Beneficial use of byproducts to reduce phosphorus loss from agricultural land

Industrial byproducts, including drinking water treatment residuals (DWTR) and iron waste products, wood-derived fly ash, biosolid incinerator ash, foundry sand and manufactured material, can be promising materials for phosphorus (P) removal from agricultural systems. In this study, nineteen byproducts were evaluated for the P sorption capacity and effectiveness when co-blended with biosolids (low P content) and poultry manure (high P content). Most DWTR demonstrated high P sorption capacities (12.9-44.8 g kg^-1), with high amorphous aluminum (Al_ox) and iron (Fe_ox) content. Only one iron byproduct exhibited exceptional P removal performance despite varying results from other iron-rich byproducts. Co-blending study revealed that application rates of 30 % were optimal, achieving water-extractable phosphorus (WEP) reduction exceeding 80 % while simultaneously reducing phosphorus saturation index (P_sat) to below 100 %. However, metal content analysis identified environmental concerns for some materials, highlighting the importance of thorough characterization before land application. The strong correlation between P sorption maximum (P_max) normalized across byproduct application rates (P_max × DWTR application) and reductions in WEP demonstrated a reliable predictive tool for determining P_max without the multipoint batch equilibrations necessary for the Langmuir model and field applications of these byproducts. These findings provide valuable insights for sustainable P management in agricultural systems while addressing waste disposal challenges.