[en] Soil erodibility is one of six factors in the revised universal soil loss equation (RUSLE) that reflects the ease with which the soil is detached by splash during rainfall and/or by surface flow. This study was therefore carried out to assess applicability of the RUSLE model in estimating erodibility factor (K) and develop an appropriate equation to predict this factor in soils of the semi-arid region in Iran. Thirty six dry-farming lands were considered in a 900 km2 agricultural zone in Hashtroud, northwest of the country. Soil loss was measured at 108 unit plots under natural rainfall events for a 2-year period from March 2005 to March 2007. The K-factor was estimated using the mean geometric diameter of soil particles (Dg) and measured based on the mean annual soil loss per unit rainfall-runoff erosivity factor (R). Based on the results, the estimated K values varied from 0.0316 and 0.0485 t h MJ–1 mm–1 and the measured K values were ranged from 0.0014 to 0.0050 t h MJ–1 mm–1. The measured K values were almost 14 fold smaller than the estimated values on average. There was no considerable correlation between the measured K-factor and Dg (R2 = 0.05). Multi-regression analysis showed that the measured K-factor was significantly related to the aggregate stability and permeability (R2= 0.90, p &lt; 0.001). Although Dg was positively correlated with the soil permeability (R2 = 0.42), it did not strongly affect the measured K-factor (R2 = 0.05) because of its negative effect on aggregate stability (R2 = 0.64)

[es] La erosionabilidad del suelo, uno de los seis factores considerados en la ecuaci&oacute;n universal de p&eacute;rdida de suelos revisada (RUSLE), refleja la facilidad con que el suelo se desprende por la acci&oacute;n de la lluvia y/o del flujo superficial. Este estudio se realiz&oacute; para evaluar la aplicabilidad del modelo RUSLE en la estimaci&oacute;n de factor de erosionabilidad (K) y desarrollar una ecuaci&oacute;n apropiada para predecir este factor en suelos de la regi&oacute;n semi&aacute;rida de Ir&aacute;n. Se consideraron 36 fincas de secano en una zona agr&iacute;cola de 900 km2 en Hashtroud, al noroeste del pa&iacute;s. Se midi&oacute; durante 2 a&ntilde;os la p&eacute;rdida de suelo en 108 parcelas elementales en condiciones de lluvia natural, desde marzo de 2005 hasta marzo de 2007. Se estim&oacute; el factor K utilizando la media geom&eacute;trica del di&aacute;metro de las part&iacute;culas (Dg) basada en la p&eacute;rdida media anual de suelo por unidad del factor de erosividad lluvia-escorrent&iacute;a (R). Los valores de K estimados variaron entre 0,0316 y 0,0485 t h MJ&ndash;1 mm&ndash;1 mientras que los valores medidos de K variaron entre 0,0014 y 0,0050 t h MJ&ndash;1 mm&ndash;1. Los valores de K medidos fueron casi 14 veces menores de media que los valores estimados. No hab&iacute;a una correlaci&oacute;n considerable entre el factor K medido y el Dg (R2 = 0,05). Un an&aacute;lisis de regresi&oacute;n m&uacute;ltiple mostr&oacute; que el factor K medido estaba relacionado significativamente con la estabilidad y permeabilidad de los agregados (R2 = 0,90, p&lt;0,001). Aunque Dg estaba correlacionado positivamente con la permeabilidad del suelo (R2 = 0,42), no afect&oacute; aparentemente al factor K medido (R2 = 0,05), debido probablemente a su efecto negativo sobre la estabilidad de los agregados (R2 = 0,64).