ALBERT

Description: Pulverized household refuse (C/N ratio of 60:1) was incubated with Guelph loam (refuse rate of 3.5 or 7%) and sufficient anaerobically digested liquid sewage sludge, liquid poultry manure or (NH4)2SO4 to result in an added waste C/N ratio of 45:1 to 15:1. Most decreases in dry weight occurred during the first 168 days, suggesting that the more readily decomposable organic materials were nearly decomposed by 168 days. Dry weight decreases suggested that rate of refuse decomposition was not influenced by amount of supplemental N or by N carrier, probably because the soil and/or the refuse supplied substantial N. Incubation of refuse and high-N waste with soil resulted in considerably lower nitrate levels than incubation of high-N waste with soil. Incubation of refuse with soil resulted in lower nitrate levels than incubation of soil alone. In most treatments including refuse, nitrate N decreased from 108 ppm to less than 10 ppm at 28 days, remained low until 168 days and then increased. At incubation termination (224 days), nitrate levels in most treatments including refuse were similar to or lower than that for the control (~130 ppm NO3−-N). However, nitrate N levels varied from 214 ppm to 534 ppm at 224 days for those treatments which included 3.5% refuse and the highest level of high-N waste. Decreases in total inorganic N increased with increasing amounts of inorganic N applied, suggesting that immobilization and/or losses through processes such as NH3 volatilization increased with amount of inorganic N applied. Results supported the conclusion derived from associated field and lysimeter studies that were reported elsewhere, that simultaneous land disposal of pulverized municipal refuse and high-N wastes such as liquid sewage sludge or liquid manure is feasible. However, the inorganic N supplying power of the soil should be determined before waste application so that waste levels can be adjusted to avoid large accumulations of nitrate.