Abstract:
BACKGROUND : There are concerns that fertilization using sludge in semi‐arid areas, where water is limiting, will compound the effect of drought, resulting in the decline of yield from potential salt accumulation. This study investigated impacts of annual sludge application at 0, 4, 8 and 16 Mg ha−1 on weeping lovegrass hay yield, crude protein (CP) content, rainfall use efficiency (RUE), nitrogen use efficiency (NUE) and trace metal uptake over eight consecutive years.
RESULTS : Both hay yield and RUE increased by 5–53% as the sludge rate increased. Hay yield was highest (13.3 Mg ha−1) during the wet season and RUE (27.1 kg mm−1) during the dry season. RUE was highest at sludge rates of 16 Mg ha−1 and NUE at 4 Mg ha−1. Similarly, municipal sludge application increased CP content as well as crop Cr and Zn uptake from the 16 Mg ha−1 treatment.
CONCLUSION : Results from this study indicated that eight consecutive years of treated municipal sludge application increased weeping lovegrass hay yield, CP content and RUE. Similarly, trace metal uptake by crop did not differ between the zero control and the 16 Mg ha−1 treatment, except for Zn and Cr, which showed a slight increment. Nonetheless, all trace metals remained well below the maximum tolerable dietary concentrations for domestic animals. © 2017 Society of Chemical Industry
