Department of Sustainable Agriculture Sciences, Rothamsted Research, West Common, Harpenden, AL5 2JQ, Hertfordshire, UK.
School of Water, Energy & Environment, Cranfield University, Cranfield, MK43 0AL, Bedfordshire, UK.
Sci Rep. 2022 Mar 25;12(1):5162. doi: 10.1038/s41598-022-09101-3.
Realistic targets for soil organic carbon (SOC) concentrations are needed, accounting for differences between soils and land uses. We assess the use of SOC/clay ratio for this purpose by comparing changes over time in (a) the National Soil Inventory of England and Wales, first sampled in 1978-1983 and resampled in 1994-2003, and (b) two long-term experiments under ley-arable rotations on contrasting soils in the East of England. The results showed that normalising for clay concentration provides a more meaningful separation between land uses than changes in SOC alone. Almost half of arable soils in the NSI had degraded SOC/clay ratios (< 1/13), compared with just 5% of permanent grass and woodland soils. Soils with initially large SOC/clay ratios (≥ 1/8) were prone to greater losses of SOC between the two NSI samplings than those with smaller ratios. The results suggest realistic long-term targets for SOC/clay in arable, ley grass, permanent grass and woodland soils are 1/13, 1/10, and > 1/8, respectively. Given the wide range of soils and land uses across England and Wales in the datasets used to test these targets, they should apply across similar temperate regions globally, and at national to sub-regional scales.
需要设定现实的土壤有机碳（SOC）浓度目标，以考虑土壤和土地利用之间的差异。为此，我们通过比较英格兰和威尔士国家土壤调查（于 1978-1983 年首次采样，于 1994-2003 年再次采样）以及在英格兰东部两种具有差异的土壤上进行的长期休闲-轮作试验（a）和（b）中随时间的变化，评估 SOC/粘粒比在这方面的应用。结果表明，与 SOC 单独变化相比，粘粒浓度归一化提供了一种更有意义的土地利用区分方法。与永久性草地和林地土壤相比，近一半的 NSI 耕地土壤的 SOC/粘粒比（<1/13）下降。在最初 SOC/粘粒比（≥1/8）较大的土壤中，两次 NSI 采样之间 SOC 的损失比那些比值较小的土壤更容易发生。结果表明，耕地、休闲草地、永久性草地和林地土壤中 SOC/粘粒的现实长期目标分别为 1/13、1/10 和>1/8。鉴于用于测试这些目标的数据集涵盖了英格兰和威尔士广泛的土壤和土地利用类型，这些目标应该适用于全球类似的温带地区，以及国家到次区域的尺度。
