Effects of Different Mulching Materials on Soil Salinity of a Semi-Arid Drip-Irrigated Nectarine Orchard

The effectiveness of inorganic (plastic) and organic (geotextile and pine bark) mulching materials for soil salinity control as compared to the bare soil was assessed during three years in a semi-arid, drip-irrigated nectarine orchard. The soil solution electrical conductivity (ECss) was measured in 3174 samples regularly extracted with suction cups at two soil depths (20 and 40 cm) and three sampling positions (EM-emitter, EL-emitter line, and TR-tree row) during the 2010–2012 irrigation seasons. Considering all treatments, ECss increased (p < .05) with distance to emitters, both vertically (mean ECss = 4.7 dS m−1 at 20 cm and 6.3 dS m−1 at 40 cm soil depths) and horizontally (mean ECss (20 + 40 cm soil depth) = 2.9 dS m−1 at EM, 4.4 dS m−1 at EL, and 9.1 dS m−1 at TR). The monthly changes in ECss were negatively correlated (p < .01) with the monthly field-wide leaching fraction estimates. Based on the 2010–2012 mean ECss values, the effectiveness for soil salinity control of the examined treatments was (p = .05): plastic (4.2 dS m−1) = pine bark (4.6 dS m−1) < bare soil (5.8 dS m−1) = geotextile (5.9 dS m−1). Overall, due to their lower soil water evaporation rates, the plastic and pine bark materials were best suited for soil salinity control under the prevailing climatic characteristics in the study area.