Determination of Critical Level of Available Soil Phosphorus for Maize

This study includes 20 soils (from Ludhiana district) which varied from low to high in available P. In low P soils (5 mg kg⁻¹ soil Olsen's P), significant increase in dry matter yield and total P uptake due to fertilizer application was observed up to 40 mg kg⁻¹ P₂O₅ level, whereas in medium and high P soils no significant response was observed. Dry matter yield and Bray's per cent dry matter yield indicate significant positive relationship with Olsen's extractable P and AB-DTPA extractable P. The criticalsoilfertility limit of available P for maize was found to be 85 to 8.0 mg kg⁻¹l soil for Olsen's extractant and AB-DTPA extractant, respectively.