University of Tabriz Water and Soil Science 2008-5133 26 3 2016 11 21 The Effect of Different Na/K Ratios in Soil Solution on Aggregate Tensile Strength and Friability The Effect of Different Na/K Ratios in Soil Solution on Aggregate Tensile Strength and Friability 161 174 5542 FA H Emami A Fotovat R Khorassani K Esmaeeli Journal Article 2015 05 19 This research was carried out to study the effect of different ratio of Na/K in soil solution on dispersible clay, aggregate tensile strength and soil friability using the cation ratio of soil structural stability (CROSS) index. In order to apply different potassium concentrations, 6 treatments with the same EC (3 dS m^-1) including 0 to 27.2 meqL^-1 K⁺ and another six treatments with EC=6 dS m^-1 including 0 to 54.4 meqL^-1 K⁺ were prepared and added to soil. Soil friability was calculated and compared through two methods i.e. the coefficient of variation (F₁) and ranking order (F₂). The results showed that increasing the K⁺ concentration in treatments relative to Na⁺ could increase the water dispersible clay. Also, the results of aggregates tensile strength test showed that in treatments with EC=3 dS m^-1by increasing the K⁺value, the soil strength decreased but with increasing the SAR value, soil strength increased. Maximum amount of tensile strength (142 kPa) was observed in treatment 1 with CROSS = 25.7 and SAR=22.9 and the minimum amount (87 kPa) was in treatment 5 with CROSS=14.8 and SAR=0.99. This trend was not observed in treatments with EC=6 dS m^-1and the aggregate tensile strengths were almost similar in all treatments. The results demonstrated that soil friability (F₁ & F₂) increased with increasing the dispersible clay at EC=3. Comparison of the results of tensile strength and friability revealed that F₁ was inappropriate parameter for expression of soil friability while F₂ showed the good agreement with the strength and friability amounts (in treatments with EC=3). In treatments with EC=6, the effect of dispersible clay on tensile strength and friability was not observed, probably due to the higher concentration of the soil solution.  This research was carried out to study the effect of different ratio of Na/K in soil solution on dispersible clay, aggregate tensile strength and soil friability using the cation ratio of soil structural stability (CROSS) index. In order to apply different potassium concentrations, 6 treatments with the same EC (3 dS m^-1) including 0 to 27.2 meqL^-1 K⁺ and another six treatments with EC=6 dS m^-1 including 0 to 54.4 meqL^-1 K⁺ were prepared and added to soil. Soil friability was calculated and compared through two methods i.e. the coefficient of variation (F₁) and ranking order (F₂). The results showed that increasing the K⁺ concentration in treatments relative to Na⁺ could increase the water dispersible clay. Also, the results of aggregates tensile strength test showed that in treatments with EC=3 dS m^-1by increasing the K⁺value, the soil strength decreased but with increasing the SAR value, soil strength increased. Maximum amount of tensile strength (142 kPa) was observed in treatment 1 with CROSS = 25.7 and SAR=22.9 and the minimum amount (87 kPa) was in treatment 5 with CROSS=14.8 and SAR=0.99. This trend was not observed in treatments with EC=6 dS m^-1and the aggregate tensile strengths were almost similar in all treatments. The results demonstrated that soil friability (F₁ & F₂) increased with increasing the dispersible clay at EC=3. Comparison of the results of tensile strength and friability revealed that F₁ was inappropriate parameter for expression of soil friability while F₂ showed the good agreement with the strength and friability amounts (in treatments with EC=3). In treatments with EC=6, the effect of dispersible clay on tensile strength and friability was not observed, probably due to the higher concentration of the soil solution.  https://water-soil.tabrizu.ac.ir/article_5542_d7b18b4833930ebcf57d1bb832ff8b8c.pdf