Has Agriculture Reached Its Peak?

[DarkBlack]

"Maine is ideally suited for greenhouses, because it is easier to heat up a greenhouse in the winter than it is to cool it down in the summer -With the new greenhouse, the company will almost double production from about 75,000 pounds of tomatoes harvested per day to about 150,000 pounds.
- See more at: Hydroponic tomato grower expands with 75 new jobs in our backyard
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You, of all people should know that's a crock...
A future greenhouse in Maine simply needs to be designed to be open-able in the summer. No fuel required.
Frigid -15F winters requires a lot of energy to keep warm. oil, gas etc...

 

[dave1949]

Yea Coleman pioneered a lot of that stuff. I have his last book and one another.

I don't grow thru the winter at all. Most of my herbs and such go well up to thanksgiving uncovered on an exterior porch. Celery, parsley, sage, oregano, rosemary all did good for a long time. Even at the flower greenhouses the early cost are phenomenal. They keep it a bare minimum this time of the year one seed starting and incubator house going then the tomato house, plus one other flower house. Others open one at a time etc . We gave up on taking strawberries thru till the December Holiday Farmers Market...people loved them but again production just doesn't support the cost. Other problems are low light conditions that time of year slow downs growth. U MASS recently published an article saying how northern greenhouse production of tomatoes wasn't profitable under most circumstances for growers after monitoring production for many seasons. I see if I can locate it. Ha I always knew my boss wasn't making money on it!

Got it...

http://extension.umass.edu/vegetabl...es/newsletters/Feb 6 2014 Vegetable Notes.pdf

If you could have cheap heat and reasonably cheap light, you could extend your crop seasons.

There has to be a way. The right building technology, pellet or biomass-fired boilers using local wood products, solar electric to reduce the winter lighting costs.

I'm fairly sure I could accomplish that on a home greenhouse scale. There would be some significant one-time construction costs to amortize. Maybe that is the problem. On the other hand, look how much capital investment is in Backyard Farms in Madison, Maine. They grow organic hydroponic tomatoes year-round.

 

[DFB]

If you could have cheap heat and reasonably cheap light, you could extend your crop seasons.

There has to be a way. The right building technology, pellet or biomass-fired boilers using local wood products, solar electric to reduce the winter lighting costs.

I'm fairly sure I could accomplish that on a home greenhouse scale. There would be some significant one-time construction costs to amortize. Maybe that is the problem. On the other hand, look how much capital investment is in Backyard Farms in Madison, Maine. They grow organic hydroponic tomatoes year-round.

Yea I just reread that link that is a massive scale for production to justify the end result. I have to wonder...sometimes business operate in such non stop cash flow in/ cash flow out fashion that is true profit ever being realized. The greenhouse flower/produce business easily operates in such a fashion carrying constant revolving overhead in material, continuous infrastructure repair and replacement, payroll, vehicle, and energy costs. Nature of the business? As they joke...keep farming until the money's all gone!

You think about heat in a greenhouse. All that space being heated. Tables are probably at the 3 ft mark. Heating elements located beneath the product would put the warmth into the soil root zone (same as radiant tube heating under a ground bed.) Then the heat could be trapped in smaller overhead structure assembled over the plants than using all the greenhouse itself. No need to heat ALL that space to same temperature. A greenhouse within a greenhouse...write it up apply for the experimental grant money

 

[dave1949]

Yea I just reread that link that is a massive scale for production to justify the end result. I have to wonder...sometimes business operate in such non stop cash flow/in cash flow out fashion that is true profit ever being realized. The greenhouse flower/produce business easily operates in such a fashion carrying constant revolving overhead in material, continuous infrastructure repair and replacement, payroll, vehicle, and energy costs. Nature of the business? As they joke...keep farming until the money's all gone!

You think about heat in a greenhouse. All that space being heated. Tables are probably at the 3 ft mark. Heating elements located beneath the product would put the warmth into the soil root zone (same as radiant tube heating under a ground bed.) Then the heat could be trapped in smaller overhead structure assembled over the plants than using all the greenhouse itself. No need to heat ALL that space to same temperature. A greenhouse within a greenhouse...write it up apply for the experimental grant money

People have built "pit greenhouses." From covered dirt pits to something more refined.

