South Field Plateau Greenhouse – The Ark
Ten days ago we pulled the tarp up and and over the south field greenhouse. The greenhouse doesn’t look green yet since it has the initial winter tarp rather than the clear plastic we’ll put on later but the pigs are enjoying it.
Old South Herd Nest and New South Field Plateau Greenhouse
The weather had gotten too cold to pull the clear plastic so this year we put on a billboard tarp (BillBoardTarps.com). That will get us through the winter until we can put on the clear plastic in the warm summer months when the plastic won’t be damaged by handling in the cold. Someday we’ll replace that clear plastic. By the time that happens I hope to have the money to do it with either kalwall fiberglass or twin-wall polycarbonate. The FarmTek frame can handle all of these different cover types.
Pigs Walking Winter Paddock Trail from Greenhouse to Whey
When Kimsa and I went out to check the pigs this morning most of them had already left their nest in the greenhouse and were headed north along their roughly 1,000′ long trail to the water and whey. Spitzon, the southern boar, was walking along the line checking each of his sows as they went by.
Open South End of Greenhouse for Ventilation
The north end wall blocks the cold winter wind, a pretty continuous thing here on the mountain. You’ll note that at the east and west corners of the wall we’ve left openings for cross ventilation – a necessary element even in our cold climate to make sure there is fresh air throughout the greenhouse. If need be I would also open a window up at the peak in the north wall. For now I’m observing to see if that is needed. We’ll fine tune the system over time.
Pigs in Communal Nest
The floor of the greenhouse is covered with a two foot thick pack of wood chips which composts to create heat rising up from their deep bedding pack. The communal nest is about 80°F. Nice and cozy even with our deeply negative winter weather.
Hoar Frost Snow on Rope
The moisture rises up in clouds from the bedding when the pigs rise in the morning. The 21′ ridge line lets this rise clear of the animals so they are getting fresh air throughout the greenhouse and the bedding is staying well dry. I am seeing some condensation on the tarp in the top two panels by the ridge line along the entire length of the greenhouse but it is not excessive and there are very few drips. It seems to mostly condense, freeze and then sublimate away rather than building up. A problem we had with smaller greenhouses was that the moisture condensed on the plastic and rained down on the bedding from the short height. In those smaller structures the cloud was low to the ground and couldn’t escape as easily. The height of this greenhouse seems to solve that problem as I had hoped it would.
I put the black side outward on the tarp to increase solar gain and snow shedding which let me put the white side inside for increased light. On the exterior we are not getting a build up of snow. The greenhouse has a heavy duty center ridge pole with seven supporting posts so that it should hold up to any snow load we would get. My math says the center posts should hold up to 300 lbs per sq-ft in addition to the strength of the arch made of 2.375″ metal pipes. The reality is the wind and sun seem to be keeping it clear. The center posts may be overkill but I like them their for the confidence factor.
End to End View Inside South Field Plateau Greenhouse
Ten days is long enough to let them settle into their new home so I now have some data from this morning’s observations:
They don’t seem to be avoiding or clustering around the east and west vents at the north end. In other words the vents weren’t a big positive or a negative to where the pigs chose to sleep. I had wondered if the vents would create drafts the pigs would not like but this doesn’t seem to be an issue.
The pigs were fairly evenly spread out. There was no piling and there was some empty space. They weren’t clustered in the middle or against walls. It is normal for pigs to lie right up next to each other. As a rule of thumb, they should not be piled more than about 1.25 pigs high on average. That would be a pig having it’s head on another. 2.0 high would be bad, that’s when pigs are sleeping on top of other pigs for warmth and can cause prolapsing and crushing. A little one on top of bigger pigs is not a problem, unless it falls down in the crack between larger ones and can’t get out. What I saw this morning was as stacking depth of about 1.0 which is great. This means the pigs were very comfortable with the temperatures.
I counted 77 pigs still laying down and snoozing in the north most 20′ of the greenhouse. Their total nest was about twice that – mostly vacated by the pigs that had already headed out to breakfast. That comes to 77 pigs / (38’x20′) or 9.8 sq-ft per pig for the area still occupied. This was a mix of sizes from 600 lb sows down to 50 lb grower pigs. I would estimate that they were using up around 50% of the floor area which left plenty of space for walking. Other pigs had been lying in that area before I arrived – Remember that most of the pigs had already left for the morning. But some of the bedding area clearly had not been laid on this past night so they were not using it all.
What makes this interesting is they have more room to spread out but that is the ‘stocking density’ they are choosing to use for their sleeping space. This is just sleeping nest space since they spend much time outdoors on the winter paddocks. If I assume that is their natural stocking level then they need about 9.8 sq-ft x 50% or about 5 sq-ft per pig. Do keep in mind that this is across many sizes of pigs and a rough figure but perhaps a good guide – I’m often asked by people how much space pigs need for shelter. Five square feet per pig is probably a good rule of thumb to what pigs think they need – I would allow a bit of extra space in building out.
Hot Wire Along Foundation Top to Keep Pigs Off the Tarp
Thus for a herd of 400 if all of them were in this space, which they’re not since we have other spaces, then they would need about 2,000 sq-ft of space for sleeping which is about half of the greenhouse’s 3,648 sq-ft. In reality, I would rather allow them to spread out a bit more than that and divide the greenhouse up into sections. Eventually each section will have its own entrance so the pigs will have a minimal walk to the outdoors and the larger world. The setup will allow auto-sorting by size using the creeps into the spaces.
Sidewall Snow Buildup & More Hot Wires
One of my concerns is how high the snow will build up along the sides of the greenhouse. This year is not a good test as we had already gotten most of our snow for the year by the time we got the tarp on. But we do have the east vs west sides to compare.
Sidewall Snow Buildup on East Side for Comparison
The top of the greenhouse foundation is nearly perfectly level but the ground slopes by about two feet from the north west corner down to the south east corner in order to provide drainage for the interior. There is also a berm around the uphill sides to prevent ground water from flowing into the bedding. The result is the east foundation is higher than the west foundation which does give a good comparison of what snow dump might be like.
One of the things we’re hoping to see is a reduction of our hay usage during the spring and fall mud seasons due to having more covered space. That extra hay is never ‘wasted’ as it goes to compost that feeds our soil. But it’s expensive compost. If we can cut the hay usage that goes to bedding that will help pay for the greenhouse. In a year or two we’ll know more how that pans out.
Thermometer measurements 4′ up at center of North End of Greenhouse
Update 20150306 of Greenhouse Data:
Outdoor = 15°F
Indoor = 45°F
Bedding = 75°F to 100°F
Search pattern for more on the Greenhouse Ark.
Outdoors: 34°F/10°F Mostly Sunny
Tiny Cottage: 64°F/61°F
Daily Spark: Mother Nature invented pork. Man improved it with salt, sugar and smoke to make bacon. Meat candy. -Adam & Eva Lution’s Smokehouse