Tap I won't argue that it is a better option, but doing a rag test with 10 seeds is just assuming those 10 seeds represent the entire bag. Sure it will give you a guideline to follow, but how accurate is the guideline when you are using 10 seeds out of an entire bag? If you just guessed and added 15% per year old, I think it would be fairly close. Assuming the seed isn't moldy.
I am not sure if he is planting with a planter, or just broadcasting the seed and disc it in. If he isn't using a planter, I find it even less important to be precise.
But like you said, best option to test them, but it is still only a small sample of the seed in the bag. If I was still farming, and depended on the crop for income, I probably wouldn't use seed over a year old anyhow.
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