Pedotransfer functions for isoproturon sorption on soils and vadose zone materials
2011
Moeys, Julien | Bergheaud, Valérie | Coquet, Yves
BACKGROUND: Sorption coefficients (the linear KD or the non‐linear KF and NF) are critical parameters in models of pesticide transport to groundwater or surface water. In this work, a dataset of isoproturon sorption coefficients and corresponding soil properties (264 KD and 55 KF) was compiled, and pedotransfer functions were built for predicting isoproturon sorption in soils and vadose zone materials. These were benchmarked against various other prediction methods. RESULTS: The results show that the organic carbon content (OC) and pH are the two main soil properties influencing isoproturon KD. The pedotransfer function is KD = 1.7822 + 0.0162 OC1.5 − 0.1958 pH (KD in L kg−1 and OC in g kg−1). For low‐OC soils (OC < 6.15 g kg−1), clay and pH are most influential. The pedotransfer function is then KD = 0.9980 + 0.0002 clay − 0.0990 pH (clay in g kg−1). Benchmarking KD estimations showed that functions calibrated on more specific subsets of the data perform better on these subsets than functions calibrated on larger subsets. CONCLUSION: Predicting isoproturon sorption in soils in unsampled locations should rely, whenever possible, and by order of preference, on (a) site‐ or soil‐specific pedotransfer functions, (b) pedotransfer functions calibrated on a large dataset, (c) KOC values calculated on a large dataset or (d) KOC values taken from existing pesticide properties databases.
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