IS DISTRICT YIELD POTENTIAL AN APPROPRIATE CONCEPT FOR FERTILISER DECISION MAKING?

POTENTIAL YIELD IS one of the criteria used as an input to nitrogen (N) fertiliser management decisions made using SIX EASY STEPS (6ES). While it is recognised that 6ES allows the estimate of potential yield to be made at whatever scale is deemed appropriate (block, farm, region, etc.), the fact is that 6ES is generally implemented using a district yield potential (DYP). However, the gradual adoption of Precision Agriculture (PA) technologies, such as remote sensing and yield monitors, along with mill records of yield at the block and farm scale, suggests that yield varies markedly within regions. This raises questions as to the merits of using DYP as an input to 6ES. This paper presents a spatial analysis of yield variation in the Herbert River district over 7 seasons using mill records. The results suggest that there is a marked spatial variability in yield in the Herbert River district, and that the patterns of this variation are stable across seasons and crop class. They therefore provide a basis for moving away from the use of DYP as input to 6ES and, for those Herbert growers who have not yet adopted PA for the fine-tuning of fertiliser management at the within-block or -farm scales, a basis for a more location-specific application of 6ES. A similar analysis could be readily conducted in other sugarcane growing regions, while examination of spatial variation in the other factors underpinning 6ES may also be valuable.