Yield Map Interpretation: A Need for a System Approach.

The objective of this study was to understand the spatial and temporal variability of wheat yield in a field in Southern Italy.  Field measurements on soil and crop variables were taken over space (100 georeferenced points) and time (5 years), along with Electrical Resistivity Tomagraphy and remote sensing imagery from various platform (handheld hyperspectral radiometers, airborne images and satellite.  Vegetation indices were used to monitor the in-season performance of the wheat crop. Spatial analysis of crop yield allowed for the selection of three management zone which were highly depended on soil properties and position in the landscape.  Correlation matrix between rainfall and yield clearly illustrated the impact of rainfall on yield variability.  A system approach was used to assess the long term impact of weather on previously identified management zones.  The model was used to select the best N management for three zones. Three different N rates were imposed on the field during the year 4 and 5 of the research.  The effects of N rate on yield spatial variability were determined.  Rainfall distribution and plant N availability were important factors influencing the final yield in this field. The integration of the technologies used was proven to be useful in quantifying spatial and temporal patterns of wheat yield in Mediterranean environments.