New Zealand Institute for Plant & Food Research Limited, Christchurch, New Zealand.
AgResearch, Lincoln Research Centre, Christchurch, New Zealand.
Glob Chang Biol. 2017 Nov;23(11):4544-4555. doi: 10.1111/gcb.13720. Epub 2017 May 16.
Understanding soil organic carbon (SOC) sequestration is important to develop strategies to increase the SOC stock and, thereby, offset some of the increases in atmospheric carbon dioxide. Although the capacity of soils to store SOC in a stable form is commonly attributed to the fine (clay + fine silt) fraction, the properties of the fine fraction that determine the SOC stabilization capacity are poorly known. The aim of this study was to develop an improved model to estimate the SOC stabilization capacity of Allophanic (Andisols) and non-Allophanic topsoils (0-15 cm) and, as a case study, to apply the model to predict the sequestration potential of pastoral soils across New Zealand. A quantile (90th) regression model, based on the specific surface area and extractable aluminium (pyrophosphate) content of soils, provided the best prediction of the upper limit of fine fraction carbon (FFC) (i.e. the stabilization capacity), but with different coefficients for Allophanic and non-Allophanic soils. The carbon (C) saturation deficit was estimated as the difference between the stabilization capacity of individual soils and their current C concentration. For long-term pastures, the mean saturation deficit of Allophanic soils (20.3 mg C g ) was greater than that of non-Allophanic soils (16.3 mg C g ). The saturation deficit of cropped soils was 1.14-1.89 times that of pasture soils. The sequestration potential of pasture soils ranged from 10 t C ha (Ultic soils) to 42 t C ha (Melanic soils). Although meeting the estimated national soil C sequestration potential (124 Mt C) is unrealistic, improved management practices targeted to those soils with the greatest sequestration potential could contribute significantly to off-setting New Zealand's greenhouse gas emissions. As the first national-scale estimate of SOC sequestration potential that encompasses both Allophanic and non-Allophanic soils, this serves as an informative case study for the international community.
了解土壤有机碳（SOC）固存对于制定增加 SOC 储量的策略很重要，从而抵消一些大气二氧化碳的增加。尽管土壤以稳定形式储存 SOC 的能力通常归因于细颗粒（粘土+细粉砂）部分，但决定 SOC 稳定能力的细颗粒特性知之甚少。本研究的目的是开发一种改进的模型来估计含层状矿物（Andisols）和非含层状矿物（0-15cm）表土的 SOC 稳定能力，并作为案例研究，应用该模型预测新西兰牧场地土壤的固碳潜力。基于土壤的比表面积和可提取的铝（焦磷酸盐）含量的分位数（90%）回归模型提供了对细颗粒碳（FFC）上限（即稳定能力）的最佳预测，但含层状矿物和非含层状矿物的土壤有不同的系数。碳（C）饱和度亏缺估计为单个土壤的稳定能力与其当前 C 浓度之间的差异。对于长期牧场，含层状矿物土壤的平均饱和度亏缺（20.3mg C g）大于非含层状矿物土壤（16.3mg C g）。耕作土壤的饱和度亏缺是牧场土壤的 1.14-1.89 倍。牧场地土壤的固碳潜力范围从 10t C ha（Ultic 土壤）到 42t C ha（Melanic 土壤）。尽管实现估计的全国土壤 C 固存潜力（124Mt C）是不现实的，但针对具有最大固存潜力的土壤实施的改进管理实践可以显著有助于抵消新西兰的温室气体排放。作为第一个涵盖含层状矿物和非含层状矿物土壤的全国范围内的 SOC 固碳潜力的估计，这为国际社会提供了一个有启发性的案例研究。
