Xu YH Chen ZM Ding WX Fan JL. Responses of manure decomposition to nitrogen addition: Role of chemical composition. Science of The Total Environment 2017 doi: 10.1016-j.scitotenv.2017.02.033
Abstract
Understanding the interactions among organic manure chemical composition decomposition and nitrogen (N) fertilization is critical for sustainable agriculture management. Six organic manures were incubated in a cultivated black soil with or without N addition for one year and carbon dioxide (CO2) emissions from these organic manures were monitored. Chemical compositions of the organic manures were determined by elemental analysis proximate chemical analysis and carbon (C)-13 nuclear magnetic resonance spectroscopy and evaluated after cupric-oxide oxidation for lignin biomarkers. During the experimental period 19–44% of manure C was decomposed without N addition which decreased to 17–35% with N addition except for the composted furfural residue with rice dregs. However during different decomposition stages N effect changed from stimulation to inhibition or behaved as increasing inhibition. During stage 1 (days 0–100) when N stimulation effect reached a maximum CO2 emissions from manure had positive relationships with labile C fraction indicators including total sugars soluble polyphenols and lignin cinnamyl-vanillyl ratio regardless of N addition. N effect on manure decomposition was related to the C-N ratio and labile organic C content. During stage 2 (days 101–267) N effect shifted to inhibition with CO2 emissions from manure negatively related to lignin vanillyl-units content. The magnitude of N inhibition increased linearly with the aromaticity of dissolved organic C and was strengthened by nitrate in manure. Finally N inhibition effect reached a maximum during stage 3 (days 268–365) increasing with higher aromatic C in manure. Critical factors for manure decomposition shifted from total sugars soluble polyphenols and lignin cinnamyl-units to recalcitrant lignin vanillyl-units and aromatic C fraction which mediated the type and magnitude of N effect on decomposition. Our results suggested that the potential for enhancing soil C sequestration with organic manures would magnify under combined application with N fertilizer in the long term.
