Comparison of The Effect of Cow Manure, Vermicompost and Azolla on the Chemical and Hydraulic Properties of Saline-Sodic Soil

Salinity and sodimization of soils are two factors of land degradation, especially in arid and semi-arid regions of the world. Iran is also located in an arid and semi-arid region, and saline-sodic soils cover large areas of Iran. Considering that saline-sodic soils have poor physical, chemical and biological properties that reduce the absorption of nutrients by plants and eventually decline in their growth and yield. The use of reformers, including organic matter, can often be a suitable solution for improving the fertility of saline-sodic soils. In this study, saline-sodic soil was collected from Nazar-Abad area of Karaj and was mixed with three levels of 1, 3 and 5 percent of cow manure, vermicompost and Azolla (as Organic modifier). Then the treatments were incubated for 5 months at 20 ° C temprature and field capacity moisture. The chemical and physical properties of the control soil, fertilizers and some chemical and hydraulic properties of the treatments were evaluated before and after incubation. The electrical conductivity of the control soil was 13.09 dS / m and its sodium absorption ratio was 23.02. After incubation period, 5% Azolla and Vermicompost treatment are at the lowest salinity level. pH reductions in treatments were mostly non-significant. The highest range of changes in the sodium absorption ratio was related to 5% cow manure treatments with a significant difference relative to all treatments. Except for saturated moisture content, there was no significant difference in the amount of moisture in a given suction in different treatments. During the incubation period, there is a significant decrease in the total amount of porosity in all treatments. This decrease was significant in mean porosity in all treatments, the most significant decrease was observed in 5% cow manure treatment, and however 5% vermicompost treatment had the highest mean porosity (It should be noted that most of the water available to plants is in the mean porosity). After incubation period, salinity and pH reduction and increasing of sodium absorption ratio were observed in most treatments. On the other hand, it reduced the coarse and mean porosity, resulting in a decrease in the saturation hydraulic conductivity in the treatments. According to the findings of this study, Vermicompost fertilizer at the level of 5%, with chemical and hydraulic correction of saline-sodic soil, showed its superiority among these three fertilizers, and then the Azolla at the level of 3% is given priority.