Harvest loss goals as grain percentage
By Marcel Kringe and Peter Newman
The American Society of Agricultural and Biological Engineers (ASABE) recommend that machine harvest losses (from the rear of the harvester) should be 1% of grain yield or less for all grains. However, experience by grain growers, ag engineers and proponents of grain loss measuring equipment have found some exceptions to this rule. The target of <1% losses is a good rule of thumb but some of the exceptions include:
Table 1: Achievable grain loss targets for selected crop types.
|Real life conditions
|Canola and small grain
|Grain loss of in excess of 10% has been measured in the field by growers. Growers were unaware they were losing this much until they measured with a drop tray.
|In good harvest conditions - <0.5% loss is achievable.
|In pulse crops, header front loss is responsible for most grain loss and as such is the primary concern for growers.
NB: Targets are for harvester machine loss only, does not include header front losses.
Target grain losses stated in Table 1 are achievable goals, but growers also need to consider the cost of compromises to harvest capacity, and accept the balance between the cost of harvest loss/ha and the cost of harvest capacity (ha/hr or T/ha), because crawling/harvesting slowly to achieve 0% harvest loss decreases efficiency.
We need to keep in mind the simple equation of:
Total cost of harvest = cost of harvest (harvester + chaser bin) + harvest losses.
It is necessary to determine the trade-offs between harvest loss and harvest efficiency for your operation - What numbers can I tolerate and what am I willing to gain or give up?
A harvester plus chaser bin may cost $500 to $800/hour to operate including cost of ownership (depreciation + interest), fuel, repairs and maintenance, and labour. For example, if a harvester covering 10ha/hour must slow down by 10% to reduce harvest losses this will increase the cost of harvest by $5 to $8/hectare. This extra cost must be compared to the savings in reduced harvest loss to determine what is optimum.
Is the only answer to slow down?
Slowing the harvest speed down is not the only answer and should not be the first thing we try to minimise harvest losses. Slowing down should be the last resort. Our goal should always be to maintain harvest capacity while minimising losses. Drop pans provide a repeatable and accurate methodology to measure losses, allowing the opportunity and freedom to change/try settings and learn new settings/techniques, and measure the impact of each adjustment.
Measure your harvest losses with a drop pans change one thing then measure again. Repeat this process until you achieve acceptable grain losses below 1% of crop yield, while achieving good harvest capacity.
Table 2: Factors affecting harvest losses and ability to influence.
|What we cannot influence
|What we can influence
|Early and late morning dews
|Combine capacity (per machine or more machines per farm)
|Variety differences (hard to thresh, pod-shatter canola and pulses)
|Combine set ups (concaves, sieves, header fronts)
|Pre harvest machine check lists: calibrate sieves, concaves, internal set ups, header front set up (angles, guards)
|Small grain/kernel sizes due to drought or disease conditions
|Maintenance on parts which wear, to maintain fuel efficiency and performance optimisation
|Impact of biotic and abiotic stresses that result in uneven crop yields/volumes at harvest
|Consistent harvest loss checks with drop pans (preferrably remote controlled system for safety)
|Field sizes (logistical consideration to keep combine full of material)
|Consistent calibration of harvest loss sensors with drop pans, calibrating of harvest automation systems
|Driver (harvest team) knowledge and awareness
|After market solutions for header front and combine set ups
|Harvester clinics and dealer support
|General settings changes
|Mind-set changes to implement different ways of combine set ups and proactive approach to harvest
|Pre-harvest management of the crops (desiccation/swathing for weed infested fields or uneven crops for dry down)
Share ideas and questions to manage harvest loss on Twitter using the hashtag #harvestloss.
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