By Harry Brook
Rolling cropland makes a lot of good sense, especially if you have pulses to seed. It pushes the rocks down and smooths the fields making harvest easier, can limit dirt tag on pulses and can benefit silage harvesting, too! It prevents costly damage to the combine, if the crop lodges. However, a few basic rules need to be followed to make sure it’s beneficial, and not causing other problems.
Ideally, you’d like to do it just after seeding. However, rolling tends to pulverize the soil surface and make it susceptible to wind erosion. If you have fine-textured soils or low organic matter, rolling can cause crusting and prevent crops from emerging. If there is sufficient stubble present and the surface is dry, you can still roll right after seeding. A lot of people wait until after the crop is up. There are a few things to watch when rolling.
Firstly, the soil surface must be dry. If it is wet, mud will stick to the roller and you’ll end up pulling plants out of the ground. It is best to roll later in the day, hopefully on a sunny, warm day. That way the crop is slightly wilted and you won’t break the stems. Rolling in the morning when the stems are rigid and full of water will damage the growing points, if they are above ground.
Crop staging is important. The crop needs to be established so it can survive the rolling yet not so far advanced that rolling won’t permanently damage the head. For cereals, the crop should be at least at the 2 leaf stage and no more than 4 to 6 leaf stage. Too early and you kill off the seedlings. However, you also have to roll it before the growing point starts moving up the stem or you kill off the main stem of the plant. Under good moisture conditions this can stimulate increased secondary shoot production and possibly improve biomass yield, but it isn’t a guarantee.
Peas should be rolled at the 2 to 3 node stage, lentils, before the 7 node stage. Do not roll the crop if it is under stress. This can be from drought, heat, frost or a recent herbicide application. Minimize double rolling. Do not use any water ballast in the rolls, but roll when empty. Rocks will be pushed into the ground just as effectively with an empty roller as they will with a filled roller. If you roll when plants are damp, you risk crushing the growing point and possibly transmitting diseases around the field with the roller. Once rolled, leave the crop to recuperate for a few days prior to weed spraying or the multiple stresses to the plant may affect yield.
A good word of advice from Blair Roth, long-time Special Crops agrologist, regarding land rolling: “When it comes to rolling fields, make sure you are imposing no more than one stress on the pulse crop at any one time.” Rolling has a place for many farm operations, but it has to be done correctly to avoid costing you in yield.