Grower-driven on-farm experimentation to maximize nitrogen use-efficiency using precision agriculture

Innovative young growers from Isis (MR, NR) have begun to investigate nitrogen (N)-use strategies that would maximise productivity on their recently acquired farm. As part of their farm-improvement program, cane blocks were re-aligned, drainage was improved, and a new irrigation system was installed. It was decided to split N applications for ratoon crops as a means of improving productivity and N use-efficiency (NUE). A replicated strip trail was established on a 23-ha block of sugarcane cultivar Q240A commencing with the first ratoon. The aim was to compare application methods and N rates with previous fertiliser-management practices. An electromagnetic (EM) survey was conducted to better understand the variability across the trial site. This map was used as a tool to establish soil sampling sites and for further investigation of subsoil characteristics. SIX EASY STEPS nutrient-management guidelines were used to establish baseline nutrient requirements, from which the N rates were determined. The four fertiliser treatments were: ? Granular blend 154 kg N/ha, ? Granular blend 36 kg N/ ha and liquid 64 kg N/ha, ? Granular blend 36 kg N/ ha and liquid 94 kg N/ha, ? Granular blend 36 kg N/ ha and liquid 119 kg N/ha. Comparison of cane yield and CCS results indicated no significant differences among treatments in the first-ratoon crop. For this crop, NUE increased with decreasing N application rates. Further yield data from subsequent crops is required to fully understand the relationships between N rates and NUE for this site. The precision agriculture (PA) tools (EM map, yield map and variable rate application) that were utilised have helped to successfully gain a better understanding of block and yield variability. It is expected that this trial will continue for the next 2?3 crop cycles. This Grower Innovation project was made possible through a grant from the Reef Alliance Program, with additional support from Sugar Research Australia Limited, the University of Southern Queensland and Isis Productivity Limited. The Reef Trust Phase III: Reef Alliance ?Growing a Great Barrier Reef? project is a partnership between agricultural industry and regional NRM bodies and is facilitated by the Queensland Farmers? Federation (QFF), with a common goal of securing the future health of the Great Barrier Reef. The Reef Alliance Program is funded by the Australian Government Reef Trust.