2.1. Spaceborne
Spaceborne remotely sensed imagery possess the power to generate spatial
maps of higher soil horizon due to association of soil’s definite
chemical bonds as well as electromagnetic radiations. With inauguration
of first satellite in 1980s, optical satellite multispectral imagery
finds extensive applications in SOC estimation (quantitative) (Frazier
and Cheng 1989). Additionally, owing to availability of Hyperion
spaceborne system, usage of hyperspectral data also increased (Castaldi,
Casa et al. 2014). However, their application for soil study was
restricted owing to essential atmospheric, geometric, radiometric data
amendment, obstacles in uncovering naked regions in one image (Demattê,
Fongaro et al. 2018), as well as hurdles associated with vegetation
cover (Barnes, Sudduth et al. 2003). Owing to these reasons studies on
SOC estimation via satellite sensors are not many (Croft, Kuhn et al.
2012). Nowadays there is a remarkable change in SOC estimation as well
as mapping founded on spaceborne data. One of the major achievements in
this regard is relevant USGS policy variation (for dispersion of Landsat
data freely) (Woodcock, Allen et al. 2008). Additionally, upcoming
hyperspectral sensors i.e., Environmental Mapping and Analysis Program
(EnMAP) shortly give unprecedental statistics for SOC estimation across
VNIR-SWIR spectral span (Stuffler, Kaufmann et al. 2007).