4.3 Effect of grass-legume mixture on soil CO2flux
The decomposition of grass-legume mulch over 5-years of revegetation,
influence microbial respiration and increased CO2 flux
of the reclaimed waste dump by 19%. Soil CO2 flux
attributed by natural forest was 1.5 times greater than the 5-years old
reclaimed waste dump (Figure 8). Variation in the rate of soil
CO2 fluxes can be due to the difference in soil
temperature, litter/biomass input, and plant root growth (Frouz, 2017).
Higher N concentration of the legume shoot and root residues showed an
efficacious effect on soil N pool whereas higher root C in grass residue
built soil C pool and increases CO2 efflux and their
addition as mulch available for microbes increases the soil microbial
respiration throughout the stages of decomposition. An increase in
labile C pool would increase soil respiration as the grass biomass
residues reduce N leaching i. e. positive priming effect (Frouz,
Novotna, Cermakova, & Pivokonsky, 2020; Wu et al., 2020). Root
biomass-derived C compared to shoot biomass C have been reported to
contribute greater and relatively stable soil C pools (Ghafoor, Poeplau,
& Katterer, 2017). Apparently, these differences gradually declined
during microbial decomposition because soil C:N ratio decreased after
1-5 years of revegetation (Table 3). Liu et al. (2020) reported the
benefits of legume biomass (Caragana korshinskii ) on the Loess
Plateau of China showed greater potential to sequester soil C.
Similarly, 7-years of perennial legume M. sativa, Lespedeza
davurica, and Astragalus adsurgens growth increased the soil C
sequestration of arable land by 79, 68 and 74% (Guan et al., 2016). The
rate of CO2 flux, unlike other soil parameters, respond
more quickly under varying soil temperature and the quality of organic
matter to assess soil fertility (Ahirwal, Maiti, & Singh, 2017b;
Munoz-Rojas, Erickson, Dixon, & Merritt, 2016) indicating whether the
soil conditions are favorable for decomposition process in long term
revegetation.