Exogenous nutrients and carbon resource change the responses of soil organic matter decomposition and nitrogen immobilization to nitrogen deposition

Abstract

It is unclear whether exogenous nutrients and carbon (C) additions alter substrate immobilization to deposited nitrogen (N) during decomposition. In this study, we used laboratory microcosm experiments and 15N isotope tracer techniques with five different treatments including N addition, N+non-N nutrients addition, N+C addition, N+non-N nutrients+C addition and control, to investigate the coupling effects of non-N nutrients, C addition and N deposition on forest floor decomposition in subtropical China. The results indicated that N deposition inhibited soil organic matter and litter decomposition by 66% and 38%, respectively. Soil immobilized 15N following N addition was lowest among treatments. Litter 15N immobilized following N addition was significantly higher and lower than that of combined treatments during the early and late decomposition stage, respectively. Both soil and litter extractable mineral N were lower in combined treatments than in N addition treatment. Since soil N immobilization and litter N release were respectively enhanced and inhibited with elevated non-N nutrient and C resources, it can be speculated that the N leaching due to N deposition decreases with increasing nutrient and C resources. This study should advance our understanding of how forests responds the elevated N deposition.

Preferential Alternatives to Returning All Crop Residues as Biochar to the Crop Field? A Three-Source 13C and 14C Partitioning Study

“…Specifically, microbes likely preferentially consumed the labile C rather than supporting co-metabolism; thus, the biochar was largely mineralized. Preferential microbial utilization of exogenous C sources is also consistent with a reported biochar-induced negative priming effect on SOM in the initial 10–20 days . During 50–180 day incubation, biochar mediated successively positive priming effects on SOM.…”

“…Preferential microbial utilization of exogenous C sources is also consistent with a reported biochar-induced negative priming effect on SOM in the initial 10−20 days. 31 During 50−180 day incubation, biochar mediated successively positive priming effects on SOM. The decomposition rate was as slow as 0.00043 mg biochar-induced C g −1 soil day −1 , which was clearly lower than the magnitudes of SOM-induced CO 2 emission (0.045 mg C soil day −1 ) and priming effects (0.062 mg C soil day −1 ).…”

Fertilization increases the functional specialization of fine roots in deep soil layers for young Eucalyptus grandis trees

“…Tracer availability for tree roots may have differed depending on depth and element properties. N microbial immobilization increases with soil organic resources (He et al, 2016) and NO 3…”

Organic Matter Decomposition and Nutrient Release from Different Dhaincha (Sesbania spp.) Genotypes

“…The biochemical properties of green biomass play an important role in the decomposition process and nutrient release from an organic source. The C:N ratio of plant biomass dominates the decomposition rate within a single climate zone (He et al, 2016;Thӧnnissen et al, 2000). The water-soluble fractions of green manure get metabolized early followed by cellulose and hemicellulose.…”