Question

what measures must be taken to prevent spoilage and insect attack of harvested grains

Answer 1

Here is your answer
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1.Expose the grains in sunlight so that they dry up and the moisture they have reduces.

2.Dried neem leaves can be added to prevent damage from pests.

3.Pesticides and insecticides be used.

4.Special chemical treatments can be done for preventing crops from damage.

Answer 2

heya
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These are the measures which must be taken to prevent spoilage and insect attack of harvested grains —

♦ The harvested grains are dried in sunlight to remove the moisture from the grains.

♦ Neem leaves are added with grains during storage to prevent insects from harming grains.

♦ The grains are treated with pesticides and fungicides.

♢ The latest method of storage is to release nitrogen in silos. When the amount of nitrogen will increase, the amoumt of oxygen will decrease. Thus, no insects or microbes can harm the grains.
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I hope it helps you !