Combined effects of rhizodeposit C and crop residues on SOM priming, residue mineralization and N supply in soil
Combined effects of rhizodeposit C and crop residues on SOM priming, residue mineralization and N supply in soil
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DOI：
10.1016/j.soilbio.2017.05.026
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发表时间：
2017-10
影响因子：
9.7
通讯作者：
Lumbani Mwafulirwa;E. Baggs;J. Russell;N. Morley;A. Sim;E. Paterson
中科院分区：
文献类型：
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作者：
Lumbani Mwafulirwa;E. Baggs;J. Russell;N. Morley;A. Sim;E. Paterson
根际沉积碳 (C) 向土壤的通量刺激微生物活动，影响土壤有机质 (SOM) 的分解，进而影响土壤中的养分通量。在农业土壤中，前茬作物的残留物也对有机质和养分循环产生重大影响，微生物的周转可能会受到根际沉积的间接影响。然而，根际沉积碳和土壤中死亡植物材料输入的碳对天然有机质分解的综合影响尚不清楚。在本研究中，我们评估了（i）大麦根际沉积和黑麦草根残留物输入（作为前茬作物残留物输入的模型）对SOM矿化的单独和综合影响，（ii）大麦内影响残留物矿化的种内变异，以及（iii）刺激土壤中植物残留物高矿化率的基因型是否也通过增加从这些残留物中吸收养分而直接受益。我们连续将 13 C 消耗的 CO2 应用于选定的大麦重组染色体替换系 (RCSL)，以追踪大麦根部来源的 C 在表层土壤 CO2 流出、土壤微生物生物量和土壤颗粒尺寸部分中的流动。此外，将富含 13 C 和 15 N 的黑麦草根残留物混合到土壤中，以追踪残留物来源的 C 的矿化和植物对残留物来源的氮 (N) 的吸收。我们的结果显示 (i) 影响土壤总 CO2 流出量及其成分来源的基因型特异性变化：SOM 衍生的 C、大麦根衍生的 C 和/或黑麦草残留衍生的 C，(ii) 残留物对总 C 和 SOM 衍生的 C 呼吸为 CO2 的影响，(iii) 基因型-残留物对 SOM 引发的 C 的综合影响，与单独种植或残留物添加引起的引发的 C 的总和非常相似（最后一次采样除外）日期），以及（iv）植物对基因型之间残留物释放的氮的吸收与基因型对残留物矿化的影响有关。这些结果表明，植物根际沉积和残留物输入的影响对 SOM 启动具有累加效应。此外，这些结果首次证明了基因型差异对土壤中近期植物源性有机材料矿化的影响，并揭示了这一过程直接有助于植物营养。
Fluxes of rhizodeposit carbon (C) to soil stimulate microbial activity affecting soil organic matter (SOM) decomposition and, in turn, nutrient fluxes in soil. In agricultural soils, residues from previous crops also have major impacts on SOM and nutrient cycling, and their turnover by microbes is likely to be indirectly impacted by rhizodeposition. However, the combined effects of rhizodeposit C and inputs of C from dead plant materials in soil on native SOM decomposition are unclear. In this study, we assessed (i) the individual and combined effects of barley rhizodeposition and ryegrass root residue inputs (as a model for residue input from previous crop) on SOM mineralization, (ii) the intraspecies variation within barley in impacting residue mineralization, and (iii) whether genotypes that stimulate high mineralization rates of plant residues in soil also directly benefit through increased nutrient uptake from these residues. We continuously applied13C depleted CO2to selected barley recombinant chromosome substitution lines (RCSLs) to trace the flow of barley root-derived C in surface soil CO2efflux, soil microbial biomass and soil particle-size fractions. In addition,13C and15N enriched ryegrass root residues were mixed into soil to trace the mineralization of residue-derived C and the residue-derived nitrogen (N) uptake by plants. Our results show (i) genotype-specific variation in impacting total soil CO2efflux and its component sources: SOM-derived C, barley root-derived C and/or ryegrass residue-derived C, (ii) residue effects on total C and SOM-derived C respired as CO2, (iii) genotype-residue combined effects on SOM primed C, that were very similar to the sum of primed C caused by planting or residue addition alone (except for the last sampling date), and (iv) that plant uptake of residue released N between genotypes was linked to genotype impacts on residue mineralization. These results suggest that impacts of plant rhizodeposition and residue inputs had additive effects on SOM priming. Furthermore, these results demonstrate, for the first time, genotype differences in impacting the mineralization of recent plant-derived organic materials in soil, and reveal that this process directly contributes to plant nutrition.