Electromagnetic induction as a basis for soil salinity monitoring within a Mediterranean irrigation district

Abstract

Soil salinity encroachment is an increasing concern in many irrigated lands, because of the undesirable effects of soluble salts on agricultural production and on water quality. From this point of 10 view, the design and management of irrigation districts can be evaluated by monitoring the soil salinity.There are few cases in the world where comparisons can be undertaken from 'historic' data sets for extents other than individual plots. We demonstrate a monitoring procedure using electromagnetic induction (EMI) survey in an irrigated district in Spain. This district is the only one having an established soil salinity baseline. The EMI data acquired at the same plots were converted to soil 15 electrical conductivity by calibrating with augered soil samples. The presented calibrations improve the baseline for future comparisons and for the treatment and understanding of new acquisitions of field data in next surveys. A shortcoming inherent to destructive soil sampling is its potential for biasing effects on long-term monitoring of soil salinity by means of GPS or other means of accurate localization and relocalization of soil sampling, the herein called "localization paradox", rarely treated 20 in scientific papers. The localization paradox is relevant for any variable soil property requiring repeated sampling. This issue is discussed, and a way for its overcoming by using EMI readings displaced from the augering is presented. EMI needs calibration with a reduced number of soil samples analyzed in the lab. The adoption of our data treatment procedures will facilitate soil salinity monitoring. 25

Accuracy and uncertainty assessment on geostatistical simulation of soil salinity in a coastal farmland using auxiliary variable

“…This yielded seven predictive regression equations across the whole soil profile (Table 1). Readers are referred to Sudduth et al (2001), (2005), Harvey and Morgan (2009) and Herrero et al (2011) for detailed descriptions of similar approaches.…”

“…This is particularly the case in coastal farming areas where soil salinization is the most frequently cited agricultural and environmental degradation problem for farmers (Haque 2006;Abdelfattah et al 2009). Electromagnetic induction instruments (e.g., Geonics Ltd. EM38), which measure apparent soil electrical conductivity in a fairly quick manner, have been widely used to provide information on the nature, origin, interpretation, and assessment of soil salinity (Corwin and Lesch 2005;Yao and Yang 2010;Herrero et al 2011). However, soil salinity at the field can have high spatial heterogeneity.…”

GIS-mapping spatial distribution of soil salinity for Eco-restoring the Yellow River Delta in combination with Electromagnetic Induction

“…It is important to monitor soil salinity in an effort to manage the irrigated land well. Herrero et al (2011) conducted a survey with EMI system to get the detailed baseline data for soil salinity in Flumen irrigation district where the land had been irrigated more than 50 years, showing that the EMI system was suitable to evaluate soil salinity in irrigated areas. The information of ECa survey is used for mapping spatial variability of soil properties that are invaluable in ecosyetem and agriculture for assessing soil quality, planning land use, and determining the suitability of cropping patterns Corwin and Lesch, 2005;Yao et al, 2007;Urdanoz and Araguees, 2011).…”

Temporal changes in soil salinity at four saline wetlands in NE Spain

“…Overall, 404 soil samples were collected at 12 sampling sites, 386 samples from 52 auger holes (mean sampling depth = 105 cm), and 18 samples from four pits. At each site, the augerings that were repeated were within 2 m of the remains of the initial pit or auger hole, an acceptable distance for measuring temporal changes in soil salinity (Herrero et al, 2011). Herrero and Castañeda (2013) provide details about the sampling sites and dates, validated the analyses, and discussed the results.…”