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Livestock Nutrient Management The Mobile Struvite Project: Removing and Capturing P from Liquid Dairy Manure

Capturing Phosphorus from Dairy Manure in the Form of Struvite on 30 Dairy Farms in WA State

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), a slow release, easy to handle, P based fertilizer, for off-farm export as a fertilizer source. Each farm has a unique need for P removal to reach a whole farm nutrient balance.

The Mobile Struvite Project demonstrates the farm-scale deployment of a mobile struvite system for economical and efficient means of P capture and subsequent transport of nutrients from a region or P density to an area of forage production that needs supplemental P.

This video 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.