6.1. Field level surveys

In this section, we focus on the data that is collected at the level of the farm management unit (FMU).  We define an FMU as an area with a single crop (or crop combination) on which crop and field management activities (e.g. weeding, fertilizer application, irrigation) take place consistently over the season.  The aim of this definition is to ensure that the FMU can be looked at as a single entity in the images.  An FMU is fixed for the crop growing season; crop rotation methods or other practices, however, may blur that notion of season, and one crop’s season may merge into the next, so the definition has its weakness.  Between years or seasons, an FMU may be stable, i.e., remain spatially fixed, or not so.  Many factors (crop, soil, land rights, cultural, economic) influence that stability, and one cannot generally assume that an FMU in one year will be the same in the next year.  The questions of FMU stability (what and where) constitute a fairly open research area in themselves.

Four data categories to be collected can be distinguished.  Earlier work in context of JECAM is well-trespected and can provide inspiration how to set up one's work.  The notion of FMU is akin to that of annual cropland in JECAM’s Guidelines document.  A key characteristic is that within a full year, it is at least sowed or planted once, in contrast to permanent croplands.

  1. FMU characteristics,
  2. crop development information,
  3. farm management practices and
  4. biophysical characteristics.