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

Abstract

The yields of tomato (Lycopersicum esculentum) and mustard (Brassica juncea) plants, grown on a low‐pH, compacted silt‐loam soil, were generally significantly higher in plots treated with composted sewage sludge and composted yard wastes, than in plots receiving applications of commercial N‐P‐K fertilizer. The results of chemical and physical soil analyses indicated that apart from ameliorating the poor physical properties of the compacted soil, additions of the composted organic amendments significantly increased soil pH, organic matter content, and the available supplies of phosphate and magnesium in the soil. Chemical analyses of the edible portions of the plants for the uptake of heavy trace metals, such as lead and cadmium, indicated that the levels of these trace elements in the plants were not high enough to warrant any health concerns, and the levels were well within the acceptable ranges established by other researchers.

Key words:

• urban garden
• lime
• compost
• mustard
• sludge
• yard
• waste
• metal