Identifying potential within-field management zones from cotton-yield estimates

Remotely-sensed cotton yield estimates, collected mid-season over the past 11 years, were investigated to identify the degree of temporal stability exhibited in two irrigated fields on "Colly Central" farm, Collarenabri, NSW, Australia. In particular, the aims of the investigation were: (1) to develop stable yield zones from multi-year yield estimates derived from 11 consecutive years' mid-season Landsat TM imagery; (2) to discover the number of consecutive years of yield estimates required to give similar "stable" estimates of yield zones to those derived from all 11 years of available data. Results of the investigation indicate that the fields described in the study exhibit a strong degree of temporal stability. Additionally, where an assumption is made that 11 years worth of yield estimates will cluster to generate the most temporally stable "regions of similarity," the mapping of clusters generated using 5 or more years will generate comparable "regions of similarity" with high confidence that the regions will indeed closely match those of the temporally stable 11 year estimates.