Ameghino, Buenos Aires: Mechanical Efficiency in Harvest Combines

The industrial food system is based on mono-cropping on large plots of land in order to take advantage of the economies of scale that result from such a practice including the ability to mechanise your entire operation. Prior to my arrival in Argentina, my knowledge of the machines required to make seeding, maintaining and harvesting on such a large scale possible was very limited. Now I have a slightly better appreciation for the number of machines used to collect, store and transport the harvest most efficiently.

Earlier in the week, I had the chance to shadow a local agricultural engineer who works for a collective of local farms to ensure that their methods and technologies are up-to-date and functioning properly. Our goal was to visit two of the local farms to assess the quantity of soybeans lost from the combine being used to do the harvest.

To do this, we had a ¼ meter diameter mesh net. This net was thrown under the belly of the combine as it passed. Then, all of the beans on top of the net were counted to see how many seeds were going through the machine but then being discarded with the rest of the plant material, and we also counted all the seeds underneath the net to see how many were not being taken up by the machine at all.

At the first property, the combine was extremely efficient. About 7 seeds were being lost on top of the net and maybe 4 underneath the net. The net loss per hectare was minimal. I also had the opportunity to take a ride in this combine (because it has two seats) and was better able to appreciate how advanced and precise the harvesting technology is today. Inside the air conditioned unit, the collection rate, weight of harvest, and other valuable statistics are all documented on a digital screen. The machine is controlled by a steering wheel and a joy stick to for better precision.

At the second farm, the combine was much less efficient. At a maximum 85 beans were counted. The average of all the tests showed that approximately 400 kg of beans were being left behind in the field per hectare – which was about a 20% loss for this lot. Considering the loss for these machines should be closer to 2%, the loss was enormous. The agricultural technician shared that it isn’t entirely the machines fault since the soybean crop is particularly bad this year. Basically, because of the lack of rain, the plants have not reached their optimal height and consequently they are too short for the combine teeth to push them into the machine.

Two lessons have been learned – 1) machines can’t adjust for all crop failures, which may result in high losses and 2) it is extremely important to monitor the efficiencies of your machines and not just assume that there are meeting the projected efficiencies from manufacturer testing.