Effect of Vegetation on soil Micromorphological Properties (Case Study: Karkaj research station)

Vegetation is one of the soil forming factors that its influences on soil micromorphological properties have been less attentioned. In this research to assess the effects of vegetation and its associated processes, five profiles with different covers including rapeseed, corn, alfalfa, apple and pine with a control profile were dug, described and sampled from all horizons in the countryside of Tabriz. Soil samples were physicochemically and micromorphologically analyzed after preparation. The results revealed the good pedality and structure improvement of surface horizons were in comparison with underlying ones. The order of soil pedality rate and degree of structure improvement for different covers were observed under apple, pine, corn, alfalfa, rapeseed and control profile (bare). Soil voids of surface horizons were found to be in packing void forms because of environmental effects. This is more obvious in farming vegetation than trees and bare because of application of several tillage instruments. Observation of excrement pedofeatures in the surface horizons and high abundance of them in the garden covers rather than forest and farming covers and bare land show the high biological activity in this vegetation. Presence of lime coatings refers to the role of plants and organisms through the production of CO2 and dissolution and sedimentary of carbonate in these soils. Presence of iron coating, nodules and iron-manganese oxides in some of the horizons is the evidence of oxidation and reduction processes in some horizons that according to the low water table and climatic condition, the reason can be found in the irrigation management.