Mineralization and Crop Uptake of Nitrogen from Textile Manufacturing Wastewater Sludge Cake

Wastewater sewage sludge cake from textile manufacturing was evaluated by soil incubation experiments and a greenhouse experiment for use as a soil amendment to provide crop N. Although the sludge had 96% of N in organic combination, 20% of total sludge N was released to soil as mineral N over 28 days. N mineralization from the sludge was indistinguishable from that seen for alfalfa shoot in parallel incubations. However, nitrification inhibition was seen for the alfalfa amendment. Soil respiration was low for the sludge treatments compared to the alfalfa treatments, suggesting that carbon substrates in the sludge were less easily broken down. A second incubation experiment indicated that fine fragmentation of the sludge is not necessary to ensure mineralization proceeds. In a greenhouse experiment, sludge N was approximately 25% as available to Zea mays L. as NH4NO3. The textile manufacturing sludge offered potential to offset N fertilizer requirement.