Does this moisture meter work?

It is procurement season. Almost all places in the country have had a tumultuous encounter with the monsoon. And given the way millet crops survive nature’s vagaries a fair number of millet farmers have been able to bring their produce to the markets. And this is one of the primary point in the supply chain where a millet farmer suffers a blow to his/her expectations. And the stick wielded in most cases is a moisture meter.

For safe storage, the moisture content should be less than 12%. More than that and the possibilities of pest and fungal attacks increase dramatically. But as a grain dries its weight goes down. And a producer would like to sell their grain before its weight reduces too much. So there is a competing interest between the seller and buyer and this the moisture meter takes on a larger than life role.

When using moisture meters with millets (or other not so common grains) I would advise some caution

  1. Do check if the moisture meter has a certificate of calibration for the millet grain whose moisture is being measured.
  2. Irrespective of whether it is certified for the millet grain or not, it is good to do a comparative test –
    1. take a sample of a ‘mainstream’ grain for which the calibration curve has been published for the particular instrument
    2. measure the moisture of a few millet grain samples and of the ‘mainstream’ grain samples.
    3. put a good 2 or 3 kgs of both grains out to dry for at least 2 hours
    4. draw samples and measure the moistures again.
    5. find the moisture loss rates for the two grains.

Given grains of two different sizes and comparable moisture levels –¬†all other factors kept the same – the smaller grains would dry slower than the larger grains. So the moisture loss rate calculated from the above experiment should be proportional to the size of the grain – if it is the same for both grains or widely off, the calibration for either, or both, of the grains is off and the moisture meter is not a good indicator. Now the sad reality is that most farmers are in no position to do the test detailed above. And no dealer would entertain any such interference in their business.

This is where farmer producer organizations (groups/cooperatives/companies) can play a role by emphasizing on the use of fair and appropriate measures. And individuals and organizations working with such FPOs will, I hope, promote better informed methods, leading to a better deal for both the seller and the buyer.


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