Associations between mineral materials and organic matter stabilize organic phosphorus (Po) in soils. Mineralization of Po provides bioavailable P and controls P availability in well developed soils. However, changes in forms and concentration of Po in mineral-associated organic matter (MAOM) during soil development remain largely unknown. We quantified Po stored in MAOM in soils along the Franz Josef soil chronosequence (0.06 ky to 120 ky), New Zealand. In this humid forest ecosystem, Po in MAOM contributes 13% - 22% of total soil Po at the profile-scale of 1 m depth, with the remaining Po in particulate organic matter. The contribution of Po in MAOM increases with increasing soil developmental degree. Near-surface subsoils contained a greater proportion of Po in MAOM than in the surface and deeper soils. These results demonstrate that MAOM can stabilize a considerable proportion of soil Po, particularly in matured soils, with a consequence for soil P availability and dynamics during long-term ecosystem development.

Storage of mineral-associated organic phosphorus during soil development

ACS Fall 2021

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