From Dave Reay, University of Edinburgh
Having read your article about a smart sensor which can give crops just the
amount of water they need
(12 May, p 23),
I wondered whether this same approach could be applied to plant feeding.
Each of the three main nutrients required for plant growth—nitrogen,
phosphorus and potassium—can induce a specific change in leaf colour when
it is in short supply. Nitrogen deficiency tends to result in a yellowing of
leaves, low phosphorus turns them a purple/blue colour, and a shortage of
potassium makes their edges brown.
If a sensor could detect the nutrient needs of the plant by checking the
colour of its leaves, then it might be possible to avoid the overapplication of
fertiliser common to modern agriculture.
In the case of nitrogen-based fertilisers, such reductions are crucial, not
only in increasing the efficiency of crop production, but also in reducing the
amounts of nitrous oxide, a powerful greenhouse gas, produced by
agriculture.
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