University of Saskatchewan
Department of Soil Science
College of Agriculture and Bioresources

Environmental Soil Chemistry

Phosphorous speciation in soils, manures, and biosolids

Phosphorus is a required macronutrient for plant growth, and the widespread use of P and N fertilizers is largely responsible for the explosion in crop yields over the last 50 years and the ability of modern agriculture to feed the world cheaply and efficiently. However, excessive application of N and P via animal manures and biosolids is now becoming one a widespread environmental problem throughout the world. This is because P is also a limiting nutrient for growth in surface waters, and an input of P can cause algal blooms, eutrophication, and even red tides and dead zones in marine systems. To minimize the risk of phosphate in regions receiving large amounts of manures and biosolids, it is important to develop an integrated nutrient management plan that tailors the application, agronomic practices, and land management practices to the environmental risk.

Our research involves using x-ray absorption spectroscopy to determine the chemical form of phosphate (organic, aqueous, adsorbed, precipitated as Ca, Fe, Al minerals, etc) in manures, litters, biosolids, and soils. We can utilize this technique to evaluate the success of different management strategies sometimes used to decrease the environmental risk of PO4: (i)chemical amendments added to manures or biosolids prior to land application (ii) changes in animal diet to reduce the amount of labile phosphate in manures and (iii) changes in animal genetics to make them more efficient at digesting phosphate. For more information, see the following studies: