Phosphorus transformation and transport from fertilizers and manures

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Phosphorus (P) is an essential element for all forms of life including agricultural crops.The soil supply of P is augmented by fertilizer addition to ensure economic yield. However, the fertilizer use efficiency of P by agricultural crops rarely exceeds 20% in the year of application. Increasing the efficiency of fertilizer P by manipulating the chemistry of the fertilizer band will produce both agronomic and environmental benefits. This is through a reduction in P fertilizer and residual soil P thereby reducing the risk of P loss to surface waters. For example, in 2013, Lake Winnipeg, the 10th largest body of freshwater and 3rd largest reservoir of hydroelectric in the world, was declared as the “Threatened Lake of the Year” by the Global Nature Fund. There is therefore an urgent need to better understand the dynamics of P in agricultural soils to aid the establishment of practices that effectively reduce the loss of P from soils to surface waters. My research program investigates the transport and transformation of P in soil following additions of fertilizers and manures. For the next 5-year cycle, I propose a series of innovative studies on fertilizer and manure P that will address some of the agronomic and environmental challenges of managing P. In the area of agronomy, my long-term objective is to generate a better understanding of soil P dynamics that can be used to significantly increase the efficiency of fertilizer P. Studies that my group has conducted to date have shown that the mobility and solubility of P is increased by the co-application of sulfate salts with P. We have also discovered that the species of P that are formed in model soils was influenced by sulfate salt. We therefore need to identify and quantify the species of P formed in real soils and relate these to increased solubility of P when sulfate salts are added to P. My HQP and I will study the relationship between soil properties and response to sulfate salts and develop a sulfate salt response index for agricultural soils. I will use chemical equilibrium model to provide mechanistic information on P sorption and precipitation in soils. We will compare the movement and solubility of P from different animal manure bands to that of P fertilizer. The information that we generate will aid our efforts at finding the right formula for improving fertilizer use efficiency of P and the management of manure P. If P use efficiency is increased by 10%, for example, there is a saving of $60 million per annum by Canadian farmers in P fertilizer cost. This 5-year cycle of Discovery Grant research will support the training of 2 PhD and 3 MSc students who will gain skills in the area of P chemistry and the use of modern spectroscopic techniques. They will be desirable employees as scientists in government labs and departments, academics, and fertilizer industry. Because of the increasing importance of P across different jurisdictions, Canada needs more people trained in this area.