There has been a lot of interest in the heavy harrow the last few years and many farmers feel they are a necessity before they get into direct seeding. The main purpose of the harrow is to spread crop residue. If you have your combine set up with a good straw and chaff spreading system you may not need to harrow your fields. The heavy harrow, like all harrows, will not spread chaff. This must be done with the combine. If you need to spread the straw with a harrow, do it as soon as possible after combining on a hot fall day. The heavy harrow will spread the straw better than a conventional harrow, but you must ensure that it is set properly for your field conditions.
Dr. Bill Hamman, Research Manager at the Monsanto Farm at Lethbridge, says "The heavy harrow works well for managing residue and works well for shallow incorporation of Avadex, but both can not be done at once." When spreading straw the angle of the harrow should be set to allow the harrows to fill but clean evenly to avoid bunching. When incorporating Avadex or fortress they should be set fairly straight. When harrowing pulse stubble it can roll into large bunches under certain conditions. "If not used properly they (heavy harrows) can problems." Said Hamman.
If you were in an area with hail this year that flattened much of the crop, or there were other reasons the crop was unharvestable, then harrowing would be required. With the use of a heavy harrow "you can direct seed a field that you may not be able to otherwise," says Hamman.
Harrowing will also stimulate weed growth, that will be killed with a frost in the fall or can be controlled with a pre-seeding burnoff in the spring. The heavy harrow is not necessary for this as any harrow will do, including diamond, rotary, tine or oscillating harrow. If you are unable to seed low residue fields, canola, peas, lentils, etc., early, a spring harrowing may help to create a dust mulch on the surface to avoid excess moisture loss. Once again any harrow will do this and a heavy harrow is not required.
Terry Pearse has been direct seeding in the Tisdale area for many years. He uses the oscillating harrow in his direct seeding system. "There are four reasons I use the harrow: 1) I can start with a smooth field the next year, not only remove drill runs but also any mole hills that have sprung up over the summer. 2) It helps germinate any weeds and volunteer grain in the fall. 3) I get enough soil disturbance to allow a little black soil showing through to help warm the soil next spring. 4) An early spring harrowing on low residue fields will give me a dust mulch to help prevent moisture loss," Pearse explains.
The heavy harrow has some advantages over the other harrows. It has variable tooth angle and variable down pressure, so it can harrow very aggressively. Do not aggressively harrow on low residue fields or light soil in the fall since the soil on these fields may blow all winter long if there is not adequate snow cover. "Management is the key. Every field has a different condition to deal with" says Pearse.
Tips on using the heavy harrow by Monsanto
Trash Management
Avadex BW & Fortress incorporation
The heavy harrows on the market today do a good job of what they are intended to do. There are many direct seeders who do not own a heavy harrow and have been doing a successful job of it for many years. If you have a good straw and chaff spreading system and a seeding system that gives you very little plugging problems the heavy harrow is not necessary, except for those special problems like lodged crop. Harrowing a field in the fall or early spring is one of individual requirements depending on field conditions. There is no use burning fuel, harrowing a field that does not require it.
Look at the heavy harrow as another tool to use in your operation, it is not required by all, but it may fit into your plans.