Document Type : Research Paper


1 PhD Student, Department of Soil Science, College of Agriculture, Isfahan University of Technology, Iran

2 Department of Soil Science, College of Agriculture, Isfahan University of Technology, Isfahan , Iran

3 Department of Soil Science, College of Agriculture, Isfahan University of Technology, Isfahan, Iran

4 Soil Science Department, University of Tehran


Introduction Soil erosion is one of the major obstacles to sustainable development. A large part of Iran has an arid and semi-arid climate, without vegetation with suitable density or even completely without vegetation. Therefore, many parts of the country face high erosion and soil losses. Previous studies showed an increased trend of soil erosion in Iran. Because in situ measurement of soil erosion at the farm or watershed scale is expensive and time-consuming, estimation of soil erosion from easy and ready parameters can be useful. It is well-known that aggregate stability can affect soil erosion. There are many methods developed to measure soil aggregate stability, but there is no specific method that can be used for a wide range of soil types under different land uses. This study was done to compare different methods of aggregate stability determination (i.e., splash rate measurement, shear strength measured with fall-cone penetrometer and wet sieving).
Materials and Methods Twenty-eight soil samples with different textures, equivalent calcium carbonate, and organic matter were collected from surface soil layers in Isfahan and Chaharmahal-va-Bakhtiari provinces. Particles size distribution of studied the soil was measured. Very coarse sand (VCS), coarse sand (CS), medium sand (MS), fine sand (FS) and very fine sand (VFS) were measured according to ASTM sieves. Also, four components of silt (0.035-0.05, 0.02-0.035, 0.01-0.02 and 0.002-0.01 mm) were measured according to Stock's law by the pipette method. Geometric mean diameter and geometric standard deviation of particles were calculated by Shirazi and Boeresma (1984) relations. Soil splash rate (S) was measured with rainfall simulator, near-saturated soil shear strength (τ) was determined using the fall-cone penetrometer, and mean weight diameter (MWD) and geometric mean diameter (GMD) of soil aggregates were measured by the wet sieving.
Results and Discussion The results of this study showed that the sand, silt and clay contents were, respectively, in the ranges of 1.5-51%, 34-73% and 11-35% in the studied soils. Most of the sand particles belonged to the FS and VFS (0.05-0.25 mm) fractions and most of the silt fraction was in the very fine silt (0.002-0.01 mm) fraction. The range of organic matter was 0.08 to 8.8% and calcium carbonate equivalent varied in the range between 10% and 63%.
Generally, soil aggregate stability was low and splash erosion was high in the studied soils. The results showed that S showed significant correlations with sand, silt, and geometric mean diameter and geometric standard deviation calculated using all particle fractions, VCS, CS, MS, FS, fine silt and very fine silt. Soil shear strength (τ) had significant correlations with silt, very fine silt, geometric mean diameter and geometric standard deviation. The GMD and MWD had significant correlations with soil organic carbon. The results showed that S had significant and negative correlations with τ and GMD, and there were significant and positive correlations between τ with GMD and MWD. The S was mainly dependent on particle size distribution, while GMD and MWD mainly depended on soil organic carbon. However, both particle size distribution and soil organic carbon would affect τ. This finding might be justified by differences between mechanisms which are responsible for particles detachment. The energies induced by raindrop impact and slaking are the main forces and mechanisms responsible for detachment of particles in splash erosion and wet sieving tests, respectively while the cohesive forces between particles mainly govern soil strength in the fall-cone penetrometer test. The studied soils were clustered based on intrinsic soil properties (i.e., texture, CaCO3 and organic carbon) by using K-means method in MATLAB software, in order to evaluate the capability of different methods in different soil groups. The least significant difference (LSD) test was used in a completely randomized design for mean’ comparisons between the clusters. The mean comparison results showed that the three methods similarly predicted the variation of aggregate stability in different soil clusters. The results of clustering showed that the soil cluster with high organic matter, silt and clay contents and low sand content was more stable than other clusters.
Conclusion Three methods similarly predicted the variation of aggregate stability in different soil groups; therefore, the methods might be used alternatively for aggregate stability determination. Fall-cone penetrometer can be introduced as an in situ method for evaluation of aggregate stability against splash erosion.


