Availability of Phosphorus to Wheat in Soils from North-West India as Related to their Phosphorus Adsorption Maxima

In a greenhouse experiment, with increase in P percentage saturation of adsorption maximum, dry-matter yield and total P removal by wheat increased in four soils representing different agro-climatic regions in north-west India. The adsorption maxima values for soils were 9.50, 4.01, 1.25 and 1.19 mg/g for Hapludolls, Ustochrepts, Haplhumults and Haplustalfs, respectively. For obtaining maximum yield or total P removal, the soil having high P adsorption maximum value required low percentage saturation of adsorption maximum and vice-versa and these levels were 0.78% for Hapludolls, 2.5% for Ustochrepts and above 5% for Haplustalfs or Haplhumults.