ICAR AIEEA PG Agronomy 14 July 2023 (Shift 1) Paper

Calculation of crop Water Use Efficiency (WUE):

• Formula: $\text{WUE} = \frac{\text{Economic Yield (kg/ha)}}{\text{Consumptive Water Use (mm)}}$
• Yield: $4.0\text{ t/ha} = 4,000\text{ kg/ha}$
• Water used: $40\text{ cm} = 400\text{ mm}$
• $\text{WUE} = \frac{4,000\text{ kg/ha}}{400\text{ mm}} = 10\text{ kg/ha/mm}$.

HCN (prussic acid / dhurrin) toxicity in sorghum:

• Young sorghum plants synthesize the cyanogenic glucoside dhurrin, which hydrolyzes into free hydrocyanic acid (HCN) in the rumen.
• The universally recognized critical toxicity threshold is $200\text{ ppm}$ ($200\text{ mg/kg}$ dry weight or $50\text{ mg/kg}$ fresh weight). Fodder containing $\gt 200\text{ ppm}$ HCN is lethal to cattle and buffaloes.

Meteorological definition of a rainy day in India:

• The India Meteorological Department (IMD) defines a 'rainy day' as a day on which a meteorological station records rainfall of at least $2.5\text{ mm}$ ($0.25\text{ cm}$) or more in a 24-hour cycle.
• An agricultural rainy day is defined as rainfall $\gt 5.0\text{ mm}$ in 24 hours.

Calculation of urea fertilizer requirement:

• Fertilizer Grade: Commercial urea contains $46\%\text{ N}$.
• Formula: $\text{Urea required} = \frac{\text{Target N dose}}{\%\text{ N in fertilizer}} \times 100$
• $\text{Urea} = \frac{100\text{ kg}}{46} \times 100 = 217.39\text{ kg} \approx 217\text{ kg}$.