KEAM Agriculture: Agronomy, Soil and Plant Science
What this domain tests
The agriculture stream uses Physics, Chemistry and Biology and tests agronomy, soil science, plant physiology, genetics, entomology, plant pathology and agricultural economics. KEAM agriculture questions apply school-level science to field decisions: nutrient doses, seed rates, irrigation, pest thresholds and crop rotations.
Core rules and concepts
- Soil: pH affects nutrient availability; cation exchange capacity governs retention of K⁺, Ca²⁺ and Mg²⁺.
- Plant nutrition: N supports vegetative growth, P root development, K quality and stress tolerance; deficiency symptoms differ by mobility.
- Physiology: photosynthesis, transpiration, photoperiodism and seed dormancy explain yield and flowering.
- Genetics: pureline, pedigree and hybrid seed production; Mendel’s ratios predict segregating populations.
- Protection: integrated pest management combines cultural, biological and chemical methods; economic threshold level guides spraying.
Worked example
A recommendation is 120 kg N/ha. Urea is 46% N. Urea required = 120 ÷ 0.46 = 260.9 kg/ha. If a plot is 0.4 ha, the quantity is 260.9 × 0.4 = 104.4 kg urea. The reasoning is to convert the nutrient recommendation into fertilizer mass using the nutrient fraction; never treat 120 kg N as 120 kg urea. For split application, divide the final quantity, not the nutrient figure.
Traps that cost marks
Reading N, P₂O₅ and K₂O as elemental P and K; forgetting that urea is 46% N, not 100%; using gross plot area when a net planted area is specified; and confusing deficiency symptoms of mobile nutrients such as N with immobile nutrients such as Ca. Always carry units through the calculation.