RPSC Agriculture Research Officer (Agronomy) - 2022

• In fertilizer chemistry and soil fertility, potash is commercially expressed as potassium oxide (K2O), while plant uptake is evaluated as elemental potassium (K).
• The conversion is derived from molecular weights:
  • Atomic weight of K = 39.1 g/mol; Molecular weight of K2O = (2 x 39.1) + 16.0 = 94.2 g/mol.

• Conversion factor: % K = % K2O x (78.2 / 94.2) = % K2O x 0.83.
• Conversely, % K2O = % K x 1.20.

• For a fertilizer sample containing 1% K2O, the actual elemental K content is: 1 x 0.83 = 0.83%.
• Hence, the actual K content is 0.83% (Option 3).

By India Meteorological Department (IMD) standards, a rainy day receives >= 2.5 mm of rain, and a wet spell is defined as a consecutive period of more than two rainy days (> 2.5 mm per day).

• Continuous more than two days with rainfall of > 2.0 mm per day: Uses 2.0 mm threshold rather than the standard 2.5 mm criterion.
• Continuous more than five days with rainfall of > 2.0 mm per day: Incorrect days and threshold.
• Continuous more than two days with rainfall of > 2.5 mm per day: Standard meteorological definition of a wet spell based on the 2.5 mm rainy day threshold.
• Continuous more than five days with rainfall of > 2.5 mm per day: Represents an extended/persistent wet spell, not the baseline definition.

Diclofop-methyl (trade name Illoxan 28 EC) is a selective post-emergence graminicide recommended in wheat at the rate of 0.70 to 1.0 kg a.i./ha at 30-35 DAS for control of wild oat and canary grass.

• 0.5-0.6 kg/ha: Sub-lethal dose providing inadequate control of Phalaris minor.
• 0.7-1.0 kg/ha: Standard approved dosage of diclofop-methyl in wheat agronomy.
• 1-1.3 kg/ha: Excessive dosage causing crop phytotoxicity.
• 4-1.7 kg/ha: Far above safe threshold.

Duty of water represents the irrigating capacity of a unit volume of water throughout the base period to mature a crop (official key: Option 2).

• Delta of water: The total depth of water required by a crop during its entire period in the field.
• Duty of water: The relationship between the volume of water and the area of crop it matures; officially designated as the correct option by RPSC.
• Base of water: The time period (in days) from the first watering at sowing to the last watering before harvest.
• Water course: Small field channel carrying water from an outlet to the field.