In agricultural soils, a large portion of C in crop residues (i.e. non-harvested plant parts) is annually lost to the atmosphere due to the low C use metabolism of soil microorganisms suffering C and N imbalance. In this study biosolids (treated sewage sludge) were applied for 13 years (1972–1984). The sequestration rate of crop residue-C in the soils was measured over 34 years (1972–2006), revealing dramatically greater sequestration rate in biosolids-amended soil (32.5% of total crop residue-C) versus unamended soil (11.8%). The study concludes use of biosolids is a valid approach to transform agricultural soils from current C-neutral status to a C sink.