Evaluation of land use and suitability for rainfed crops in Roin, North Khorasan

Classification and utilization of lands based on their capability are necessary for sustainable land use management. The purpose of this study was to identify and grade the effective qualities on the rainfed farming in the Roin area, North Khorasan province, during the year of 2011. Based on field observations and literature review the land qualities including climate, rooting conditions, moisture availability, field workability and land degradation hazard were distinguished and rated as the most effective factors on the rainfed land suitability. To evaluate the land degradation hazard, the variations of soil organic carbon content in north-, south-, west- and east-facing slopes as a result of land use change was measured. In seven sites, 84 soil samples were taken from 0-15 cm soil depth of Back Slope with aspect of north- south- west- and east-facing slopes of rangeland, wheat dry farming and alfalfa dry farming. In addition, 21 soil samples were taken from nearly flat areas (Toe slopes and back slopes) of studied land uses. The results indicated that all aspects except the south-face slopes the amount of soil organic carbon suitable for semiarid regions. In the study area, the climate and qualities related to soil, have no limitations for dry farming. Only field workability and land degradation hazard qualities which are affected by slope and slope aspect are main limitation factors. Based on results the slopes more than 20% and the southern slopes were identified non-suitable for dry farming but the southern slopes were partly suitable for alfalfa dry farming. Considering the mentioned limitations, the areas under dry farming cultivation will be decreased from 1186 to 942 ha. More investigation for new land utilization types is necessary to compensate the negative economic consequences of cultivation land reduction.