ABSTRACT
Site-specific crop management is concerned with adapting management to the variation of the crop-growing environment. For most applications and research (see Chapters 4 and 12, for example) the focus has been on the spatial variation of the crop-growing environment, for example different soil types may be present across a field. Each of these soil types may have different nutrient- and water-holding capacities, different yield expectations and therefore require different agronomic inputs. However, variation in time can be equally important for properties such as soil moisture, crop nutrient status and soil available nutrients. For example, the different soil types will, as a result of their different water-holding capacities, respond differently to rainfall or irrigation in terms of soil moisture and nutrient cycling, and ultimately yield (Lark et al., 1998). Therefore, not only is it important to understand the spatial variation within fields, it is equally important to understand the temporal variation to achieve more precise management of the crop-growing environment.
