Long-term profitability of liming to manage soil acidity in sugarcane: Tully, north Queensland

Management of soil fertility is an important factor influencing the long-term profitability of sugar production systems. In this respect, soil acidification associated with repeated cropping may result in declining productivity in the absence of effective ameliorative measures. This paper outlines the results of an economic analysis of a long-term liming trial, undertaken in the Tully district of north Queensland. These results highlight a lag period of up to four years from initial application before the benefits of liming were obsetved in yield increases. In addition, the responses obsetved were cumulative over an 18-year period. The best economically viable liming treatment comprised a 5 t/ha lime application at the initiation of the trial and a further 1.25 t/ha lime on each occasion the crop was replanted. It is coneluded that frequent prophylactic applications are an extremely reasonable insurance premium to maintain sustained yields.