Greenhouse Ventilation in part

Farming is a lot of hard work.  The results are borne by the effort put into farming.  For many areas in Canada and certainly in Northwestern Ontario, the weather does not give the growing results needed.  To solve that problem, an investment often looked into is a greenhouse.  Since a greenhouse can take many forms, one needs to know what type of structure to get into. A cold frame is a good way to start or even an open ended shelter allows you more growing opportunity.  Perhaps a double poly greenhouse with an air buffer between the poly layers, a hothouse, or even a year-round greenhouse would be the ticket.

No matter what type is used, the advantage is to gain a bit more heat by trapping it in the structure.  The disadvantage is the necessary requirement to control the air temperature from getting too hot.  There are several ways to accomplish cooling on hot, sunny days.  Doors and windows on smaller greenhouses will often allow a breeze to cool it down.  Larger greenhouses including some commercial models have roll-up side panels that keep the lower zone of the greenhouse cooler.  Yet another method is to use fans and vents, forcibly exchanging the air in the greenhouse.

Our greenhouse has all three of the aforementioned methods available for cooling.  Depending on the weather, we can chose the method that works best.  When the weather is hot and sunny and there is no breeze, the fan and vent method is the only way to keep it cooler in the greenhouse.  Over the last few weeks, we have been designing a more efficient fan and vent control system.  Our greenhouse has two 42" cabinet fans that can be run at low or high speed.  We also have two powered vents at the opposite end of the greenhouse.  Typically, the fans would start together, the vents would open, and the greenhouse would start to cool.  On days where the weather is cool but the sun is hot, full fan and vent is not required, but rather maybe one fan running slowly would be enough.  An average day with sun and cloud can become problematic, too.  Full speed fan operation might create too much change too quickly.  So now for the technical side of things!

The decision to design the new control system comes from the desire to keep the plants in the greenhouse from being shocked by a sudden or rapid temperature change.  The engineering behind the function is to run the fan and vent system in four logical steps.  When the temperature gets too warm in the greenhouse, one vent opens and one fan on low speed starts up.  If that doesn't satisfy the control parameters, the second fan starts on low speed with the second vent opening.  Should the parameters still not be met, one of the fans goes to high speed and finally the second fan would go to high speed if required.  Essentially, this is a cascade control for ventilation.

In the construction of the system controls, each stage is operated by individual temperature sensors and adjustable controls.  This will allow for customizing the ventilation where one side of the greenhouse might get hot more quickly than the other side, or on the cool down, one side cools before the other.  A combination of NTC sensors and bimetallic sensors should allow for a smooth operation.  Sensor locations can be adjusted to meet the canopy level of the plants and are generally placed mid-greenhouse to minimize airflow disturbances.  Further to that, the NTC sensors are placed inside perforated pipe (Buffer Tubes) to keep the temperature sensing from becoming erratic.  Most of the equipment used we have been able to recycle, reuse or at least, use part of.  Two of the controllers we are using are new and extremely accurate.  Items like the controller enclosure were salvaged from an industrial site demolition.  Finally, we have independent wireless temperature/humidity sensors that we can monitor via a smart phone app to keep a watchful eye on the system.  Below are some photos of the ventilation equipment.

Hopefully you can make sense of what I am writing about in this blog update from the farm.  If you want to check it out in person, a tour would definitely be in order!

Control Box Wiring

Control Box Front Panel

Power Operated Vents

Sensor/Buffer Tube

SW Cabinet Fan

NW Cabinet Fan and Control Box

Soil. What about it?

Recently, I have found an interest in the area of deglaciation. That is to say, the mystery of what happened here thousands of years ago gave shape to what can be seen here today. Our farm sits on mostly clay/silt, but has a few bands of sand here and there as well as some random rocks thrown in where you least expect them. Those rocks have often been unearthed with the tractor and plow, though one was found with a new set of blades on our riding mower. Ooops. 

What can be seen specifically in our yard is banding of different soil types as it settled, presumably after being washed out of the retreating Laurentide Glacier and then being settled by the ancient glacial Lake Agassiz. It is hard to picture in your mind as you stand in the yard, a wall of ice, melting and crumbling away, perhaps hundreds of feet high where your house now sits. The random rocks would have been bulldozed by the glacier off the higher rocky prominences in the area, only to fall off the edge of the glacier as it melted in later times. Speculation, it may be, but we do have glaciers today that have shown us how they behave. It can make a person feel pretty small in the world, but maybe moreso blessed to be witness to the evidence! 

 Our farmyard is a soil called Orthic Gray Luvisol, for the most part.  I know the Poplar trees like it and thrive in this soil, as do the Moose Maple and Balsam trees. That being said, it grows a good crop of beans and with a bit of biomass such as the rotted overburden of needles, leaves and such, potatoes love the soil as well as much of our selected crops. Then there is this very interesting but oh, so stubborn hard-pan layer that sits below the top level of soil. It is made of calcium carbonate - the same stuff that makes well water hard. It prevents rain water from going deep into the soil and gives our farm a problem with rainfall runoff. So last year we purchased a big, chisel like device for the tractor called a middle-buster. It can penetrate the hard pan with a bit of effort, giving much needed drainage and also causes some of the calcium carbonate to return to the growing soil which is of benefit to the crops. 

Apart from the farm, the Dryden area can reveal the glacial evidence in other ways. There are very cool features on the shores of Wabigoon lake called "varves" in the clay banks. Basically the layers that were built up over the centuries of glacial melt. You can also find moraines (large gravel features that run for many kilometers at a time) as well as eskers which make some beautiful sandy/gravelly "varves" as well. This photo was taken East of the farm, in a gravel pit. The layers are incredible!

Also, a little closer to home is this massive boulder, all by itself amongst much smaller clast (broken rocks) on a clay hillside. It is quite amazing, being that it is approximately 20 feet by 16 feet wide and 8 to 10 feet high!  Just think, the glacier carried it to that spot!

Enjoy your time outside and keep your eyes open! You never know what interesting thing you might find!

Additional Land Cleared

 With apologies, this blog has been unreasonably inactive for 2 years.

Farming takes alot of time and blogging was something that got neglected for the media presence of our farm.  It was easier to satisfy the masses on our other SMPs, those being Instagram and Facebook, so you could go there to get a snippet of the farm activities.

But today I will provide a quick overview of the post-market activities on the farm, that made for a busy September and October.  We cleared land.  More land.  Scrubby and mostly unused land.  Land that makes a person growl as they walk in it because the scrub and Moose Maple makes for unpleasant movement within. Largely unforested, there were a few Poplar trees, some ratty Balsam trees and two beautiful White Spruce trees.  I saved the White Spruce and landscaped around them to create an island in the middle of the working field area.  It will be a bit inconvenient when using equipment but the aesthetic of it will be of much greater value!

Most of the scrub, stumps and weeds were moved, sifted and set to be burned off to the side.  Piles of soil that were previously placed in this area were spread out over the opened ground.  Any remaining sticks were hand picked and added to the burn piles and the piles were lit off.  Remaining ash and soil was pushed back onto the open ground, then I brought in the 2-bottom plow and turned the opening over to allow winter's cold to break down the soil in a way only nature can.

Tree Island at Right

Plowing Complete

Tractors and Plow

This clearing operation gave an extra 3/8 of an acre to the total field size and eliminated some unmanaged piles of dirt as well as becoming one open area with ease of management for the future of the farm.  For the coming 2023 farm season, this new area should be full of Sweet Corn, Squash and Black Oil Sunflowers.  I am anxious to get back to the soil!