Enhanced efficiency fertilisers can reduce nitrogen runoff losses from sugarcane

Fertiliser nitrogen additions provides good return on investment for sugarcane production. Fertiliser nitrogen is highly water soluble, and in the Wet Tropics is available to being lost in surface runoff where it can in turn negatively impact the Great Barrier Reef. Recently, attention has been focussed on the potential for Enhanced Efficiency Fertilisers (EEF) to help reduce nitrogen losses from sugarcane. EEF is a catch all term for a number of products which fall broadly into two categories; namely coated fertilisers and nitrification inhibitors. Both reduce the availability of water soluble nitrate. The downside is EEF cost more than the conventional fertiliser nitrogen source, urea.

Surface runoff is driven by the annual wet season, which starts immediately after the sugarcane harvesting and fertilising ‘season’. For this reason, sugarcane fertilised late, closer to the start of the wet season, is particularly vulnerable to nitrogen losses. We hypothesised replacing urea fertiliser with an EEF for late season fertilising could reduce nitrogen lost from sugarcane in surface runoff water, without affecting sugarcane yield.

Here, we show EEF can reduce nitrogen losses from sugarcane in surface runoff and offer some insights as to the cost of those reductions. To facilitate broader adoption of EEF, some of these costs require mitigation, and we offer some thoughts on how that may occur.