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The determination of carbon-based biomass blending ratio was a prerequisite for the large-scale development of the coupled combustion technology of biomass and coal. In this study, the experimental system of the radiocarbon method to detect the carbon-based biomass blending ratio by analyzing the flue gases produced during coupled combustion was built, and the calculation model of the carbon-based biomass blending ratio was proposed, and the accuracy and precision of the radiocarbon method were evaluated. The results showed that there was a good linear relationship between the 14C concentration of CO2 samples and biogenic fractions in flue gas. The application of the new calculation model improved the accuracy of the 14C determination method, and the relative error increased as the carbon-based biomass blending ratio decreased in the 14C method: the minimum relative error of the carbon-based biomass blending ratio with carbon-based assay was 15.16%,12.21%, 9.61%, 7.96% and 3.13% when considering coal and air simultaneously in AMS analysis. This further validated the 14C determination method as an accurate method for identifying the carbon-based biomass blending ratio in biomass and coal coupled combustion.

Urease inhibitor (UI) and nitrification inhibitor (NI) can reduce N losses from agricultural soils but effects of inhibitors on N cycle are unclear. A field experiment was conducted with maize to test effects of UI (N-(n-Butyl) thiophosphoric, NBPT) and NI (3,4-dimethylepyrazolephosphate, DMPP) on N uptake and N-cycling soil microbes. Five treatments were imposed: no N fertilizer input (CK), conventional fertilization (CF) and 80% of urea input with NBPT (80%U+UI), with DMPP (80%U+NI) and with half NBPT and half DMPP (80%U+1/2(UI+NI)). There were no significant differences in biomass between 80%U+UI, 80%U+NI and CF but harvest index was increased under 80%U+UI and 80%U+NI. Compared to CF, N use efficiency of grain under 80%U+UI was increased by 7.1%, whereas grain yield and N uptake under 80%U+1/2(UI+NI) were decreased by 8.2% and 9.4%, respectively. The peak soil [Formula: see text] content was at about 15 days after fertilization (DAF) under CF but 30 DAF under the inhibitor treatments. In soils of 80%U+UI, the activities of urease and nitrate reductase were decreased between 15-45 DAF and between 5-30 DAF. The abundance of N-cycling soil microbes was affected: 80%U+UI and 80%U+NI reduced the copies of the amoA AOA and nir genes at about 15 days and reduced the copies of the amoA AOB gene at about 30 days. Correlation analysis indicated that there were significant positive relationships between amoA AOB gene and [Formula: see text], as well as between nirK gene and [Formula: see text]. Overall, urea applied with NBPT has greater potential for improving maize N use efficiency and inhibiting nitrification under reduced fertilizer-N applications.