If this design was earth-bermed on the back and the rear half of the end walls, it would be a good start. Figure out the night time insulation of the glazed area, and you would be most of the way home for very low cost heating.

 

[DFB]

People have built "pit greenhouses." From covered dirt pits to something more refined.

If this design was earth-bermed on the back and the rear half of the end walls, it would be a good start. Figure out the night time insulation of the glazed area, and you would be most of the way home for very low cost heating.
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Yes a very efficient design, a heat sink. You know back before I was an outlaw and I was still farming with my ex inlaws we had over 60 feet of a fiberglass walled rough cut spruce wood framed greenhouse not even the double or triple wall polycarbonate stuff you get can now and it was heated with under the table cast iron radiators scavenged at the time from a fuel dealer scrap for free. Hot water came from a wood/oil combo boiler located in the basement of the home heating both the residence and the greenhouse. The excessive extra heat in the basement around 75 degrees most of the time allowed for excellent seed starting and growth with grow lights prior to moving to the greenhouse. The greenhouse was divided in half with a door/wall to control how much space was in use at one time. Located on the south side of the house cold frames were assembled against the basement wall and the windows allowed the heat from the basement boiler to migrate into the cold frames and small fans helped with circulation. I swear more thought went into this than the house itself.

 

[dave1949]

Yes a very efficient design, a heat sink. You know back before I was an outlaw and I was still farming with my ex inlaws we had over 60 feet of a fiberglass walled rough cut spruce wood framed greenhouse not even the double or triple wall polycarbonate stuff you get can now and it was heated with under the table cast iron radiators scavenged at the time from a fuel dealer scrap for free. Hot water came from a wood/oil combo boiler located in the basement of the home heating both the residence and the greenhouse. The excessive extra heat in the basement around 75 degrees most of the time allowed for excellent seed starting and growth with grow lights prior to moving to the greenhouse. The greenhouse was divided in half with a door/wall to control how much space was in use at one time. Located on the south side of the house cold frames were assembled against the basement wall and the windows allowed the heat from the basement boiler to migrate into the cold frames and small fans helped with circulation. I swear more thought went into this than the house itself.

Well, there you go. Update that basic idea a bit with modern materials, some added thermal mass in a concrete slab, some earth berms, and that would work.

Judging from my passive solar house, that design of greenhouse I showed would probably hit 100*F+ inside on a sunny day in winter. You would have to dump some heat on those days and have a way to open it up in summer. I think some automation is key to doing it well enough to avoid stressing the plants.

The concrete itself will stay at some fairly stable temperature that changes very slowly if there is enough of it. It works like a flywheel that has thermal inertia.

I am always tempted to start gathering building rocks. I have some mostly south facing slopes to work with.

 

[DFB]

Yes you really do need to monitor the heat in a greenhouse. Most fan ventilation systems are thermostat controlled. They do have thermal activated vent openers I believe. It doesn't take much a little sun closed doors and vents and things can overheat in a hurry.I remember one year the FIL took off for the tractor store or somewhere one rainy morning and while he was gone the sun came out and a lot of my tomato transplants were still closed up in the cold frame. Heat stress did most of them in.

 

[bmaverick]

Ground air thermosiphon greenhouses can easily take on winter temps down to 20F at night and use the sun solar during the day. Not sure if Maine can do this, but in TN it's popular. Temps stay above 50F at night and 70+ during the sunny day.

 

[dave1949]

Ground air thermosiphon greenhouses can easily take on winter temps down to 20F at night and use the sun solar during the day. Not sure if Maine can do this, but in TN it's popular. Temps stay above 50F at night and 70+ during the sunny day.

Never tried those but they look useful. How well do they thermosiphon when there is no sun on the exposed collector panel? It seems like a night time or cloudy weather cold air circuit directly into the base of the rock bed would be better than sending it to cool off in the panels before passing through the rock bed?

Snow cover might be an issue here. It would probably pile up at the bottom, then work it's way higher, melt, drip down and freeze into a mini-glacier. :laughing:

 

[forgeblast]

The pit green houses and Solar thermal green houses are great for the northern areas. The solar thermals (ST) have a solid north facing wall to avoid heat loss and also have thermal sinks like water barrels painted black on that north facing wall to radiate out heat. The st I want to build will have air forced into the ground through perforated pipe and the barrels. It will be a few years before I get started on it though.