Grid sampling of soil is used to formulate digital prescription maps for fertilizer requirements, and these maps are used for computer control of variable rate fertilizer applicators. However, some research has shown poor correlation between initial soil nitrogen and final yield. Previous work has demonstrated the potential of in-season indicators in predicting crop yield before harvest. Potential in-season indicators include soil nitrogen and water status, weed pressure, plant disease, plant physiological traits and canopy reflectance measured either on the ground with a hand held instrument or remotely with aerial imagery. This early yield estimation would both compliment data from a combine yield monitor and aid in planning remedial strategies.
Additional work is required to identify and develop the most useful in-season indicators.
Ideally, the sensors could be mounted on field machinery and data collected in conjunction with a normal field operation. Data from each type of sensor can be geo-referenced by simultaneously logging GPS data and maps of the respective attribute, mapped similar to the familiar combine yield map. The ability to collect large amounts of spatial data has or will undoubtedly lead to information overload. Mapping programs do some filtering but there does not appear to be any standard. Development and assessment of appropriate filtering algorithms is required to separate the small scale noise from the larger scale variability which can be managed.