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• We constructed harmonisation functions for soil extractable P in arable lands. • Separate functions are provided for acidic and calcareous soils. • Models are constructed based on easily available soil properties. • Additional soil properties improve performance of harmonization functions in calcareous soils. Phosphorus (P) is a nutrient essential to living organisms and ecosystems. Accurate information regarding extractable soil P is necessary for agricultural management and environmental quality. Direct measurements of extractable soil P at large scales are usually impeded by considerable time, labour, and economic resources required for implementation. To meet agronomic and environmental monitoring needs, multiple extraction methods have been developed worldwide to estimate the different components of soil P. In France, three extraction methods are used, namely the Dyer method for acidic soils, Joret-Hébert for calcareous soils, and Olsen for all soils. Therefore, it is difficult to compare data obtained nationwide for monitoring purposes. Consequently, it is of significant importance to develop pedotransfer functions (PTFs) to harmonise extractable soil P data obtained from different extraction methods with the assistance of other easily available predictors from soil information systems. In this study, we used an extensive dataset from the French soil-monitoring programme for the calibration and evaluation of PTFs. We implemented the partial least squares regression to relate extractable P measured by the Dyer or Joret-Hébert method to extractable P determined by the Olsen method considering 14 soil properties (total P 2 O 5 , pH, cation exchange capacity (CEC), CaCO 3 , soil texture (clay, silt and sand contents), total organic carbon, and exchangeable Fe, Al, CaO, Mn, MgO, and K 2 O). We constructed patrimonial models by selecting the most important predictors. According to the results of 10 iterations cross-validation, the average R2, root mean-square error (RMSE), and mean error (ME) of the PTF of calcareous soils were 0.66, 25.81, and −0.11 mg kg−1, whereas those of acidic soils were 0.70, 24.02, and −0.87 mg kg1, respectively. The Joret-Hébert P 2 O 5 , silt, pH, total P 2 O 5 , CEC, and K were the most important predictors for estimating Olsen P 2 O 5 in calcareous soils, whereas Dyer P 2 O 5 , exchangeable Al, K, and pH were the most important predictors for estimating Olsen P 2 O 5 in acidic soils. We observed that the explanatory power of the soil properties was more important in calcareous than in acidic soils. As expected, the proxies of Olsen P 2 O 5 , namely, Dyer P 2 O 5 and Joret-Hébert P 2 O 5 , were the most important variables in modelling Olsen P 2 O 5 variations. In addition, the relationship between Olsen P 2 O 5 and Dyer P 2 O 5 was much stronger than that between Olsen P 2 O 5 and Joret-Hébert P 2 O 5. The results confirmed the feasibility of estimating extractable P in soil by PTFs that were constructed using statistical methods, such as partial least squares regression. The addition of more predictors that are related to agricultural practices and topography attributes may improve the prediction accuracy. [ABSTRACT FROM AUTHOR]