Introduction: Roots are important organs that supply water, nutrients, hormones,and mechanical support (anchorage) to crop plants and, consequently, affecteconomic yields. In addition, roots improve soil organic matter (OM) bycontributing to soil pools of organic carbon (C), nitrogen (N), and microbialbiomass. Root-derived soil C is retained and forms more stable soil aggregatesthan shoot-derived soil C. Although roots normally contribute only 10%–20% oftotal plant weight, a well-developed root system is essential for healthy plantgrowth and development (Fageria, 2013).
Rootsystems of crops play a vital role in improving soil health. Below-groundbiomass often referred to as ‘root biomass’ is considered as one of the mostrelevant parameters of plant system on account of its significant role inmaintaining soil organic carbon in response to environmental changes (Hirte etal., 2017). Below-ground biomass is an important carbon pool for manyvegetation types and land-use systems and accounts for about 20% (Santantonioet al. 1977) to 26% (Cairns et al.
1997) of the total biomass. Below-groundbiomass accumulation is linked to the dynamics of above-ground biomass. Thegreatest proportion of root biomass occurs in the top 30 cm of the soil surface(Bohm 1979; Jackson et al. 1996). Below-groundbiomass is defined as the entire biomass of all live roots, although fine rootsless than 2 mm in diameter are often excluded because these cannot easily bedistinguished empirically from soil organic matter (Anon., 2008).
Live and deadroots are generally not distinguished and hence root biomass is reported astotal of live and dead roots; and also the presence of extraneous organicmatter in soil including dead roots from previous crops, weed roots,incorporated above ground plant residues and organic soil amendments, orremnants of soil fauna (Hirte et al., 2017). Thebiomass accumulated below the ground acts like a store house of carbon. Generallythe amount of carbon stored in soil represents the balance between above groundshoot dry matter and below ground root biomass production, root exudates andtheir microbial decomposition. In this review an attempt has been made toprovide an overview on the contribution of root biomass in maintaining rhizospheresoil carbon status and their association with microbial activity.