and application of other necessary fertilizers, are important in order to use these soils
for agricultural production.
Figure 5.28 shows an example of natrojarosite. The sample field is presently used
for sugarcane production (Fig. 5.28a). In the soil profile, the yellow patches at a
depth of approximately 60 cm from the soil surface (Fig. 5.28b) are natrojarosite.
The SEM image (Fig. 5.28c) shows pseudocubic crystal forms, and the EDX
spectrum (Fig. 5.28d) obtained from the dashed square area (Fig. 5.28c) shows
significant peaks for Na, S, and Fe. The powder XRD pattern (Fig. 5.28e) is similar
to the reference pattern of natrojarosite (Fig. 5.28f).
Further readings for submerged soils and wetland soils are Kirk (2004), and
Vepraskas and Craft (2016).
Fig. 5.27 Morphological properties of framboidal pyrite. (a) optical micrograph of framboidal
pyrite particles, (b) magnified SEM image of a framboidal pyrite particle, (c) octahedral-type
particles in framboidal pyrite, (d) polyhedral or rounded particles in framboidal pyrite
128
5 Inorganic Soil Constituents Sensitive to Varying Redox Conditions