Agronomy Library > Soil Conservation

The Heavy Harrow: is it a useful implement?
Author: Nick Underwood
Date Created: June 25, 2003
Last Reviewed: February 21, 2007

Or is it an expensive piece of equipment that does not pay for itself? In these days of continual cost cutting the heavy harrow is the subject of discussion with strong feelings being displayed, both for and against its use. In the Peace region and, I suspect, in many other parts of Alberta, farmers continue to ask if it is worthwhile to heavy harrow. I have seen some cost figures attributed to the task, which are questionable. In this article I don't wish to get into detail about the cost, but I will say that I believe the operation can be done for less than $3.00 per acre. At that cost a 70' heavy harrow with tractor to pull it at 10 m.p.h. is earning/costing $240.00 per hour.

So what is the benefit of heavy harrowing? The Central Peace Conservation Society (CPCS) agronomist (Gary Ropchan) started doing trials in 2001 "to evaluate the benefits from using a heavy harrow in a zero till seeding system". In 2001 the trial was done on canola. In 2002 the trial was done on barley, peas, canola and wheat. Findings so far show an economic disadvantage to using the heavy harrow. This appears to be for two reasons; first the cost of the heavy harrowing, and second the fact that heavy harrowing did not have a positive effect on yield. CPCS is continuing the trials in 2003.

Should we expect a yield increase from heavy harrowing? Are there other reasons for doing the job? To find out, I talked to three farmers in the Peace to find out if they use a heavy harrow, and why. Together they farm almost 10,000 acres with at least 100 kilometres distance between them. Their soils vary. None of these direct seeders identified an expected yield increase as the reason that they used a heavy harrow. However they all feel that the operation helped to provide the seeding conditions that they want. This implies that there is an expected yield benefit.

In the Fairview area our farmer likes to spread the straw in the spring to stop it sticking to the mud. In wheat stubble that received pre-harvest glyphosate, heavy harrowing is helpful to the seeding operation because it eliminates sprayer tracks that can cause plugging. The harrowing makes the land more ready for the seeder. In heavy canola crops that leave lots of chaff, heavy harrowing after harvest spreads that chaff more evenly than the chaff spreader on the combine. After seeding (with a 3" stealth opener) he has tried heavy harrowing to get an even mat of straw, that helps to prevent drying in the seed row. He feels that helped this year anyway. In the Debolt area our farmer feels that is very important to have a mellow layer of mulch on the surface at seeding. He applies NH3 in the fall with ¾" knives on a 12" spacing in a different direction to the planned seeding. In the spring he heavy harrows and then seeds. In the Hythe and Wembley areas our third farmer also likes to see loose mulch on the surface to help 'seal it up' to reduce moisture loss. He also bands NH3 in the fall. He farms a wide variety of soils and feels that some might not benefit from the operation. Heavy harrowing is a spring job for him and a very important reason doing it is to level out tracks from the previous year's spraying and harvesting operations. These tracks can cause seed to be left stranded on the surface or at the wrong depth. They also make the seeding operation more stressful.

What CPCS is attempting to find out, whether or not there are financial benefits to heavy harrowing, maybe a mute point? As an owner of a heavy harrow myself I find that it has its uses and has got me out of a jam, at low cost, several times. Having a level seedbed to seed into is very important. It may be difficult to prove that a level field is going to yield higher than a rough field. I sure know which one I would rather harvest!