MICROBIAL CARBON CYCLING UNDER CLIMATE CHANGE: USING SOIL TEXTURE GRADIENTS TO UNDERSTAND AGRICULTURAL CARBON STORAGE

As dramatic shifts in climate patterns manifest globally, intensifying drought and more episodic precipitation will produce alternating conditions of desiccation and saturation in soils. These moisture fluctuations have consequences for the efficiency of microbial carbon (C) cycling and soil C storage. This project will explore how agricultural soil C dynamics will respond to precipitation change, focusing on the role of soil texture in mediating this response. Understanding the soil texture and moisture controls on microbial C dynamics is critical for predicting whether C storage in agroecosystems will be resilient to shifting precipitation patterns; insight from this project will inform soil C management that is mutually beneficial to agricultural production goals and climate adaptation priorities.The primary goal of this project is to understand how soils of different textures respond to episodic precipitation, and whether this will change the potential for long-term carbon storage in agricultural lands.The main objectives are:Objective 1: Compare microbial Carbon Use Efficiency (CUE) and associated soil C storage and loss patterns under stable moisture (i.e., saturation or desiccation), fluctuating moisture (i.e., alternating periods of desiccation and saturation), and optimal moisture across gradients of soil texture. Moisture treatments will be imposed across natural and constructed soil texture gradients in lab microcosms to evaluate: (1) CUE by quantifying carbon-13inputs stored as microbial biomass andlost as respired carbon dioxide over 24 hours; (2) rates of soil C storage and loss by tracking the fate of carbon-13 inputs into microbial biomass, soil organic matter, and respired carbon dioxide after three months of moisture manipulations; (3) temporal shifts in microbial community composition.Objective 2: Engage with agricultural practitioners to disseminate research findings. Considering the need to produce and communicate soil health research as climate change progresses, PD Luthard will pursue three channels through which to apply and convey new knowledge critical to diverse stakeholders: (1) Extension publications; (2) outreach at conferences that attract agricultural professionals; and (3) workshops at the Penn State Student Farm and annual Ag Progress Days event. Outreach activities will be tailored toward farmers and land managers interested in learning more about soil health and fertility, managing their soil C stocks, and sequestering atmospheric carbon dioxide in cropland.Objective 3: Design laboratory courses to support original undergraduate research experiences related to microbial nutrient cycling in agricultural soils. Greater participation and equitable representation in the agricultural sciences is essential and can be achieved in part by providing opportunities for students who may not otherwise have the flexibility to participate in agroecological research. PD Luthard will develop mentorship and teaching skills by designing embedded research experiences in collaboration with Dr. Denise Finney at Ursinus College. PD Luthard will create a Course-Based Undergraduate Research Experience (CURE) under the mentorship of Dr. Finney, including curricula, syllabi, lab manuals, and other course materials. The CURE will be piloted in an undergraduate lab course at Ursinus College and then implemented at Penn State as PD Luthard co-teaches and then acts as the instructor of record for Soil Ecology, an existing undergraduate lab class.