Information - Its Management and Importance
C.A. de Bie
International Institute of Aerospace Survey and Earth Sciences (ITC), Enschede, The Netherlands
At field level, basically, all that happens is of a Bio-physical nature. Soil, weather, crops, as management (operations, inputs etc.) all interact and define the performance of the land use system. This performance is measured by the objectives of the land user and are defined e.g. by the target benefits/yields, avoidance of production variability and negative trends and by conservation of the environment. These objectives are often clashing and not properly balanced.
Analysis of the performance of land use systems provides therefore the underlying foundation for further in depth planning studies at farm or regional level.
The performance is defined by both spatial as temporal aspects. Spatial aspects can be mapped if the most relevant system characteristics that define yield gaps between units and fields are known. Using these land characteristics, simulation results of water-limited crop growth models can be adjusted in an empirical way using the specified characteristics (land as management ~) as modifiers to derive at the factual yields levels by units.
Basic concepts and principles as required to collect and manage land use system data to carry out the yield gap analysis are explained. Several results of a range of studies are shown to illuminate the use of a yield gap study as input for extension, planning and monitoring.