Effects of irradiation on sludge organic carbon and nitrogen mineralization

• Published in: Soil biology & biochemistry 1997-09, Vol.29 (9), p.1363-1370
• Main Authors: Wen, Guang, Voroney, R.Paul, Winter, Julien P., Bates, Thomas E.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; Soil-plant relationships. Soil fertility. Fertilization. Amendments
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/S0038-0717(97)00057-6

Irradiation used to eliminate pathogens in sewage sludge may deleteriously affect properties of sludge organic matter. Three anaerobically digested, dewatered sewage sludges were irradiated with gamma-irradiation at absorption doses of 0, 6 and 12 kGy, respectively, then mixed with a soil and incubated for 16 wk. Evolved CO 2 and concentrations of NH 4 +N and NO 3 −N in the sludge-soil mixture were measured. The effects of irradiation were not consistent in the three sludges tested. Irradiation did not significantly affect sludge organic C nor N mineralization in Guelph sludge (GS). However, in sludges from Ottawa (OS) and Toronto (TS), C mineralized in irradiated treatments was less than from the non-irradiated treatments. In response to slower organic matter decomposition caused by irradiation in the OS and TS, the inorganic N concentrations were higher with irradiated than with non-irradiated in the OS, but the converse was true for the TS. This was probably related to the difference in C-to-N ratio of the organic matter (19.5 in OS and 9.5 in TS). Increasing the irradiation doses did not significantly affect inorganic N concentrations with the OS, but with the TS, the high dose (12 kGy) treatment resulted in higher C and N mineralization than did the low dose (6 kGy).