Improved understanding of soil organic matter stabilization in agricultural systems with contrasting input strategies.

点击翻译按钮获取中文摘要

The long-term objectives of my research program are to understand how soil organic matter (SOM) composition and distribution in the landscape can be managed to promote sustainable agro-ecosystems. Soil organic matter buildup is recommended to develop healthy soils. It is also frequently suggested that healthy soils are better able to resist environmental stresses. This is becoming increasingly important as climate models are predicting more frequent and severe weather events, along with a general warming trend for the most agriculturally productive regions in Canada. The stability of soil organic matter (SOM) as it relates to resistance to microbial degradation has important implications for nutrient cycling, emission of greenhouse gases, erosion control and C sequestration. Most studies discuss the contributions of total SOM toward healthy and resilient soils; however, we know that SOM is heterogeneous. SOM composition is influenced by the types and amounts of plant and animal residues (or inputs) that the soil receives. Since the molecular structure of SOM influences its persistence in the environment, it is critical to understand how these inputs influence SOM composition because it has important implications for nutrient cycling, emission of greenhouse gases, erosion control and C sequestration. My research expertise combines a strong understanding of soil systems and state-of-the-art instrumentation used to understand ecosystem influences over the biogeochemistry of SOM. In this proposal, I use these advanced methods explore how different agricultural input strategies contribute to the overall composition of SOM. The overall goal is to identify SOM management strategies that would contribute to agroecosystem sustainability and resilience. The specific objectives of this proposal are: 1) Establish link between carbon inputs from crops and manure on the biological stability of SOM; 2) Elucidate the relationship between thermal stability of SOM and microbial substrate use efficiency; 3) Identify key organic matter composition differences from soils under contrasting organic input types and amounts using advanced spectroscopy; 4) design a process model which includes microbial, ecosystem and chemical controls over SOM cycling in agroecosystems. Findings from this work will have a significant impact on our fundamental understanding of how soil organic matter from inputs contributes to the mechanistic nature of SOM stability. Because soils selected for characterization in this study will come from a range of land management practices, we will be able to make robust, science-based recommendations for sustainable agricultural practices. Ultimately, this will lead to a better understanding of how agroecosystems can sequester carbon and be future-proofed against increased uncertainty and variability in climate and weather events.