility that you might over-amend with certain nutrients. I had always seen it kind of like taking vitimins, if you take too many you simply urinate the excess out. A gram of vitamin C turns your urine a festively bright shade of orange. It seems to me that soil analysis should become an indispensible and integral part of agriculture, agriculture that is, that feeds their crops with their soil instead of with chemical spray tanks. The industry of inexpensive laboratory soil analysis should be a growth industry.  

Apologists for our globalized industrialized agricultural system, where it is the norm to eat foods grown on the other side of the world, make the argument that it is more healthy because we get a more balanced diet. They claim that in the bad-old-days when people ate only foods which came from the same patch of ground that deficiencies were common. If I remember correctly iodine deficiency is the common one cited. If the movement to grow and eat locally takes off then we may need to move certain nutrients around because the balance of our diets come from the balance of our soils.

In the middle of the so-called fly-over zone, say in the middle of Iowa, it would probably be difficult to find organic material without paying market price for it. But in urban areas there is an abundance of organic material, the product of aesthetic landscaping. Marcos seems to be very successful finding organics in LA at a very cheap price. (He might give credit for his soil fertility to his herd of long thread fungi but I think it is the 8 inches of wood chip he top dresses with every year.) In urban areas landscapers are always looking for dumping places for their organic waste (except beware the chemical rich grass clippings which have even more chemicals than what we eat out of the grocery stores). If we move towards urban/rural desegregation, then the market for alien organics opens up. Full integration might be two acres per family, 1 acre pasture bounded by wooded hedgerow, 1/2 acre garden and 1/2 acre aesthetic landscape surrounding the house which also incorporates a massive green house. People should live with the flora and fauna they intend to eat ... but no chickens in my bed, only dogs.

2 years ago
To till 1 foot and to mow at 1 foot is that root-to- soot ratio which concentrates organics in that 1 foot? Does the same thing work with lawns which get continually cut at 1 1/2 inches?  Or the golf course "greens" which get cut to like 3/8 inch?

Doesn't nearly all organics come from "outside" a soil? Isn't the vast majority of the mass which makes up organics taken from the CO2 in the air?  Photosynthesis assembles this CO2 along with water and trace minerals/chemicals/nutrients into organic matter. Carbon is the stuff of life. This matter can be converted into other forms of life.  -or converted back into CO2 in waste treatment facilities. In a strange abstract way the entirety of the system of agriculture, which includes all farm land and all grazing land might be seen as a way of "feeding" our waste treatment facilities (i.e. CO2 production facilities) with the human being as just one step in that process of converting life back into carbon.  Don't try to find a point in all that. It's just an observation.

Join me in emoting. See the powerful film The Field. Here's the opening scene: "God made the world. Seaweed made that field."

Seaweed soil amendment is not a feel good myth. It is a historical reality. See the documentary shot in 1934 when this lifestyle still existed.

2 years ago