Biochar is a porous charcoal-like material produced from pyrolyzing (or heating without oxygen) organic biomass. It is increasingly being researched for its potential to improve soil fertility and soil health, increase agricultural production, and sequester carbon (C) long-term in soils. However, biochar properties vary depending on feedstock and pyrolysis conditions (e.g., temperature, length of time, etc.) and its effects can also differ across soil habitats. My thesis research examines how biochar amendments can alter soils and the broader impact it may have on agroecosystems. In my first chapter, I sought to understand how different biochar types and nutrient additions could impact plant symbioses with arbuscular mycorrhizal fungi (AMF) through a six-month greenhouse experiment. My results indicated that biochars can mitigate low soil nitrogen (N) and phosphorus (P) levels for plant growth and that N from organic substrates was utilized by AMF more than P from organic substrates. These findings can inform agroecosystem weed management practices when amending soils with nutrients or biochar. In my second chapter, I examined how biochar type and application rates may impact soil C stabilization mechanisms in different soils for one-year and four-year aged samples. Overall, I found the wood-based biochar and the higher application rates to have the greatest effects, which were strongest in the coarsest soil type. Both biochars showed evidence that their recalcitrant structure influenced their stabilization, potentially more than other processes such as aggregation or organo-mineral associations, although this may change over time. Thus, I found biochar can be used to sequester C, improve soil health, and maintain sustainable agroecosystems.
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