Abstract: In this study, the spatial patterns of dry matter (DM) yield in a grass silage field at first, second and third cuts over a three-year period were evaluated, and temporal variability of sward at the first and the second cut was quantified and classified management maps for DM yield were produced for these two cuts. Unfortunately, the absence of third cut data in 2001 meant that an analysis of temporal stability could not be made on the yield patterns for this late season crop. A 7.9 hm² grassland field close to the Agricultural Research Institute at Hillsborough, Northern Ireland, was selected for the study. At cut 1, the spatial patterns of DM proved to be well defined and temporally stable. In contrast, at cut 2, the patterns of DM production were patchy and temporally unstable. It was concluded that site-specific management approach to fertilization according to the classified management map, in spring, ought to be feasible. At later harvests, site-specific management approach to fertilizer management was difficult.