Technical Knowledge: Agricultural Produce, Storage and Warehousing Science
This domain covers agricultural produce, storage and warehousing science: post-harvest handling, safe moisture, storage structures, insect and rodent control, quality assessment, and warehouse operations. Questions test whether you can protect grain from deterioration.
Core rules
- Safe storage moisture (approximate, commonly cited): wheat 12%, paddy 14%, maize 12-13%, pulses 9-10%, oilseeds 7-8%. Above these, mould and heating risk rises.
- Cool, dry, dark, ventilated storage slows insects and fungi; aeration equalises temperature and prevents moisture migration.
- Bag storage uses dunnage, stack limits, gangways and first-in-first-out rotation; bulk storage uses silos with aeration and temperature cables.
- Fumigation with phosphine from aluminium phosphide tablets needs an airtight enclosure, suitable temperature (above about 15 degrees C) and the full exposure period. Leaky godowns waste gas and fail.
- Khapra beetle, grain weevil, flour beetle and pulse beetle are key storage pests; rat proofing, baits and burrow treatment control rodents.
- Quality checks: moisture meter, foreign matter, broken grains, weevils, and aflatoxin in maize and groundnut.
- WDRA-backed negotiable warehouse receipts let farmers pledge produce for credit.
Worked example
A wheat lot arrives at 15% moisture. Reasoning: 15% is above the 12% safe limit, so direct bag storage would cause heating, mould and insect build-up. Dry to about 12% or below, cool, then stack with dunnage and monitor. Fumigation is not a substitute for drying.
Traps
Confusing paddy with milled rice moisture; fumigating a leaky shed; storing oilseeds at cereal moisture; mixing old and new stock; and treating a bad smell as normal when it signals heating.