Main Subjects

  1. Al-Durrah, M., Bradford, J. 1981. New methods of studying soil detachment due to waterdrop impact. Soil Science Society of America Journal, 45: 949–953.
  2. Angers, D.A., and Carter, M.R. 1996. Aggregation and organic matter storing in cool, humid agricultural soils. In: Carter, M.R., and Stewart, B.A. (Eds.). Structure and Organic Matter Storage in Agricultural Soils. Advanced in Soil Science. Lewis Publishers, CRC Press, Inc., Boca Raton, FL. pp: 193–211.
  3. Barthes, B., and Roose, E. 2002. Aggregate stability as an indicator of soil susceptibility to runoff and erosion; validation at several levels. Catena, 47: 133–149.
  4. Bhattacharyya, R., Fullen, M.A., Davies, K., and Booth, C.A. 2010. Use of palm-mat geotextiles for rainsplash erosion control. Geomorphology, 119: 52–61.
  5. Boix-Fayos, C., Calvo-Cases, A., Imeson, A.C., and Soriano-Soto, M.D. 2001. Influence of soil properties on the aggregation of some Mediterranean soils and the use of aggregate size and stability as land degradation indicators. Catena, 44: 47–67.
  6. Caravaca, F., Lax, A., and Albaladejo, J. 2001.Soil aggregate stability and organic matter in clay and fine silt fractions in urban refuse-amended semiarid soils. Soil Science Society of America Journal, 65: 1235–1238.
  7. Cerda, A. 2000. Aggregate stability against water forces under different climates on agriculture land and scrubland in southern Bolivia. Soil and Tillage Research, 57: 159–166.
  8. Chenu, C., Le Bissonnais, Y., and Arrouays, D. 2000. Organic matter influence on clay wettability and soil aggregate stability. Soil Science Society of America Journal, 64: 1479–1486.
  9. Dexter, A.R., Richard, G., Arrouays, D., Czyż, E.A., Jolivet, C., and Duval, O. 2008. Complexed organic matter controls soil physical properties. Geoderma 144, 620–627.
  10. Elbanna, E.B., and Witney, B.D. 1987. Cone penetration resistance equation as a function of the clay ratio, soil moisture content and specific weight. Journal of Terramechanics 24:41–56.
  11. Emerson, W.W. 1967. A classification of soil aggregates based on their coherence in water. Australian Journal of Soil Research, 5: 47–57.
  12. Havaee, S., Mosaddeghi, M.R., and Ayoubi, S. 2015. In situ surface shear strength as affected by soil characteristics and land use in calcareous soils of central Iran. Geoderma, 237–238: 137–148
  13. Gee, G.W., and Bauder, J.W. 1986. Particle size analysis.  In: Klute, A. (Ed.), Method of Soil Analysis, Part 1. Physical and Mineralogical Methods, Agronomy Handbook No 9. ASA and SSSA, Madison, WI. pp. 383–411.
  14. Jalalian, A. 2011. Soil erorosion and conciquence in the country. 12th Iranian soil congress.3–5 September. Tabriz. Iran. (In persian).
  15. Jaleh, A, 2006. Application of SWAT 2000 model for esimating runoff and ssediment in Vanak wateshed, a sub-basin of northen Karun. Msc thesis, Isfahan university of technology (in persian with english abstract).
  16. Khazaee, A., Mosaddeghi, M.R., Mahboubi, A.A. 2008. Structural stability assessment using wet sieving method and its relations with some intrinsic properties in 21 soil series from Hamedan province. (in persian with english abstract).
  17. Kemper, W., and Rosenau, R. 1986. Aggregate stability and size distribution, In: Klute, A. (Ed.), Methods of Soil Analysis. Part 1. Physical and mineralogical Methods. 2nd ed. ASA, Madison, WI, pp. 425–442.
  18. Khalili Moghadam, B., Jabarifar, M., Bagheri, M., and Shahbazi, E. 2015. Effects of land use change on soil splash erosion in the semi-arid region of Iran. Geoderma, 241–242: 210–220.
  19. Le Bissonnais, Y., Blavet, D., De Noni, G., Laurent, J.Y., Asseline, J., and Chenu, C. 2006. Erodibility of Mediterranean vineyard soils: relevant aggregate stability methods and significant soil variables. European Journal of Soil Science, 58: 188–195.
  20. Le Bissonnais, Y., 1996. Aggregate stability and assessment of soil crustability and erodibility: I. Theory and methodology. European Journal of Soil Science, 47: 425–437.
  21. Nelson, D.W., and Sommers, L.P. 1986. Total carbon, organic carbon and organic matter. In: Buxton, D.R., (Ed.), Method of Soil Analysis, Part 2. Chemical Methods, Agronomy Handbook No 9. ASA and SSSA, Madison, WI. pp. 539–579.
  22. Nelson, R.E. 1982. Carbonate and gypsum. In: Buxton, D.R., (Ed.), Method of Soil Analysis, Part 2. Chemical Methods, Agronomy Handbook No 9. ASA and SSSA, Madison, WI. pp. 181–197.
  23. Sarah, P. 2006. Soil organic matter and land degradation in semi-arid area, Israel. Catena, 67: 50–55.
  24. Saygin, D.S, Cornelis, W., Gabriels, D., and Erpul, G. 2012. Comparison of different aggregate stability approaches for loamy sand soils. Applied Soil Ecology, 54: 1–6.
  25. Saygin, S.D., Erpul, G., and Basaran, M. 2017. Comparison of aggregate stability measurement methods for clay-rich soils in Asartep catchment of Turkey. Land Degradation and Development, 28: 199–206.
  26. Sharma, P.P., Gupta, S.C., and Foster, G.R. 1993. Predicting soil detachment by raindrops. Soil Science Society of America Journal, 57: 674–680.
  27. Shirazi, M.A., and Boersma, L. 1984. A unifying quantitative analysis of soil texture. Soil Science Society of America Journal, 48: 142–147.
  28. Singer, M.J., and Le Bissonnais, Y.L. 1998. Importance of surface sealing in the erosion of some soils from a Mediterranean climate. Geomorphology, 24: 79–85.
  29. Six, J., Elliot, E.T., and Paustian, K. 2000. Soil structure and soil organic matter: II. A normalized stability index and the effect of mineralogy. Soil Science Society of America Journal, 64: 1042–1049.
  30. Towner., G.D. 1973. An examination of the fall-cone method for the determination of some strength properties of remolded agricultural soil. European Journal of Soil Science, 24: 470–479.