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Calculation of Percent Oxygen after Vacuum Sealing a Container of Seed

By: Tim Motis

[EXCERPT] Postharvest seed loss due to insect damage is problematic for farmers as well as seed banks. One approach to control insects in a container of seeds is to lower oxygen levels using vacuum drawn with modified bicycle pumps, brake bleeder pumps, or other devices (see ECHO TN 93).

Air contains 21% oxygen by volume, meaning 100 liters of air is comprised of 21 liters of oxygen. Research has shown that insect mortality occurs when 5% (or less) of a container’s volume is occupied by oxygen (Njoroge et al., 2019). How do you know if your vacuum is strong enough to achieve such low levels of oxygen?

Part 1: Gathering required data

To calculate percent of container space occupied by oxygen, after removing some of the air by a vacuum-drawing device, we need to know a few things:

What crop are we dealing with? Let’s say we are storing maize.

What percentage of the container is occupied by seeds of that crop? Let’s say the container is 75% full of maize seed.

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