Variability within Irrigated Fields

In agricultural production and research, it is common to represent fields as uniform areas. For example, fertilizers, soil amendments, and other inputs have traditionally been applied uniformly (or as uniformly as possible) based on estimated needs for the field as a whole (or as an “average”). Of course, it is also recognized that fields are not truly uniform with respect to soil characteristics, uniformity of applied water, pest pressures, fertility needs, crop growth and yield, and other characteristics. With the emergence and refinement of variable rate application technology, many growers now attempt to maximize returns by “prescribing” variable amounts of inputs based on observations of crop vigor, soil characteristics, or other indicators. This technical note is intended to examine how we are using new sensing technology to improve the accuracy of field-scale irrigation/agronomy research