In a group of 24 related calcareous soils, derived from Jurassic oolitic limestone, there was marked variability (13‐fold) in phosphate buffering when expressed as the maximum buffer capacity. This variability was most closely related to the iron content and pH of the soils, and these together accounted for 72% of the variance. This percentage was not increased by including CaC03content or organic matter, which were also correlated with the maximum buffer capacity. A high correlation with specific surface area of CaCO3was probably an indirect effect due to the high correlation between this variable and the Fe and pH of the soils.