Effect of Pistachio Residue and Salinity on Dynamic and Static Water Repellency of Three Texturally Different Calcareous Soils

Salinity and organic matter deficiency are the main problems of soils in arid and semi-arid regions. The use of residues in presence of salinity may affect soil properties differently. In this research, the effect of zero, 1. 5%, 3%, and 4. 5% application of pistachio residues and electrical conductivity (salinity) of water including three levels of 4, 8, and 12 dS m-1 were investigated on water repellency of soils with three different textures, namely, silty clay, loamy, and loamy sand. The static and dynamic water repellencies were determined by measuring soil-water contact angle and water penetration time. The mean values of soil-water contact angle for clay, loam, and sandy loam soils were 70±2. 5º, 65±2. 6º, and 62 ±3. 4º, and water droplet times (WDPT) were about 35±2. 6, 26±1. 6, and 18±0. 6 s, respectively. Accordingly, static water repellency of the fine textured soil was more than that of the medium and coarse textured soils by 3% and 7%, respectively, while the dynamic water repellency was 24% and 95% more, respectively. Salinity had no significant effect on static or dynamic water repellency. However, the salinity of 12 dS. m-1 increased the static water repellency of clay soil by 7%. The residues increased the static and dynamic water repellency of soils, except in silty clay soil where the effect of residues on static water repellency was not significant. In general, salinity levels had no significant effect on the mean values of the static and dynamic water repellency of soils; whereas application of residues (except for 4. 5% residues) increased both static and dynamic water repellency. Furthermore, since the applied residues were probably not fully decomposed in the time period used in this study, it is recommended that longer or different time periods be used in the future studies.