St. Clements, Man. – The prospect of an environmentally friendly biomass tree farm that annually returns $60 to $80 per acre holds a certain attraction, especially considering that each planting is good for 15 to 20 years.
However, the equipment is highly specialized and not easily available. In fact, when it comes to harvest, the equipment doesn’t even exist.
Farmers considering planting trees into an unproductive field may want to think again. That’s the advice of Pete and Irene de Graaf, owners of a 100 acre poplar and willow biomass plantation at St. Clements Man.
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“People think they’ll put a tree plantation on marginal land,” says Irene.
“But you know what? If the land won’t grow a good wheat or canola crop, it won’t grow a good tree crop either. Consider your best land, not your worst land.”
She adds that trees require better pre-plant weed control than conventional field crops, and when the land develops into tree fields, it needs the same degree of care as a shelterbelt strip.
Weeds and trees don’t mix, according to the de Graafs. Their experimental biomass tree farm is heading into its fourth year of growth and they’re not happy with their weed control program.
“We knew weed control would be difficult,” says Pete. “You have to start with totally weed-free land because you can’t use chemicals so close to the young trees. When the trees are small, the slightest exposure to chemicals kills them. Once they start growing, they have branches right down at ground level, so once again chemical control can’t be used.”
He says cultivation works, but because poplar roots run laterally out from the tree and remain close to the soil surface, depth control is essential to avoid cutting the roots.
As the trees mature, the area becomes too dense to reach with a tractor, he says.
Tractor damage to the lower branches is also a concern. To push the branches up and away from tires and fenders, Pete made a pipe framework that lifts branches and guides them over the top of tires.
Forestry experts told the de Graafs to accept the weeds and be patient until the trees outgrow them. After all, weeds exist in nature, out in the forests. Irene maintains that the de Graaf farm is an agroforestry operation, not a piece of bush.
“The agro part of that term means agriculture. We’re farmers. We won’t tolerate weeds sucking up moisture and nutrients from the soil.
“The cultivator always leaves a one foot square patch around the base of each tree. You can’t help it. If there’s a thistle or a little bunch of wild oats in that square, it turns into a half million new weeds next year. So we feel we have to get rid of every weed we possibly can.”
The de Graafs hire people each summer to hoe around the trees. Irene grew up on a vegetable farm and knows first-hand that hoeing around delicate plants is no fun. She says it’s not easy finding people to do this work.
Roundup Ready
“Nobody wants to hear the words Roundup ready poplar trees,” says Irene, adding that researchers are already working on them.
“The idea of a fast growing tree like a poplar that’s also resistant to Roundup makes a lot of people nervous, including us.”
Pete shares her reluctance, but points out the other side to the issue – soil erosion from wind and water.
To properly control weeds before planting, the land should be in summerfallow for two or three years.
“There’s no soil protection during that time. And once you get the trees in the ground, you still need to cultivate for another two or three years to keep the weeds down.
“For five or six years, all you have is bare land with a few little pencils sticking up – a perfect setting for erosion. That’s why there may be some logical benefit to something like a Roundup Ready poplar tree.”
He says that areas where the trees got a good start and where they hand-hoed, the trees are now big enough to shade out the weeds. Weed populations in those areas of the field started diminishing in 2007. In other areas, weeds and trees are still battling.
Pete says countless hours on tractors have given him time to think about a better weed control plan.
“First, if you look at our net energy expended on this project, I question if we consume more energy cultivating this plantation than it will ever produce in biofuel. If we factor in all the petroleum fuel I’ve put into the tractor, maybe my new plan is better for the environment.
“It works like this. If I cut down one tree each time I reach row end, then my rows get progressively shorter every time I cultivate. That’s the tree that theoretically would have gone into the gas tank on my tractor as biofuel.
“After a while, I’ll reach an equilibrium. I’ll have a balance where I no longer need to put fuel in my tractor because I’ll have no trees left to cut down at the ends of the rows. No further need to cultivate or waste fuel.”
While Pete admits his tree removal plan may seem silly, it underscores the fact that they have already paid out a significant sum of money for fuel and hand hoeing. These costs must be factored into the long-term financial analysis of a tree farm.
A more practical alternative to cultivation and hoeing was presented at a Forest 2020 field day at Hillside, Man., last fall.
The new Enviromist Spraydome plot sprayer imported from England is engineered to allow chemical application without risk to the trees.
The Spraydome hood conceals two nozzles and is surrounded by a fringed skirt dragging down to the soil. This skirt allows the operator to spray up to the tree trunk without spraying chemical on the tree.
Although the Spraydome should simplify in-field weed control, it is not a substitute for a clean field before planting. Plus, the tree stand will eventually become too dense to drive machinery between the rows.
Once the field is weed-free, trees are either machine-planted or manually planted with the time-honoured tree planter’s spade.
Irene says they opted for the human method because they wanted to create local employment.
Covering their 100 acre field with trees required 20 people at $10 per hour for 10 days. Irene says the grid accuracy of their hand planted trees gave them straight rows, which were easily cultivated for the first three years.
A tree planting machine demonstrated at Hillside is a commercially available unit similar to those used by vegetable growers, Christmas tree farms and custom tree planting contractors.
Manufactured by the Mechanical Transplanter Company in Michigan, the unit mounts on a three-point hitch. It slices a groove for the sticks, pops the stick into the soil at the correct spot, brings the soil back around the stick and packs it with the steel packing wheel.
The depth and spacing between plants is easily adjusted. The transplanter can be fitted with a liquid drum to automatically squirt a water-fertilizer solution down to each new tree.
Although the unit is called a mechanical transplanter, it relies on human input.
The tractor operator must drive perfectly straight rows. All three seated planters must be diligent working with bare rootstock because it’s often difficult to see which end of the stick should go into the ground.
Mechanical transplanters of this type have been in production in North America since the 1950s.
Used transplanters often sell for approximately $2,000.
