REVISITING SOIL LEAD SPATIAL VARIABILITY AT AN URBAN COMMUNITY GARDEN

The Indiana State University Community Garden was first established in 2006 in an area that was once residential housing built circa 1920. Since 2006, the garden has undergone several expansions and modifications. Today the garden consists of 160 plots that local community members use to grow fruits, vegetables, and ornamental flowers. Most areas of the garden are restricted to planting annuals, but there is now also a perennial garden and an orchard. In 2012, the garden was evaluated for soil lead. In response to finding elevated levels of lead in some garden plots, the garden was reconfigured to either remove those areas or reduce the potential for lead mobilization. For example, 20 plots were lost, a greenhouse was installed in one area, and raised beds were established. This initial research was based only on the analysis of surface soils. The garden does have a no-till policy, but gardeners still have access to and use a cultivator. In addition, the garden has once again expanded. The purpose of this research is to re-assess the ISU Community Garden to evaluate the impact of gardening practices on the distribution of lead in soils. Previous research focused on surface soils only, but this project also includes sampling at a depth of 6 inches throughout the garden. The garden was divided into 200 samples areas uniformly distributed across the garden. Two soil samples from each location are collected using a soil auger and analyzed via portable X-ray fluorescence (pXRF). Samples are initially analyzed wet after collection. The samples are then dried and re-analyzed using pXRF. Initial results have identified new areas with elevated soil lead, which will be communicated to the gardeners. Once all of the data has been collected, we will be able to compare the spatial variability we see at the surface to the variability that was observed in 2012 to evaluate how gardening practices have impacted the distribution of lead in the garden. Ongoing work also includes using a simulated gastric solution to evaluate lead bioavailability across the garden at both depths.