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INFLUENCES OF YARD MANAGEMENT INTENSITY ON URBAN SOIL BIOGEOCHEMISTRY

Viviana Penuela Useche, David Lewis.

University of South Florida, Tampa, FL.

Irrigation with reclaimed water is an increasingly popular water conservation strategy, yet the high salinity and nutrient content of reclaimed water has the potential to negatively affect soil properties. At 40 households in urban, subtropical Tampa, Florida, we surveyed residents for their lawn management behaviors and quantified irrigation water and soil chemistry. We tested whether there are distinct lawn management systems characterized by systematic differences in reclaimed water use and irrigation and fertilization practices. We then investigated whether soil biogeochemistry responds to lawn management systems. Three management behaviors co-occurred, as households that used reclaimed water tended to fertilize and irrigate more frequently. Reclaimed water had significantly higher conductivity and phosphate content than potable water. Distinct, high-amendment and low-amendment lawn management systems are thus evident. Residential soils receiving the high-amendment strategy exhibited higher conductivity and microbial biomass than soils receiving a low-amendment strategy. These findings suggest that the high-amendment strategy increases the input of some nutrients to soil and acts as a nutrient resource for soil microorganisms. These results further suggest that hierarchical social interactions between municipalities and individual households should be incorporated into the emerging conceptual framework of ecological urbanization. Specifically, as municipalities make management alternatives (reclaimed water) available to households, they may introduce spatial ecological variability at the finer within-neighborhood scale. Residential lawn management affects regional water supplies both through water consumption and nutrient runoff, and these results could inform how reclaimed water is advertised as a conservation measure as well as a source of soil fertility.