Effects of irrigation with saline waters, at different concentrations, on soil physical and chemical characteristics

An irrigation experiment with saline water at different concentrations was carried out over a seven-year period on the same clay-loam soil in the Volturno Valley at Vitulazio to evaluate long -term effects of irrigation with saline water on crops and soil . The spatial distribution of the experimental treatments remained the same throughout the seven-year period in order to assess the effects of salt accumulation. Three saline concentrations of irrigation water (0.25-0.5 and 1% of NaCl) and two irrigation levels (100% and 40% restitution of evapotranspiration) were applied. The ECe was measured every year in spring before the irrigation season. Autumn-spring rainfall caused leaching of salts from the 0-0.4 m layer and an accumulation of salt in the deeper layers. Accumulation was directly correlated to the quantity of NaCl applied with irrigation. This allowed us to calculate, for the 0.4-1.1 m layer, the mean annual increase in ECe in (dS m-1 per t ha-1 year-1 of NaCl given). At the end of the experiment it was observed that there was an increase in ECe at a depth of 3 m for the saltiest treatments. The ESP, however, increased with the saline concentration of the irrigation water (quantity of NaCl) above all in the 0-0.4 m layer, and gradually decreased with depth. Irrigation with saline water led to an increase in ESP and a degradation of the soil physical properties that were estimated indirectly by measuring aggregate stability in water. The Index of Aggregate Stability in Water (IASW) for the top layer (0-0.15 m) was inversely correlated to the ESP values, even after the leaching due to the autumn-spring rainfall.