Carbon, Nitrogen, and pH Analysis in Bulk Soil and Rhizosphere Samples in CSUSM Wetlands

Abstract

Differences in vegetation composition can significantly impact soil carbon (C), nitrogen (N), and pH levels. The purpose of the current study was to measure how C, N, and pH levels vary with bulk and rhizosphere wetland soil samples at California State University San Marcos. The procedure entailed randomly collecting samples from the upper 20 cm soil layer from the three main vegetation types in the wetland: lowland (L), riparian (R), and sedge (S). From each site, eight bulk samples were collected, and eight rhizospheric samples were extracted from the bulk soil (n = 24). All of the samples were then isolated, dried, ground to a fine powder, then analyzed using both a CHN analyzer via dry combustion, and a pH meter. Statistical analysis was conducted through Jamovi, and graph creation was utilized through Excel. Non-parametric tests were conducted on data samples where transformations did not accommodate for normality. Results of the study showed that our hypotheses were partially true: though we were correct that the rhizosphere did have a higher C% compared to bulk soil, significance of this difference was only found in L and S, but not for R. Similarly, though we found that the rhizosphere was more acidic compared to bulk soil, significance of this difference was only found in L and S, but not for R. Finally, our results showed that there was no significance in average N% between L, R, and S in either rhizosphere or bulk soils. These findings may help to better understand the processes involved for successful agricultural practices, namely if in the possible future, there could be technology utilized to manipulate carbon, nitrogen, and pH variations in soil.