Impact of an alternative system on some soil properties as compare with forest and cropland systems

Background and objectives: Farmers have lead to the land use change of natural systems, because of excessive population growth, followed by increasing demand of food. It has led to land degradation and economic, ecologic problems. Land use change is considered as a major environmental change in the world and destroy natural and native vegetation, degrade soil and reduce its nutrients that followed by economic and ecological problems. Due to limited water and soil resources, efficient use of land, more than ever, is taking into consideration. An alternative to improve soil quality of degraded lands is the establishment of new forestry plantations, agro forestry, and orchard systems. These alternative systems improve residues availability; nutrient cycling, soil permeability and erosion control in the ecosystem of degraded lands and increase their biodiversity. The aim of this study was to investigate the effects of olive plantation, as an alternative system, on some soil properties and its erodability compared with forest (natural and artificial) and agriculture systems in south of Azadshahr.
Materials and methods: The study area located at 55° 10´ 26" ´ longitude and 37° 4´ 12" latitude. Its mean annual temperature and annual relative humidity are 18.4ºC and 68%, respectively. Its climate is temperate semi-humid with the mean annual precipitation of 475 mm. Boundaries of the studied treatments (Olive orchards, Natural forest, Artificial forest, and Croplands) were accurately determined using Google Earth software and field survey. then in each systems, five composite soil samples were taken at the depth of 0– 20 cm. Once in the laboratory, some soil physical and chemical characteristics such as soil texture, aggregate stability, bulky density, porosity, pH, EC,percentage of organic matter, total nitrogen, lime, the amount of cation exchange capacity, absorbable phosphorous, exchangeable potassium, calcium, and magnesium were measured and soil C/N ratio and its erodibility index was calculated by using the modified clay ratio relation. Data analysis was performed by using one-way ANOVA. Tukey’s test was used to perform pairwise comparisons.
Results: The results demonstrated that establishment of olive orchards in croplands, have not had significant positive effect on soil physical properties, but soil chemical properties such as pH , EC, percentage of organic matter, total nitrogen, and the amount of cation exchange capacity have been increased significantly. Soil erodability index has been decreased either.
Conclusion: According to the obtained results and with regard to high limitation of the soil in the study area in terms of soil aggregate stability, it is recommended that it must be prevent of change of the remaining natural forest lands into croplands. In the study area, construction of olive orchards is preferable as compared with artificial forest and croplands, either.