F. Maghami Moghim, A. Karimi, Gh. Haghnia, A. Dourandish,
Volume 17, Issue 65 (fall 2013)
Abstract
The quantity and variability of soil organic carbon (SOC) is one of the most important indices to determine the effect of land use changes on the soil quality. Regarding long-term changes from rangeland to dry farming in the Roin area of North Khorasan, the objectives of this study were to investigate the effect of long-term land use changes on the SOC in different slope faces and use SOC as an index to make a proper decision about the future of land use in this area. 140 soil samples were taken from 0-15 cm soil depth of back slope position of north-, south-, west- and east-facing slopes of rangeland, dry farming, alfalfa dry farming and garden in 7 points. 14 soil samples were taken from irrigated farming, too. The results showed that garden and irrigation farming with averages of 2.03 and 0.78% have the maximum and minimum SOC content. The average of SOC content in rangeland was 1.40% that decreased by land use change to 1.04 and 1.27% in dry farming and alfalfa dry farming, respectively. SOC content in southern slope aspects showed a significant difference compared to other slope aspects. The most SOC content occurred in east aspects. It seems that after long-term land use changes, the SOC content have equilibrated to environmental and land use conditions. The average SOC content in different slope aspects except south one changed from 1.4% in rangeland to 1.11% in dry farming and 1.32% in alfalfa dry farming, which are a suitable value for semiarid regions. In conclusion, to protect land from degradation and considering this fact that dry farming is the main income of the people in the study area, it is recommended to stop dry farming on south aspects and continue on east, north and west aspects with conservation practices.
