Functional Soil Health

Nanoparticles are a hot topic in agriculture due to their unique properties that come from their small size. During my PhD I studied how nanoparticles can influence soil health.

My collaborators and I found that despite similarities in nanoparticle fate in soil taken from agricultural and wild systems, their influence on microbial community size was land use dependent. Microbial communities in wild systems (grassland and forest) reacted differently than microbial communities in agricultural systems (conventional and organic). Specifically, in wild systems, microbial community size and respiration decreased with Cu exposure. In agricultural systems, community size was unaltered but respiration was impaired. The results of this study indicate that copper application in agricultural systems may impair nutrient cycling. However, CuO nanoparticles appear to influence microbial communities less than copper salts which are often used as fungicides in agriculture.

Soil sampling locations at Russell Ranch
Relationship between soil organic carbon and microbial community size.
Distribution of applied copper from CuCl2, 16nm CuO nanoparticles, 42 nm CuO nanoparticles, and micron sized CuO particles (bulk) after a 70 day incubation in the same soil managed either for conventional agriculture or as a riparian oak forest. X-ray absorbtion spectroscopy indicated that CuCl2 and 16 nm CuO dissolved completely and were bound by silicates and organic matter. 42 nm CuO and bulk CuO dissolved to a lesser extent. Despite differences in soil chemical properties, the fate of Cu was consistent across management systems.
Relationship between soil respiration and microbial community size after treatment with CuCl2 in turquoise, 16 nm nanoparticles in blue, 42 nm CuO nanoparticles in periwinkle, micron sized nanoparticles (bulk) in dark blue, and the no copper control in teal.