Novel microcosm design to test phosphorus desorption from static soil samples using iron oxide-impregnated filter papers.

Iron oxide-impregnated filter papers (FeO) facilitate the study of soil phosphorus (P) desorption, availability and dynamics. However, many studies use homogenized and saturated shaking FeO soil systems, hindering opportunities to resolve environmentally relevant experimental objectives. This study created and evaluated a static microcosm to study soil P dynamics with FeO papers. The microcosm design is simple: silicone rubber is glued to the bottom of a piece of polyvinyl chloride (PVC) pipe. The soil is packed to a known bulk density into the PVC pipe. Finally, the top of the PVC pipe is sealed with a fine nylon mesh, allowing water exchange to the overlaying filter paper. To validate the systems, we created three proof-of-concept tests. The first determined whether FeO filter papers remove statistically significant P compared to a control. The second test examined the effect of soil water content before finally testing the influence of amendment sources on the amount of P desorbed. Results show that FeO papers paired with the microcosms desorb soil P, while the soil water content and amendment type impact total soil P released. Consequently, the soil microcosm design allows users to test and examine soil P processes with FeO papers under new experimental conditions.•Phosphorus desorption studies using iron oxide-impregnated filter papers are limited by homogenized and saturated extractions. Consequently, a static microcosm design was created to allow for manipulation of experimental factors.•Results from three proof-of-concept tests confirm that using iron oxide-impregnated filter papers with static microcosms promotes phosphorus desorption, allowing for adjustable experimental designs.