Olsen method is used for phosphorus estimation in

🔑 Key Points
🌱 Phosphorus in plants:
→ Phosphorus (P) is needed by the plant to store energy, plant growth, and reproductive processes.
→ Phosphorus is not as naturally abundant in the soil as other macronutrients and is relatively immobile.
→ The amount of plant available P in the soil solution is related to soil pH.
→ Different Phosphorous extraction methods are used depending on the soil pH:
→ Bray P (acidic soils)
→ Mehlich-3 P (acidic soils)
→ Olsen P (neutral to alkaline soils)
→ The Olsen method is used to determine available phosphorus in mildly acidic, neutral, or alkaline soils.
→ This method has wide international acceptance as an indicator of soil P fertility.
→ The method is based on the extraction of phosphate from the soil by 0.5 N sodium bicarbonate solution adjusted to pH 8.5.