Micro- and macrostructure changes of soil under irrigation with electromagnetically treated water

Abstract Electromagnetic treatment of irrigation water (ETIW) for agricultural purposes is increasingly studied, especially for saline water, but little is known about its effect on soil structure. The aim of this study was to quantify pore changes due to ETIW applied to a cultivated soil. The study was performed on undisturbed soil in pots subject to 12 treatments: two types of irrigation water (treated electromagnetically or untreated) × three irrigation doses × two cultivation statuses (cultivated or uncultivated). The structure of soil samples taken from the surface layer at the end of the experiment was studied by impregnating it with a fluorescent resin and examining horizontal polished sections. Images were analyzed using Visilog software at two spatial resolutions (micro- and macromorphological) to quantify pores classified according to size and shape at each scale. No significant difference in porosity was found among depths, regardless of scale. Soil porosity increased slightly as the irrigation dose increased. Cultivation had no significant effect on porosity at either scale. In contrast, ETIW had a strong effect on porosity, which, on average among depths, increased from 8.8–11.4 % to 11.9–14.8 % at the macroscopic scale and from 13.1–14.2 % to 20.6–22.7 % at the microscopic scale. At the macroscopic scale, pores of all morphological types increased after ETIW. At the microscopic scale, packing pores increased the most after ETIW, while cracks and tubular voids changed the least. Our results suggest that ETIW thus acts on soil structure by fragmenting soil material at a fine scale and creating abundant interstitial porosity between aggregates by crumbling. ETIW can improve soil properties greatly by increasing soil porosity at two scales. Through this porosity, water, solutes and gases can diffuse through the ground, thus increasing exchange processes.