Proximal sensor characterization of Haitian agricultural soils: A case study in the Central Plateau

Optimized agronomic production is vital to life and livelihood in Haiti. As such, rapid, low-cost soil characterization may inform specific decision making for improved crop production. Ahead of a larger soil characterization campaign (120,000 points) in Eastern Haiti, this study evaluated the use of two proximal sensors (portable X-ray fluorescence – pXRF; NixPro color sensor) at farms of Association Zanmi Agrikol (AZA) for soil characterization and evaluation of spatial variability of soil properties. Analysis of 166 surface soil samples (0–5 cm) collected in three different areas revealed that similar inter-elemental associations reported in other countries remain applicable in Haiti; weak, yet significant relationships between Al, K, and Fe contents and color parameters (L*, A*, B*) were observed. Considerable variability in soil morphology and chemical properties exist even across short distances, underscoring the need for high density sampling schemes. Soil pH (observed up to 8.4) likely imposes restrictions on the bioavailability of certain micronutrients; soil salinity was low (not agronomically limiting) across the study areas, and reflective of excessive drainage. Soil profile characterization identified one Eutrudept and one Quartzipsamment; both used for agronomic production. The proliferation of skeletal coarse fragments (e.g., cobbles, stones) and sandy matrix with depth emphasize the need for periodic supplemental irrigation and fertilization via either soil amendments (e.g., compost) or commercial fertilizers as water holding capacity and nutrient storage (e.g., clays, organic matter) are likely to be limited. Use of the NixPro color sensor showed differences in topsoil color likely reflective of differential soil organic carbon levels. The proximal sensors applied herein represent their first such use for agronomic management in Haiti and have shown considerable promise for additional study and application.