Influence of Salinity and Sodicity on Soil Structural and Hydraulic Characteristics

Abstract

An exchangeable sodium percentage (ESP) >15 is traditionally considered to affect soil structural and hydraulic characteristics. Recent investigations show that both this critical value and the concept of critical threshold need reconsideration, because soil degradation often takes place even at lower ESP in dilute solutions, and soil behavior at increasing ESP appears to be a continuum. This study was carried out to analyze the response of two Sicilian Typic Haploxererts to ESP values up to 15, at a low cationic concentration. The investigation was carried out on aggregate stability, rating of soil shrink‐swell potential, and both saturated and unsaturated hydraulic conductivity. The specific purpose was to verify if a critical ESP threshold exists, or if the hypothesis of a continuum behavior is more appropriate. The high‐energy moisture characteristic technique was used for determining aggregate stability, and Brasher's method for the shrinkage characteristic. The constant‐head method was used for determining saturated hydraulic conductivity, and the parameter estimation method based on one‐step outflow experiments for unsaturated hydraulic conductivity. Almost linear relationships were found between the investigated soil properties and ESP, indicating no critical ESP threshold; furthermore, the results obtained indicate that an effective hazard of soil quality degradation can be forecast even in a 2 to 5 ESP range at a low cationic concentration. This is a basic indication for irrigation management aimed to combat and prevent degradation of soil quality.

Sewage Sludge Amendment Combined with Green Manuring to a Coastal Mudflat Salt-Soil in Eastern China: Effects on Soil Physicochemical Properties and Maize Yield

“…In the present study, statistical analysis also showed a significant negative correlation between soil ESP values and soil aggregate stability percentage in topsoil ( < 0.01) (Figure 6(d)). The similar negative effects of ESP on soil aggregation were found by other studies [45][46][47]. This might be attributed to that sodium causes swelling and dispersion of soil mineral particles and slaking of unstable aggregates [45,48].…”

“…The similar negative effects of ESP on soil aggregation were found by other studies [45][46][47]. This might be attributed to that sodium causes swelling and dispersion of soil mineral particles and slaking of unstable aggregates [45,48]. In addition, high ESP value can reduce microbial biomass and activity, which may also contribute to the decrease in aggregation [49].…”

Field and laboratory approaches for determining sodicity effects on saturated soil hydraulic conductivity

“…This can in turn decrease soil hydraulic conductivity through the reduction of soil structure and the plugging of soil pores by dispersed clay particles (Abu-Sharar et al, 1987;Yousaf et al, 1987;So and Aylmore, 1993). The slaking-dispersion process can be greatly enhanced when the cationic concentration of the antecedent soil pore water is diluted by infiltrating rainfall and/or low-sodium irrigation water (Frenkel et al, 1978;Crescimanno et al, 1995). In addition, sodium-induced slaking and clay dispersion can be particularly destructive at the soil surface as it may cause the formation of a virtually impermeable surface crust that both impedes water entry into the soil (Agassi et al, 1985;Shainberg et al, 1992) and impairs seedling emergence (Hausenbuiller, 1978).…”

Amelioration of a saline sodic soil through cultivation of a salt-tolerant grass Leptochloa fusca

“…Salt-affected lands can be effectively used and ameliorated through judicious use of various plant species (Chaudhry et al 1985;Robbins 1986;Chang et al 1994;Crescimanno et al 1995). The amounts of Cl Ϫ , SO 4 2Ϫ and HCO 3 Ϫ in soil solution also decreased exponentially as a result of kallar grass growth.…”