Physical Deterioration of Semi-Arid Soils as Affected by Land Use Change in North West of Iran

Authors: Ali Reza Vaezi, Fereshteh Haghshenas

Abstract:

Land use has generally been considered a local environmental issue, but it is becoming a force of global importance. Extensive changes to forests and pastures are being driven by the need to provide food, fiber, and shelter for people in recent decades. Land use is an important factor affecting soil organic carbon accumulation and storage in soils which influence directly on other physicochemical soil properties, soil productivity and soil’s susceptibility to water erosion. The change of pastures to the agricultural lands has been increasing rapidly in most semi-arid regions in Iran. Information on the effect of the land use change in these areas on the deterioration of soil physicochemical properties is limited. Therefore, this study was conducted to investigate the physical deterioration of soil as affected by land use change in semi-arid pastures in north west of Iran. Toward this, seven areas covering both pasture and rainfed lands with different soil textures (clay loam, silty clay loam, sandy clay loam, silt loam, loam, sandy loam and sandy loam) were selected in a semi-arid region in Zanjan, NW Iran. Pasture in the area is covered with poor vegetation and mostly grazed in wet seasons (end of winter and early spring and autumn). Rainfed lands resulting land use change are mostly planted for winter wheat production. In each area, soil samples (0-30 cm depth) were collected from the two land uses (pasture and rainfed land) at three replications. A total of 42 soil samples were taken from the study area. Various soil physical properties consisting of bulk density, total porosity, coarse pores volume, aggregate size, aggregate stability, water-holding capacity and saturated hydraulic conductivity were determined in the soil samples using the laboratory conventional methods. The results showed that the change of pastures to rainfeds is severely deteriorated soil physical properties. However, the variation rate of the physical soil properties is different. The loss of soil physical properties as a result of the land use change was in the following order: 61% water-stable aggregates, 60% aggregate size > 41% macroporosity > 28% bulk density > 22% total porosity > 11% water holding capacity > 5% saturated point. This result reveals that the structural characteristics of soils in this area are the most important soil physical characteristics that are affected by land use change. The deterioration of these soil properties influences negatively the pore size distribution and volume percentage of macroporosity. Effects of land use change on deterioration of soil physical properties were different in various soil textures. The highest mean loss of soil physical properties was found in loam (42%), whereas the lowest value was in silty clay loam (23%). As a consequence, loam is the most vulnerable soil to physical degradation caused by land use change in the pastures. This physical loss of soil is associated with its higher percentage of larger aggregates as well as water-stable aggregates.

Keywords: Pasture, soil physical properties, soil structural characteristics, soil texture.

References:

[1] Ebabu, K., Tsunekawa, A., Haregeweyn, N., Adgo, E., Meshesha, D. T., Aklog, D., Yibeltal, M. 2020. Exploring the variability of soil properties as influenced by land use and management practices: A case study in the Upper Blue Nile basin, Ethiopia. Soil and Tillage Research, 200: 104614.
[2] Akinde, B. P., Olakayode, A. O., Oyedele, D. J., Tijani, F. O. 2020. Selected physical and chemical properties of soil under different agricultural land-use types in Ile-Ife, Nigeria. Heliyon, 6(9).
[3] Tadesse, L., Suryabhagavan, K. V., Sridhar, G., Legesse, G. 2017. Land use and land cover changes and soil erosion in Yezat Watershed, North Western Ethiopia. International soil and water conservation research, 5(2): 85-94.
[4] Santos, J. C. N. D., Andrade, E. M. D., Medeiros, P. H. A., Guerreiro, M. J. S., Palácio, H. A. D. Q. 2017. Land use impact on soil erosion at different scales in the Brazilian semi-arid1. Revista Ciência Agronômica, 48: 251-260.
[5] Datta, A., Basak, N., Chaudhari, S. K., Sharma, D. K. 2015. Soil properties and organic carbon distribution under different land uses in reclaimed sodic soils of North-West India. Geoderma Regional, 4: 134-146.
[6] Vaezi, A.R. and Bahrami, H.A., 2014. Relationship between soil productivity and erodibility in rainfed wheat lands in northwestern Iran. Journal of Agricultural Science and Technology, 16(6): 1455-1466.
[7] Obiahu, O. H., Kalu, A. I., Uchechukwu, N. 2020. Effect of tectona grandis biochar on soil quality enhancement and yield of cucumber (Cucumis Sativus L) in highlyweathered nitisol, Southeastern Nigeria. J. Wastes Biomass Manag (JWBM), 2(2): 41-48.
[8] Fu, A., C, Y., Sun, T., Li, F. 2021. Estimating the impact of land cover change on soil erosion using remote sensing and GIS Data by USLE model and scenario design. Scientific Programming, 2021: 1-10.
[9] de Sousa, G.P.B., Tayebi, M., Campos, L.R., Greschuk, L.T., Amorim, M.T.A., Rosas, J.T.F., de Oliveira Mello, F.A., Chen, S., Ayoubi, S. and Demattê, J.A., 2023. Improvement of spatial prediction of soil depth via earth observation. Catena, 223, p.106915.
[10] Hunke, P., Roller, R., Zeilhofer, P., Schröder, B., Mueller, E. N. 2015. Soil changes under different land uses in the Cerrado of Mato Grosso, Brazil. Geoderma Regional, 4: 31-43.
[11] Sadeghian, N., Vaezi, A. R., Majnooniheris, A., Cerdà, A. 2021. Soil physical degradation and rill detachment by raindrop impact in semi-arid region. Catena, 207, 105603.
[12] Celik, I. 2005. Land-use effects on organic matter and physical properties of soil in a southern Mediterranean highland of Turkey. Soil and Tillage research, 83(2): 270-277.
[13] Saha, D., Kukal, S. S. 2015. Land degradation and development, 26(3) 263-271.