Abstract
Soil salinity is a major threat in irrigated agriculture because of its negative on-site (decreased productivity) and off-site (salinization of irrigation return flows) effects. The delineation of the spatial variability of soil salinity is best suited using non-invasive geophysical measurements of the apparent soil electrical conductivity (ECa) using mobile GPS-based systems. Two simple and cost-effective Mobile Georeferenced Electromagnetic Sensors (MGES) developed in Aragón and Navarra (Spain) are described. These devices involve electromagnetic instruments towed by all terrain vehicles and combined with GPS units and data acquisition systems that collect both ECa readings and GPS coordinates. Two applications of the MGES aimed at delineating ECa maps for (1) selecting the most suitable crops in a 43-ha saline site (Hondo de Espartosa) and (2) correlating ECa with drainage water salinity to ascertain the salinity-source areas in a new 715 ha irrigated basin (Barranco de Lerma) were examined. These examples demonstrate the MGES surveying capacities for management of salt-affected agricultural areas.
Highlights
Soil salinity reduces soil and water quality, constrains crop yield and agricultural productivity, and, in severe cases, leads to the abandonment of agricultural soils
32 and 45 million are soils cultivated under dry land and irrigated agriculture, respectively
Soil salinization has been identified by the European Commission as one of the eight major threats to European soils, mainly in the Mediterranean area (EC, 2003), and Herrero and Aragüés (1988) indicated that about 25% of the irrigated land in the Middle Ebro basin of Spain is salt-affected
Summary
Soil salinity reduces soil and water quality, constrains crop yield and agricultural productivity, and, in severe cases, leads to the abandonment of agricultural soils. According to FAO, the total global area of salt-affected soils is 831 million hectares (Martínez-Beltran and Manzur, 2005). From this total, 32 and 45 million are soils cultivated under dry land and irrigated agriculture, respectively. Secondary salinization is a relevant threat in irrigated agriculture. FAO (2002) estimates that 0.25 to 0.5 million hectares of irrigated land are salinized yearly. Soil salinization has been identified by the European Commission as one of the eight major threats to European soils, mainly in the Mediterranean area (EC, 2003), and Herrero and Aragüés (1988) indicated that about 25% of the irrigated land in the Middle Ebro basin of Spain is salt-affected
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