Using an objective and probabilistic model to delineate homogeneous zones in hedgerow olive orchards

Abstract

The first stage to implement site-specific crop management (SSCM) within an agricultural field consists in determining subfields of similar production potential, that is, management zones (MZ). Different approaches have been proposed to delineate MZ, but sometimes results are inaccurate and unsatisfactory. In this study, the formulation of the Rasch measurement model, as an objective method which synthesizes data with different units into a uniform analytical framework, is considered to calculate measures of production potential at some locations of an olive orchard. Later, they can be used to delimit MZ.With the aim of illustrating this approach, nine soil properties (soil apparent electrical conductivity, clay, sand, and silt content, organic matter, total nitrogen, available phosphorous and potassium, and cation exchange capacity) measured from soil samples taken at 40 locations in a field were considered. The main results, after applying the Rasch model, were a ranking of all locations according to the soil production potential and another one in which the influence on the production potential of each individual soil property is shown. Moreover, those soil samples or properties which have any anomaly where highlighted; this information can be necessary to conduct site-specific treatments, leading to a more cost-effective and sustainable field management. Additionally, estimates using geostatistical algorithms were utilised to map soil production potential and to delineate with a rational basis the MZ in the field.