SUSTAINABLE GARDENING INITIATIVES AT BROWNFIELD SITES
Authors:Chammi Attanayake, Blanca Calderon
- Monica Palomo, Assistant Professor, California State Polytechnic University, Pomona
- Ganga Hettiarachchi, Assistant Professor, California State Polytechnic University, Pomona
SUSTAINABLE GARDENING INITIATIVES AT BROWNFIELD SITES Blanca Calderon1, Chammi Attanayake1, Dr. Mónica Palomo2 and Dr. Ganga Hettiarachchi2 1 Department of Civil Engineering, California State Polytechnic University, Pomona; 2Department of Agronomy, Kansas State University. The objective of the project was to test soil quality of new or established community gardens in the Southern California urban area. Test plots were established in urban mildly contaminated soils. The plants used for testing (carrots, beets, lettuce and radish) all had different uptake and growing characteristics. They were grown for two seasons with and without site-specific suitable best management practices (BMPs). Compost, lime and compost +lime were used as treatments to reduce the amount of lead (Pb) contamination in the soil since the current concentration is more than the acceptable amount of lead in root crops (1.5mg/kg). Soil testing was conducted before and after gardening and harvesting. Produce was tested to monitor mobility of contaminants detected in soil. Moreover, bioaccessibility of soil lead was measured using physiologically based extraction test (in vitro method) to assess accessibility of soil lead to humans from ingestion of mildly contaminated garden soil. The results will verify which treatments are most effective and thereby educate the community members on which BMPs should be carried out to keep contaminants (less mobile) in the soil phase. The horse manure treatment did not have a significant effect in the plant uptake of lead. The lead concentrations in the root crops were still above 1.5mg/kg. Bioaccessible lead concentrations ranged from about 17 mg/kg (in the control soil and lime treated plots) to 12.5 mg/kg (in both lime and compost added plots) indicating bioaccessibility of lead in these soils are low. Also the addition of organic matter (compost) further reduces the lead availability to plants and humans.