Table 2: the parameters of the quadratic equation b1, b2 and b3 calculated by proposed PTFs.

The Parameters of the Quadratic Equation Developed PTFs by Nonlinear Regression
PTFs developed using soil texture
b1 4.96×10-8.exp (8.67×10-3.sand -1.4×10-2.silt +1.03×10-2.clay)
b2 1.551× 10-6 .exp (5.33×10-3.sand+2.33×10-3.silt-2.67×10-3.clay)
b3 3.5 ×10-6 .exp (1.83×10-2.sand+1×10-3.silt-3.3×10-3.clay)
PTFs developed using soil texture and soil bulk density
b1 3.72×10-8.exp (0.0062.sand -0.01.silt +0.0078.clay+0.43.B.D)
b2 1.86 × 10-6 .exp (0.004.sand+0.0017.silt-0.002.clay-0.11.B.D)
b3 4.95 ×10-6 .exp (0.014.sand+0.00075.silt-0.0025.clay-0.24.B.D)
PTFs developed using soil texture, soil bulk density, and organic matter
b1 3.65×10-8.exp (0.0052.sand -0.0084.silt +0.0062.clay+0.35.B.D-0.034.O.M)
b2 1.81 × 10-6 .exp (0.0032.sand+0.0014.silt-0.0016.clay-0.09.B.D+0.01.O.M
b3 4.54 ×10-6 .exp (0.011.sand+0.0006.silt-0.002.clay-0.19.B.D+0.024.O.M)

* B.D: soil bulk density (g/cm3), O.M: organic matter (g/100g soil).