NZ connections to this study on P leaching. Check out older posts with the P tag… https://soilcarbon.org.nz/tag/phosphorus/

Conclusions

“The findings of this study indicate that P leached from organic arable soils can be greater than from mineral soils, and therefore, these organic soils require further investigation into reducing their P losses. Metal-enriched biochar, applied as an adsorptive layer below the topsoil, has the potential to reduce P losses from medium- to high-P organic soils but appear to be less useful in mineral soils.”