The unstable areas along the right edge of the field are affected by a number of factors, such as the shading effect of the fence row, depressional areas that may pond and reduce yields and small knolls that may be prone to drought in some years. The large red zone occurred because the poor wheat yield caused the CV to become very large. The corn and soybean yields in this area are actually above average. In future years this red zone may disappear. One may also suspect that wheat yields will continue to yield poorly next time around.
Some investigation is required to determine why the wheat yield was so low.
This new yield map or management unit map now shows the long term spatial variability of yields within this particular field. However, for this map to be of use the causes for this spatial pattern need to be explained. Unless a cause can be attributed no management response can be determined. Yield mapping must be complemented with field investigation. The next question to consider is, do the three map units correlate with any soil, fertility or topographical characteristics of the field that would might provide us with some insight for the distribution of the management units within the field.