Assessment of enhanced efficiency fertilisers in sugarcane grown in North Queensland

Abstract

The EEF60 project tested Enhanced Efficiency Fertilisers (EEFs) on 60 sugarcane farms located in the catchments of the Great Barrier Reef, over three cropping seasons. Four treatments including two urea and two EEF treatments were tested. One urea treatment had N applied at the industry standard SIX EASY STEPS (6ES) recommended rate (Urea 6ES), the three other treatments all received N at 20% lower than the 6ES rate. Applying urea at N rates 20% below 6ES decreased cane yield. Nitrification inhibitor (NI) coated urea and blends of 20% controlled release fertilisers (CRF) with 80% urea applied at N rates 20% less than 6ES maintained similar productivity and profitability to Urea 6ES. Applying an NI or CRF blended with urea at the 6ES N rate did not improve productivity and is likely to decrease profitability. NUE indicators, such as partial factor productivity of applied N and index for efficiency of fertiliser N recovery were improved when EEF’s were applied at N rates 20% less than 6ES. Findings indicated that NI and blends of 20% CRF with 80% urea at N rates 20% less than 6ES could be applied at any time during the season without loss of productivity or profitability. However, there was some evidence of better performance when loss conditions were likely to be high. EEFs appeared to obtain higher yields than Urea 6ES in some situations under high rainfall conditions. The concentration of DIN in leachate was shown to be higher in Urea 6ES compared to the lower N rate of urea and EEFs. Findings suggest that more widespread use of EEF’s at N rates 20% lower than 6ES would improve NUE without affecting productivity or profitability.