Land Disposal of Liquid Sewage Sludge: I. The Effect on Yield, in vivo Digestibility, and Chemical Composition of Coastal Bermudagrass (Cynodon dactylon L. Pers)

Abstract

AbstractThe disposal of liquid sewage sludge on established Coastal bermudagrass sod was studied over a 2‐year period. Rates of sludge application up to 20 cm/year were compared with a conventional fertilizer treatment.In 1969 there were no significant differences among the three highest sludge rates and all sludge rates were superior to chemical fertilizer (224‐37‐97 kg/ha NPK) in forage production. In 1970 no significant differences were found among the three top rates of sludge and a higher rate of chemical fertilizer (358‐112‐224 kg/ha NPK) that was used. Sludge applications had little effect on in vivo digestibility of the forage. The K level of the forage was initially increased by sludge applications but steadily declined during the last half of the 1969 season and the entire 1970 season. Sludge applications increased the N and Na level of the forage but had little or no effect on P, Ca, Mg, Mn, B, Cu, Mo, and Ni. Zinc content of the forage increased with increasing sludge rate and number of application through the second clipping in 1970. Although Zn levels of 340 ppm were found no reduction in yield resulted. There was no significant survival of coliform bacteria on the forage at harvest. Results of the investigation indicate that Coastal bermudagrass is a well‐adapted crop for sludge disposal areas.