By DV CALCINO; AP HURNEY; WP SCOUGALL; HT SLATTERY
ORGANIC compost produced in Cairns by Sita Environmental Solutions contains
significant levels of organic matter, moisture and nutrients. To assess the value
of the product to sugarcane production, a replicated experiment was established
in 2004. The trial was analysed for the next three crop years to: investigate the
impact of the compost on cane and sugar yields; determine the effect of the
compost on soil pathogens; determine the influence of the compost on heavy
metal levels in sugarcane juice; and determine if fertiliser rates on commercial
sugarcane farms could be reduced after the application of Bedminster compost.
Over the three-year crop cycle, compost applied prior to planting produced
significantly higher cane and sugar yields compared to the control treatment
where only annual applications of nitrogen, phosphorus and potassium were
made. Addition of compost had a large impact on some soil nutrient levels and
soil pH. Soil nitrate nitrogen, total nitrogen, calcium, magnesium, potassium,
copper and zinc levels were all increased significantly when compost was
applied. Soil pH and organic carbon also increased significantly. The addition of
compost had no impact on the levels of heavy metals detected in sugarcane juice
or on either the beneficial or harmful soil nematode populations.