The concept is good, and significant research dollars have gone into the development of auto-adjust combines, but set and forget can mean increased canola harvest losses. That is the finding of a research study conducted by the Prairie Agricultural Machinery Institute (PAMI) during harvest 2022.
“My thoughts on auto-adjust combines are that you have to measure the losses. They need to be calibrated with what is being displayed on the screen so that you actually know what losses you are incurring,” says Shawn Senko, a Canola Council of Canada (CCC) agronomist in Saskatoon, Sask.
Auto-adjust combines typically use sensors to monitor many parts of the grain threshing process. An operator sets the parameters for grain loss, foreign material and broken grain on the operating monitor, and then the combine automatically adjusts rotor/cylinder speed, fan speed, and concave, chaffer and sieve clearances. The trick, though, is that those numbers displayed on the screen can’t be trusted.
During the harvest of 2022, PAMI monitored 22 combines from Case IH, Claas, John Deere and New Holland for canola harvest seed losses. Eleven were equipped with auto-adjust and the other 11 were manually adjusted by the operator. Field testing was conducted between September 9 and October 10, 2022. One combine site was visited per day by PAMI technicians, and three timing samples were conducted throughout the day.
The objectives were to quantify the change in environmental conditions during a typical harvest day and the effect on combine losses of canola, and to measure the performance potential of combines with auto-adjusting settings.
Drop pans from Bushel Plus Ltd. were used to measure harvest losses and, while there are other loss pan manufacturers like ScherGain, PAMI decided to use only one brand to ensure consistency across combines. The drop pan is attached to the bottom of the combine and remotely released. The canola samples collected by the drop pan are cleaned and weighed, and the weight is entered into a loss equation to determine losses.
Weather conditions were taken from Environment Canada’s weather app and compared to an in-field, non-calibrated temperature and relative humidity meter.
The combine operators ran the combines as they normally would and used either auto-adjust or manually adjusted the combine. Eight of the combines were harvesting swathed canola and 14 were straight cutting canola. Yields ranged from 20 bushels per acre (1.4 MT/ha) to 65 bu./ac. (4.4 MT/ha).
The range of losses over the 22 combines was from 0.1 bu./ac. (6.7 kg/ha) up to 10.6 bu./ac. (712.9 kg/ha), representing 0.2 per cent to 29.4 per cent of total yield loss.
More variability with auto-adjusting combines
When comparing auto-adjusting and manually adjusted combines, there was no significant difference in the canola loss percentages. What did differ, though, was the variation in seed loss. The auto-adjusting combines had much greater variation in seed loss throughout the day than the combines that were manually adjusted. The researchers indicated that “while auto-adjusting capabilities may be able to adjust to changing conditions as well as manual adjusting types, they cannot be blindly relied upon – i.e. a ‘set it and forget it’ mindset should not be employed.”
“If you don’t measure it, whether you have an auto-adjusting combine or adjust manually, you won’t know what your actual losses really are,” says Senko.
The research also found that average daily temperatures impacted yield loss variation. As average daily temperatures increased, yield loss variation increased significantly. However, variation of temperature and relative humidity throughout the day did not impact loss variation.
Seed loss was not affected when harvesting swathed or straight-cut canola. There was also no difference in seed loss between the ground speeds tested.
Senko says that there is no magic number for harvest losses. Typically, a two per cent loss might be acceptable, but it depends on a number of factors. For example, he says that if a grower is pushing the harvest window towards the end of October, a three per cent loss might be acceptable.
“Two per cent is a nice number, but it is a trade off with harvest efficiencies,” says Senko. “When you look at the economics, going slower to reduce losses might provide overall higher yield, but if weather conditions delay harvesting and reduces the grade, you might be better off taking the loss and getting the canola off sooner. Knowing what that loss is and being able to make an informed decision is key.”
