Agricultural Engineering, Farm Machinery and Post-Harvest Technology
Agricultural engineering, machinery, and post-harvest technology apply mechanical and processing principles. The exam tests implements, calibration, efficiency, and storage.
Farm machinery
Primary tillage cuts and inverts soil: MB plough and disc plough. Secondary tillage refines the seedbed: harrow, cultivator, rotavator. Seed drills place seed at uniform depth and spacing. Sprayers apply pesticides; calibration matches output to the label dose. Threshers separate grain from panicles; winnowers clean grain using air. Combine harvesters cut, thresh, and clean in one operation. Field efficiency = effective operating time ÷ total field time × 100.
Post-harvest technology
Post-harvest steps include cleaning, grading, drying, storage, milling, and value addition. Grain moisture must be low enough for safe storage; high moisture causes mould and insect damage. Storage structures should be dry, clean, and protected from rodents. Milling of paddy gives rice, bran, and husk. Moisture content can be expressed on wet or dry basis; state the basis.
Worked example
A machine works effectively for 6 hours in an 8-hour field day. Field efficiency = 6 ÷ 8 × 100 = 75%. If the theoretical field capacity is 0.5 ha/h, effective field capacity = 0.5 × 0.75 = 0.375 ha/h.
Traps that cost marks
Do not confuse threshing with winnowing. Do not mix wet-basis and dry-basis moisture. A disc plough is not a secondary tillage tool. Pure live seed accounts for purity and germination; do not use bulk seed weight blindly. High moisture storage is not safe.