Effects of Biosolids Based Soil Products on Soil Physical and Chemical Properties in Urban Gardens

Urban Farm DB summary

A study in Tacoma, Washington, evaluated the effects of two biosolids-based soil products, Tagro and GroCo, on soil physical and chemical properties in three urban community gardens over two growing seasons. Amendments were applied at 200 Mg ha−1 dry weight in the first year, with half receiving an additional 200 Mg ha−1 in the second year. Biosolids did not significantly affect total soil metal concentrations, but increased water infiltration rates from 10.1 ± 0.95 ml min−1 to 51–212 ml min−1, decreased bulk density from 1.07 ± 0.01 g cm−3 to 0.51–0.77 g cm−3, and increased total carbon, nitrogen, and available phosphorus. Biosolids addition also decreased soil pH from 6.43 to 5.35–5.75.