This project aims to investigate management practices for use of municipal biosolids as a crop fertilizer and to quantify the effect of these practices on GHG emissions. Biosolids are a by-product of wastewater treatment plants and contain appreciable quantities of organic and inorganic N, as well as other plant nutrients (e.g., P, K, Ca, Mg), making them a valuable fertilizer for crop production. Sustainable nutrient management requires that we investigate ways to circularize the nutrient economy, and recycling the nutrients in biosolids is an important way to do this. We should strive to optimize the nutrient use efficiency of biosolids by crops, while minimizing greenhouse gas emissions.
With rapidly growing urban populations and the construction of modern wastewater treatment facilities, Canadian jurisdictions are dealing with greater volumes of biosolids by land application, but there are still significant knowledge gaps about the environmental impacts of this practice. Since biosolids are often considered as waste to be disposed of, there are no best management strategies for optimizing nutrient recovery from biosolids in cropping systems that take into consideration site-specific climatic conditions, soil characteristics, or biosolids pre-treatment. Organic N mineralization in biosolids-amended soils produces inorganic N, which is both plant-available and susceptible to environmental loss. A sound understanding of N availability from biosolids during and between cropping seasons will do much to allow the efficient use of that N by crops and reduce the risk of NO3- leaching and N2O emissions due to over-application or poor management. Economic gains can be expected on farms due to improved yields and the purchase of less commercial fertilizer.聽聽
The main objective of this project is to assess the effect of biosolid pre-treatment and application methods on N use efficiency, greenhouse gas emissions, and C sequestration, under three distinct climatic conditions in Canada: Humid continental (Montreal), Atlantic maritime (Nova Scotia) and semi-arid Prairie (Edmonton). The project will link field-based experiments to systems models, to simulate and validate nutrient and GHG fluxes and assess the impact of management techniques on nutrient use efficiency and GHG emissions. Three seasons of replicated experimental data on corn or barley yields, aboveground biomass and nutrient content, and greenhouse gas emissions will be collected and analyzed to quantify the treatment effect on N use efficiency and emissions of CO2, N2O and CH4 in all three locations.
The data obtained will be used to optimize and validate the Biosolids Emissions Assessment Model (BEAM) and Holos models as predictive tools to aid farmers and other stakeholders to make informed decisions that will enhance the fertilizer benefit of biosolids use while minimizing GHG emissions. The collaborative and inter-regional nature of the project and the attention to comprehensive knowledge dissemination will result in best management practices of national and international utility.聽
Deliverables from this project include IPCC Tier 3 methods (mathematical models) for predicting GHG emissions from biosolids application, and best management practices for minimizing those emissions, which can directly be integrated into decision-making by individuals or groups of farmers.聽聽
