Short-Term Mineralization of Belowground Biomass of Perennial Biomass Crops after Reversion to Arable Land

Little is known about the effect of perennial biomass crops (PBCs) removal on soil C dynamics. The belowground (BGB) that composed by plant organs (PBO) such as rhizomes in herbaceous PBCs and stumps woody should be considered, together with fine roots (FR), a huge input exogenous organic matter (EOM) incorporated into at reversion. In this study, we mimic incorporation BGB through soil-residues incubation under controlled conditions to investigate effects adding FR PBO (at real field rates) N mineralization dynamics, understand decomposition controlling factors. A modified RothC model version, encompassing better description decomposable (DEOM) resistant (REOM) pools, was fitted curves respiration measured CO2 evolution incubated quantify partitioning factors rates components. After 1 month, showed higher (498 µg CO2-C gsoil−1) than (196 gsoil−1), black locust having highest amount respired (38% added C). emission peak occurred within 3 days from beginning experiment for after day FR. Generally, according version model, had proportion REOM FR, except locust. constant optimized were (kDEOM: 20.9 y−1, kREOM: 12.1 y−1) 0.4 0.1 y−1), indicating are less PBO. C/N ratio not main factor when residue limiting factor, while availability easily substrates (DEOM/REOM ratio) cell-wall composition strong predictor these EOM types. explicit inclusion crop-specific DEOM/REOM ratios or similar will help improve predictions long-term sequestration trajectories (half-life > 30 years) associated cultivation, especially dismission cropping systems addressed.