Oilseed Rape Harvest: Combine Settings and Avoiding Losses

Why rape is the easiest crop to lose#

Rape combines three properties, none of which would be a problem alone. It flowers and ripens unevenly: by the time the top pods are splitting, the lower branches are still growing. The seed is very small — a thousand-seed weight of only 4–5 grams — so lost volume is invisible on the ground while weighing a great deal. And the pod opens under the slightest mechanical action: wind, a touch from the reel, vibration from the header. Together these produce typical losses of 5–20 %, and most of that happens not in the threshing drum but at the header. Which is why the work starts with setting the machine, not with picking a date. A useful benchmark: one lost seed per square centimetre corresponds to roughly 45 kg/ha — a quantity that looks like nothing at all on the stubble.

Combine settings: less is more#

Rape threshes more easily than any other field crop, and nearly every settings error is an excess. Drum speed comes down substantially relative to wheat: extra speed does not improve threshing, it cracks seed and produces oily fines that blind the sieves. Concave clearance goes up — the pod opens by itself and does not need to be rubbed apart. Fan blast comes down: rape seed is light and leaves with the chaff before any other material does, and this is where most of the in-machine loss happens. Sieves are set to smaller apertures than for cereals. Take the exact figures from your model's manual, because the spread between combines is wide. Check as you go: stop mid-pass, look in the grain tank for cracked seed and in the chaff for whole seed, and adjust one parameter at a time rather than several together.

The header matters more than the drum#

Most of the loss happens before the crop ever enters the machine. A table extension is needed: a standard grain header is too short, so pods strike the auger and open ahead of the knife. Vertical side knives separate interwoven stems, and without them the header drags whole patches along, shedding them as it goes. Lower and slow the reel — its job is to steady the crop, not to beat it. Set cutting height as high as the crop allows so that only the productive part is taken: surplus straw adds load and raises the moisture of the harvested mass. Match forward speed to crop density rather than to a wish to finish the field today. The best hours are morning and evening, when higher humidity makes the pods less brittle; in the midday heat header losses rise noticeably.

Timing: a narrow window set by moisture#

In Ukraine rape is harvested mostly in early July, but the decision belongs to the pods, not the calendar. The marker is seed moisture of 8–9 %: seed dark and hard, and a pod that snaps rather than bends when folded. Earlier means raised moisture and a drying charge; later means pods splitting at the first wind. The window is narrow, so harvest is planned ahead: machine ready, haulage arranged, store prepared. The measures that narrow the gap between top and bottom pods are desiccation and pod sealants; both require the label to be followed and both need checking against the terms of the contract for the lot.

After threshing: drying and storage#

Rape is very small and high in oil, so it behaves differently from grain in a heap. Clean green material out of the harvested mass immediately: weed and stem residue carries far more moisture and rapidly forms self-heating pockets. For long-term storage dry the seed to 7–8 % using gentle regimes — overheating spoils oil quality and raises the acid value. Because the seed is so small, the mass ventilates poorly, so check aeration at several points rather than trusting a single sensor. Monitor temperature through the depth every fortnight, and daily for the first few days after loading, since that is when residual moisture shows itself. Where a lot was assembled from fields harvested on different days, manage it as the wettest of them rather than as the average.