Application of Fractional Differential Calculation in Pretreatment of Saline Soil Hyperspectral Reflectance Data

Table 2

Classification criteria of the soil salinization type and soil sample classification statistics.

C(Cl^−)/2C(SO4^2−)	Salinization type	Zone A		Zone B
		Samples	Proportion (%)	Samples	Proportion (%)
<0.20	SO4^2− salt type	22	88.000%	14	46.667%
0.20–1.00	Cl^−-SO4 salt type	3	12.000%	12	40.000%
1.00–2.00	SO4-Cl^− salt type	0	0	3	10.000%
>2.00	Cl^− salt type	0	0	1	3.333%

Note: C(Cl⁻) and C(SO₄²⁻), respectively, represent the millimole amount of Cl⁻ and SO₄²⁻ contained in 100 g soil.