Toposequence and Land use Effects on Some of Soil Physical, Chemical and Clay Mineralogical Properties (A Case study: Chaypareh, West Azarbayjan Province)

For proper management of soil, conducting a comprehensive assessment seems necessary and basic. Soil forming processes strongly vary among different land uses and topographies. In this study, a factorial experiment was performed in a completely randomized design with 2 factors (type of land use and soil depth) in 3 replications, in order to investigate the impacts of topography and different land uses on soil physical, chemical and mineralogical properties of soils of Chaypare, West Azerbaijan province, Iran. There were three dominant land uses including pasture (low density of vegetation cover), dry farming (mainly wheat without annual alternating crops) and irrigated farming (with annual alternating crops). In the present study, two soil profiles were dug for each land use and then clay mineralogy, along with the physico-chemical properties, were determined. The results indicated that changes in the both topography and land use influenced the soil cation exchange capacity (CEC) through affecting both the clay and soil organic matter contents. Although, there were no significant differences in physic-chemical properties among different land uses, the soils of irrigated farming showed relatively lower amounts of calcium carbonate equivalent (CCE) and sand content than the two other land uses and the amounts of organic matter content and CCE and pH were considerably dominant in the irrigated farming. The X-ray diffraction (XRD) measurements indicated that both the topography and type of land use had no significant effect on the qualitative properties of the clay minerals but they were effective on their semi-quantitative properties. Accordingly, the amount of smectite in the fine clay fraction in the irrigated farming was dominantly higher than that of the other land uses. Additionally, the status of the different cultivated crops seemed to affect the quantity of clay minerals in the both dry and irrigated farming land uses. Finally, the irrigated farming compared with the two other land uses (pasture and dry farming), revealed to be more affected by the slope and pedogenic processes.