Irrigation with saline-sodic water: effects on two clay soils

摘要

The results of a4-year experiment aimed at evaluating the effect of irrigation with saline-sodic water on the soil are reported. The research was carried out at the Campus of the Agricultural Faculty of Bari University (Italy) on 2 clay soils (Bologna- Ti and Locorotondo - T2). The soils were cropped to boriotto bean (Phaseolus vulgaris L), capsicum (Capsicum annuum L), sunflower (Helianthus annuus L), wheat (Ttiticum durum Desf) grown in succession; the crops were irrigated with 9 saline-sodic types of water and subjected to two different leaching fractions (10% and 20% of the watering volume). The 9 solutions were obtained dissolving in de-ionised water weighted amounts of sodium chloride (NaCl) and calcium chloride (CaCfe), deriving from the combination of 3 saline concentrations and 3 sodicity levels. The crops were irrigated whenever the water lost by evapotranspiration from the soil contained in the pots was equal to 30% of the soil maximum available water. The results showed that, though the soils were leached during the watering period, they showed a high salt accumulation. Consequently, the saturated soil extract electrical conductivity increased from initial values of 0.65 and 0.68 dS nr1 to 1124 and 13.61 dS nr1 at the end of the experiment, for the soils Ti and T2, respectively. The saline concentration increase in irrigation water caused in both soils a progressive increase in exchangeable sodium, and a decrease in exchangeable calcium and non-significant variations in exchangeablepotassium (K) and magnesium (Mg).