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).