Surface-Applied Biosolids Enhance Soil Organic Carbon and Nitrogen Stocks but Have Contrasting Effects on Soil Physical Quality

Figure 1

Effect of biosolids application for 8 yr (midterm; solid symbols) at four treatment rates on (a) soil organic carbon stocks (Mg C ha⁻¹, 0–45 cm); (b) total nitrogen stocks (Mg N ha⁻¹, 0–45 cm); and (c) carbon-to-nitrogen ratio (0–45 cm). Open symbols show long-term applications of 20 Mg biosolids ha⁻¹ yr⁻¹ for 20 yr (not included in regression shown). The asterisk indicates significant difference between midterm and long-term treatments ().

(a)

(b)

(c)