Assessment of the soil structure stability focusing on the high-energy moisture characteristic curve in pasture and arable land uses in semi-arid areas, northeastern Iran

Abstract

A b s t r a c t. Investigating the effects of land use on soil structure in order to prevent the ever-increasing risks of soil degradation is important. The objective of this study was to compare the stability of soil structure using different methods in pasture and arable land uses in northeastern Iran. Soil samples were collected from a depth of 0-20 cm at two sites including pasture and arable land uses. Soil structure stability was determined using tensile strength, soil friability and Dexter's number by focusing on the high-energy moisture characteristic curve procedure. The results showed that there were significant differences between the values of modal suction (p < 0.05), volume drainable pores, structural index and stability ratio, the aggregate stability index of the high-energy moisture characteristic curve method (p < 0.01), and Dexter's number (p < 0.01) in pasture and arable land uses. In addition, the difference (p < 0.01) between the values of particulate organic matter in both land uses was significant. In arable land use, stability ratio, particulate organic matter and clay were found to be 10.9, 41.7, and 4.9% less than in pasture land use, respectively, and Dexter's number was found to be 63.1% more than in pasture land use. Considering that the value of stability ratio in pasture land use (0.5345) was significantly greater than that in arable land use (0.4761) and the value of Dexter's in arable land use (122.68) was significantly greater than that in pasture land use (75.20), it may be concluded that the stability of the soil structure in pasture land use is greater than that in arable land use. Also, according to the results obtained, it may be asserted that the high-energy moisture characteristic curve method and Dexter's number are suitable methods for the evaluation of the stability of the soil structure in lands with similar characteristics to those of the study area used in this research.