Definition of homogeneous management zones (HMZ) in pastures based on soil apparent electrical conductivity survey: Case study in the Montado Mediterranean ecosystem

Abstract

The Montado (in Portuguese) or Dehesa (in Spanish) Mediterranean ecosystem consist of soils with low fertility, a sparse cover of cork and holm with an understory of natural biodiverse pastures, grazed by animals. The possibility of intensifying this silvo-pastoral ecosystem, with an associated increase in pasture productivity and extensive animal production, involves the use of technologies to monitor spatial variability and to implement differentiated management of fertilization and soil amendment. An intermediate step consists in the identification and demarcation of areas with similar characteristics (soil and/or crop development), known as homogeneous management zones (HMZ) which is required for implementing site-specific management strategies. In this study, soil electrical conductivity (ECa) survey was carried out at three experimental fields with a non-contact electromagnetic induction sensor (EM38). These ECa and topographic maps (obtained by a GPS sensor) were used in geostatistical anlyses for designing and establishing final classified maps with three HMZ (low, intermediate and high production potential). From a practical perspective, these three HMZ are the basis for smart soil sampling, preparation of fertilizer prescription maps and use of variable rate technology (VRT) in a Precision Agriculture project.