Nitrogen Mineralization in Sludge Treated Soils as Influenced by Temperature and Soil Water Content

Effect of temperature and water content on the mineralization of N in two soils treated with sludge was investigated in incubation studies. Amount of NH₄⁺ -N decreased and NO_3--N increased with the increase in temperature from 15 to 35°C. At 45°C, NH_4⁺ -N was higher than at 25 and 35°C but lower than that at 15°C. Amounts of NO_3⁻ -N were less at 45°C than those at 35 and 25°C but were more than that at 15°C. Mineralized N increased with increasing temperature from 15 to 35°C and decreased at 45°C. Mineralized N was higher in the sludge treated soils than in untreated ones at each temperature. Rate of nitrification was fastest at field capacity followed by 50 per cent field capacity and wetting and drying. Nitrification was almost inhibited at saturation and flooding. NH₄⁺ -N was the major form of N at saturation and flooding but NO₃⁻ -N was the major form of N at field capacity.