Evaluation of Methane Generator Sludge as a Soil Amendment

Abstract

AbstractSludge obtained from a methane generator charged with fescue hay (Festuca arundinacea L.) was evaluated as a potential soil amendment. The amounts of C, K, and Na were greater in the rescue hay than in the sludge. However, Ca, Mg, N, P, S, and Zn were more concentrated in the sludge than in the fescue hay.Air‐dried sludge was mixed with a Menfro silt loam soil (fine‐silty, mixed mesic Typic Hapludalfs) to give 10, 20, 40, and 80 g sludge/kg. Sludge addition had no consistent effect on seed germination. The number of seeds germinating in all treatments was: corn (Zea mays L.) 89 to 98%, sorghum (Sorghum bicolor L.) 94 to 97%, soybean [(Glycine max (L.) Merr.] 90 to 97%, and wheat (Triticum aestivum L.) 98 to 100%.The addition of sludge increased the quantity of water held by the Menfro soil at matrix potentials of −10, −33, and −100 kPa. Available water held between −10 and −100 kPa matrix potential increased as the amount of sludge added increased. Nutrient uptake by wheat and sorghum showed that the addition of 80 g sludge/kg was equivalento adding 400 mg P/kg soil, but, due to the high C/N ratio, did not supply adequate N.