Phosphorus Runoff From Soils Receiving Liquid Dairy And Swine Manures Amended With Mine Drainage Residual

Concern over nutrient runoff from agriculture has prompted considerable research on amendments to limit phosphorus (P) solubility of manure slurries and P mobility following land application of the slurry. The concept of solving one industry's problem with another industry's problem is attractive, but successful examples are uncommon. Mine drainage residual (MDR), generated from the process of neutralizing acid discharge from coal mines, has been shown to reduce soluble P in soils, sediments and manure slurries. We therefore sought to test whether amending manure slurries with MDR was effective at reducing P in runoff once that slurry was applied to agricultural soils. A series of simulated rainfall experiments revealed that amending dairy manure slurry with MDR resulted in significantly less flow weighted dissolved P concentrations and loads in runoff. However, the same effect was not observed with runoff from soils amended with swine manure slurry, despite a greater reduction of water extractable P in swine manure slurry with MDR addition than in dairy manure slurry. This study underscores the value of testing amendments under field conditions before making manure management recommendations.