Stoner Shane W, Hoyt Alison M, Trumbore Susan, Sierra Carlos A, Schrumpf Marion, Doetterl Sebastian, Baisden W Troy, Schipper Louis A
Max Planck Institute for Biogeochemistry, Jena, Germany.
Department of Environmental Systems Science, ETH Zürich, Zurich, Switzerland.
Biogeochemistry. 2021;156(1):145-160. doi: 10.1007/s10533-021-00838-z. Epub 2021 Aug 27.
Managed grasslands have the potential to store carbon (C) and partially mitigate climate change. However, it remains difficult to predict potential C storage under a given soil or management practice. To study C storage dynamics due to long-term (1952-2009) phosphorus (P) fertilizer and irrigation treatments in New Zealand grasslands, we measured radiocarbon (C) in archived soil along with observed changes in C stocks to constrain a compartmental soil model. Productivity increases from P application and irrigation in these trials resulted in very similar C accumulation rates between 1959 and 2009. The ∆C changes over the same time period were similar in plots that were both irrigated and fertilized, and only differed in a non-irrigated fertilized plot. Model results indicated that decomposition rates of fast cycling C (0.1 to 0.2 year) increased to nearly offset increases in inputs. With increasing P fertilization, decomposition rates also increased in the slow pool (0.005 to 0.008 year). Our findings show sustained, significant (i.e. greater than 4 per mille) increases in C stocks regardless of treatment or inputs. As the majority of fresh inputs remain in the soil for less than 10 years, these long term increases reflect dynamics of the slow pool. Additionally, frequent irrigation was associated with reduced stocks and increased decomposition of fresh plant material. Rates of C gain and decay highlight trade-offs between productivity, nutrient availability, and soil C sequestration as a climate change mitigation strategy.
The online version contains supplementary material available at 10.1007/s10533-021-00838-z.
管理的草原具有储存碳（C）和部分缓解气候变化的潜力。然而，在给定的土壤或管理实践下，预测潜在的碳储存仍然很困难。为了研究新西兰草原长期（1952 - 2009年）磷肥和灌溉处理导致的碳储存动态，我们测量了存档土壤中的放射性碳（C）以及观察到的碳储量变化，以约束一个土壤分区模型。在这些试验中，磷肥施用和灌溉导致的生产力增加在1959年至2009年间产生了非常相似的碳积累速率。在灌溉和施肥的地块中，同一时期的∆C变化相似，仅在未灌溉施肥的地块中有所不同。模型结果表明，快速循环碳（0.1至0.2年）的分解速率增加，几乎抵消了输入量的增加。随着磷肥施用量的增加，慢库（0.005至0.008年）中的分解速率也增加。我们的研究结果表明，无论处理或输入如何，碳储量都持续显著（即大于4‰）增加。由于大部分新鲜输入在土壤中停留不到10年，这些长期增加反映了慢库的动态。此外，频繁灌溉与碳储量减少和新鲜植物材料分解增加有关。碳的增加和衰减速率突出了生产力、养分有效性和作为气候变化缓解策略的土壤碳固存之间的权衡。
在线版本包含可在10.1007/s10533-021-00838-z获取的补充材料。
