Canola produces a lot of fine material as chaff, which must be spread a long way from the combine's centre line to prevent obvious rows in the next crop. Heavy mats of canola residue will crust and push ahead of ground openers, resulting in plugging. Heavy harrow Pea stubble is the most difficult residue to handle. All the vines must first be picked up by the cutter bar and then completely chopped and spread. Long vines are almost impossible to plant through, and harrows usually just bunch the pea stubble into piles.
Cereals are relatively easy to chop and spread.
Special attention is needed when the straw is tough or damp and in low or lodged areas when the straw is green. Many knowledgeable farmers routinely harrow cereal stubble soon after combining to improve the spread of straw. A lodged crop or stubble that is lying on the ground, as is often the case with peas, can be a problem. The addition of pick-up fingers on the windrower or straight header, dropping the header height and slowing downhill help to ensure that these conditions won't hinder the planter next spring. Tall standing stubble reduces erosion risk and increases snow trapping but may cause plugging during planting.