A comparison of soil tests for available phosphorus in long‐term field experiments in Europe

Summary

This comparative study evaluated five established soil phosphorus extraction methods across 218 samples from long-term field experiments (some >100 years old) spanning five European countries and 11 soil types. Whilst all five tests correlated positively with crop yield, quantity-based tests (ammonium oxalate, ammonium lactate, Olsen P) generally outperformed intensity-based tests (CaCl₂, DGT) in Mitscherlich models, though intensity tests showed less variation in critical P values across soil types. The authors conclude that no single test was clearly superior except that ammonium oxalate performed poorly, and that combining quantity and intensity tests provided marginal improvement over single tests.

UK applicability

The study provides critical phosphorus values validated across European soil types, likely applicable to UK conditions given the inclusion of long-term field trials across the continent. However, the findings suggest that UK practitioners should consider using multiple P tests rather than relying on a single extraction method, and that locally calibrated critical values may be necessary for different soil types.

Key measures

Crop yield response data; phosphorus extractability via five different soil tests; goodness of fit in Mitscherlich models; critical phosphorus values; correlation between soil P tests and crop yield across soil types

Outcomes reported

The study compared five soil phosphorus extraction methods (ammonium oxalate, ammonium lactate, Olsen P, CaCl₂, and DGT) in their ability to predict crop yield across 218 soil samples from 11 different soil types in long-term European field experiments. The performance of quantity-based versus intensity-based tests was evaluated using Mitscherlich models and critical P values.

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