Relationship between phosphorus sorption indexes and plant response in a greenhouse experiment

Twenty six phosphorus (P) sorption indexes were utilized as complement measurements of P fertility diagnosis on sixteen soils from Sandy Pampa and Ondulating Pampa. Adsorption values behaved as non‐availability indexes and were negatively correlated with P absorption by plants. The best parameters were P‐25–2hrs: adsorbed P with 25 μg P added, equilibrium period: 2 hrs (r = ‐0.89**); BC: buffer capacity (r = 0.86**); P‐1550: adsorbed P with 1550 (μg P added (r = ‐0.80* in Ondulating Pampa). Intensity or desorption related positively with plant P (r = 0.69**). When applying P fertilization in a greenhouse trial, absorbed P, dry matter, and foliar area showed a positive correlation with adsorption indexes and a negative one with desorption indexes.