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Abstract

Soil systems have the ability to store large amounts of carbon for both short and long periods of time, much like other carbon pools such as oceans and forests. As increased amounts of carbon dioxide are released into the atmosphere via anthropogenic means, including the agricultural industry, scientists have been researching how to increase the amount of carbon cycled from the atmosphere and into soils as a climate change mitigation strategy. Soil systems have the capacity to sequester carbon in part due to fungal and bacterial community activity. Differences in soil microbial biomass levels between annual and perennial agricultural systems will affect the amount of carbon sequestered from the atmosphere. Prior studies have shown that annual agricultural systems tend toward lower microbial biomass levels due to the constant disturbance in soils via management practices such as tilling (which breaks up fungal hyphal and bacterial communities) and relatively shallow root systems. On the other hand, perennial agricultural systems tend toward higher microbial biomass levels due to less routine disturbance of the soils and deeper root systems. In this study, we examined the relationship between microbial biomass (fungal, bacterial, and total) and percent organic carbon in soils systems managed for annual crops (diverse vegetables) versus perennial crops (apple orchard) at Loy Farm, a one acre farm located on Elon University’s campus. We used a standard loss-on-ignition (LOI) procedure and the microBIOMETER® test kit to determine total soil organic carbon (SOC) and microbial biomass levels in 200 soil samples (50 at 0-10 cm depth and 50 at 10-30 cm depth in each condition). The five research questions explored in this study are:

RQ1: Will the annual field or perennial field contain more soil organic carbon (SOC)?

RQ2: How will SOC vary with depth (0cm-10cm vs. 10cm-30cm) in annual and perennial conditions?

RQ3: How will fungal, bacterial, and total microbial biomass compare between perennial and annual conditions?

RQ4: How will fungal, bacterial, and total microbial biomass vary with depth (0cm-10cm vs. 10cm-30cm) between perennial and annual conditions?

RQ5: Will the annual field or perennial field show a stronger correlation between microbial biomass and SOC?

Data analysis determined that the annual field at Loy Farm contains more soil organic carbon than the perennial field at all depths. On the other hand, the perennial field contains more fungal, bacterial, and total microbial biomass compared to the annual field at all depths. Finally, the annual field showed a stronger correlation between microbial biomass and soil carbon than the perennial field. The data collected in this experiment will contribute to future climate change mitigation research and soil health analysis.

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