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BACKGROUNDThere 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 16Mg 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.

RESULTSBoth hay yield and RUE increased by 5-53% as the sludge rate increased. Hay yield was highest (13.3Mg ha(-1)) during the wet season and RUE (27.1kg mm(-1)) during the dry season. RUE was highest at sludge rates of 16Mg ha(-1) and NUE at 4Mg ha(-1). Similarly, municipal sludge application increased CP content as well as crop Cr and Zn uptake from the 16Mg ha(-1) treatment.

CONCLUSIONResults 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 16Mg 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. (c) 2017 Society of Chemical Industry