Effects of using organic wastes as soil amendments in urban horticultural practices in the district of Columbia

Urban Farm DB summary

In the District of Columbia, tomato (Lycopersicum esculentum) and mustard (Brassica juncea) grown on a low-pH, compacted silt-loam soil were compared under plots treated with composted sewage sludge and composted yard waste versus plots receiving commercial N-P-K fertilizer. Yields were generally significantly higher in the compost-treated plots than in the commercial fertilizer plots. Chemical and physical soil analyses showed the composted organic amendments not only improved the compacted soil's poor physical properties but also significantly increased soil pH, organic matter content, and available phosphate and magnesium. Chemical analysis of the edible plant portions for heavy trace metals such as lead and cadmium found levels not high enough to raise health concerns, remaining within ranges established as acceptable by other researchers.