Effect of Organic Matter Application on some Soil Physical Properties under Saline Conditions

Soil salinization and sodification are important factors in soil degradation, especially in arid and semi-arid regions, which, if not considered, can lead to erosion that threatens soil stability in different regions of watersheds. Effects of organic matter application on some soil physical properties under irrigation with saline waters was investigated. The experiment was conducted as factorial based on complete randomized design with three replications for a period of one year. Treatments included two levels of irrigation water salinities of 7 and 14 dS/m, two soil textures, namely sandy loam and clay loam, and four sources of organic matters, namely licorice and lemon dregs and chicken and sheep manure. Results showed that organic matter had a significant effect on moisture retention and evaporation from the soil surface (P <0.01) and reduction of soil bulk density (p < 0.05). The percent moisture content of the loamy sandy soils treated with licorice and lemon dregs and chicken and sheep manure increased by 25, 20, 15 and 15%, respectively. The lowest evaporation from the soil columns occurred in licorice treatment amounting to 39.99 cm, which was 8% lower compared to evaporation from the control treatment (43.26 cm). This decrease was statistically significant at the 5% level with the Duncan's test. The results also showed a significant effect of soil texture on soil moisture content at lower depths (P <0.01). Regarding the prominent role of licorice treatment in reducing evaporation from the surface and maintaining soil moisture, further studies are suggested on the feasibility of applying the results in soil and water conservation programs, especially on sloping lands.