Dataset from Soil N and dissolved organic matter chemodiversity: bacterial utilization of soil C and effects on N mineralization after six years of organic and inorganic fertilization
Description
We hypothesized that: ⅰ) continuous application of chemical fertilizer and decomposed cow manure alone or in combination can alter soil DOM compositions and mediate strategies for bacterial utilization of soil carbon and, ⅱ) DOM composition and soil nitrogen vary in their relative contributions to nitrogen mineralization in this study. The data included soil organic carbon and total N in paddy soil from 2015 to 2020, alkaline-nitrogen, NO3-N and NH4-N in paddy soil in 2020, the molecular composition of the DOM in soil analyzed by FT-ICR-MS in 2020, bacteria composition in soil 2018 and 2020 under the treatments of organic and inorganic fertilization. We highlighted continuous decomposed cow manure application increased soil nitrogen and recalcitrant components of DOM that mediated the strategies for bacterial carbon utilization and affected the nitrogen mineralizaiton. Total-nitrogen (TN), alkaline-nitrogen (AN) and bacterial diversity played an important effect on nitrogen mineralization, as well as lipids presented a positively total effect on nitrogen mineralization stronger than protein/amino sugars. However, tannins, lignins, condensed aromatics, carbohydrates, and unsaturated hydrocarbons showed a negatively total effect on nitrogen mineralization.
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TN were measured with an elemental analyzer (multi N/C 2100/2100S, Analytik Jena). The mineral nitrogen (NH4−N + NO3−N) was determined in subsamples, after extraction with 2 M KCl, using an automatic nitrogen analyzer (FUTURA, Alliance) (Keeney and Nelson, 1982). Alkaline-nitrogen was measured as described by Xiong et al. (2008). Dissolved organic carbon (DOC) was determined as described by Jones & Willett (2006). The DOM was extracted with Milli-Q water and quantified as described by Xiao-Ming et al. (2018).Total genome DNA was extracted from each 0.5 g soil sample using an E.Z.N.A.® Soil DNA Kit (Omega Bio-tek), following the manufacturer’s protocols. The V4 regions of the bacterial 16S ribosomal RNA genes were amplified by PCR utilizing the primers 515F (GTGCCAGCMGCCGCGGTAA) and 806R (GGACTACNNGGGTATCTAAT). Finally, 16S rRNA gene sequencing was performed on an Illumina NovaSeq platform and 250 bp paired-end reads were generated. Each molecule intensity from the DOM samples was normalized to the sum of all intensities of given spectrum by FT-ICR-MS. Thus, the relative intensities were used for statistical analyses in this study (Osterholz et al., 2016). Biomolecular compound groups of DOM was categories according to the stoichiometry of their molecular formulas by the modified aromaticity index (AI) and elemental ratios (H/C and O/C), including lipids (H/C=1.5-2.0, O/C=0-0.3), proteins/amino sugars (H/C=1.5-2.2, O/C=0.3-0.67, N/C≥0.05), carbohydrates (H/C=1.2-2.2, O/C=0.67-1.2), lignins (H/C=0.7-1.5, O/C=0.1-0.67, AI﹤0.67), unsaturated hydrocarbons (H/C=0.7-1.5; O/C=0-0.1), tannins (O/C=0.67-1.2, H/C=0.5-1.5, AI﹤0.67) and condensed aromatics (H/C=0.2-0.7, O/C=0-0.67, AI≥0.67) (Feng et al., 2016; Xiao-Ming et al., 2018; Huang et al., 2020; Yang et al., 2020). Principal coordinate analysis (PCoA) plots were used to assess the variation in the composition of microbial communities between treatments and to visualise potential clustering of treatments. Clustering correlation heatmap with signs and correlation network were performed using the OmicStudio tools at https://www.omicstudio.cn. to reveal the correlation between DOM chemodiversity and bacterial community composition. Where the p-values < 0.05 and the correlation threshold were ≥0.6 or ≤-0.6 to show the key linkages. Strucural equation modeling (SEM) was conducted using AMOS 21.0 to determine the effects of soil nitrogen, carbon, microbial properties and DOM composition on the nitrogen mineralization.