Struvite, a Recycled Form of Phosphorus from Dairy Manure, used as Fertilizer for Alfalfa Production

Approximately 27 % of the phosphorus that the cow eats is captured in milk and exported off farm, the remainder not used by the cows is excreted in manure. As a result, there has been an increased build-up of P in soils on farms without sufficient land base to use all the P in manure for crop production. To address these issues, a nutrient recovery system has been developed (a fluidized bed) for extraction of P from manure in the form of struvite (magnesium-ammonium-phosphate) for off-farm export as a fertilizer source. Struvite, a recycled form of phosphorus from dairy manure, and Mono Ammonium Phosphate (MAP) were applied to 30 acre and 60 acre sections of alfalfa fields at two commercial forage operations in Eastern WA. Results indicate that struvite is equivalent to MAP as a P source for commercial production of alfalfa.

This video production is part of the Mobile Struvite Project at Washington State University’s Livestock Management Program. This effort was supported by a NRCS Conservation Innovation Grant and by the Washington State Dairy Products Commission.