Hebei Provincial Key Laboratory of Soil Ecology, Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetic and Developmental Biology, The Chinese Academy of Sciences, 286 Huaizhong Road, Shijiazhuang 050021, Hebei, China.
Department of Agriculture and Life Sciences, Lincoln University, Lincoln, New Zealand.
Sci Adv. 2023 Feb 10;9(6):eadd0041. doi: 10.1126/sciadv.add0041. Epub 2023 Feb 8.
Even a small net increase in soil organic carbon (SOC) mineralization will cause a substantial increase in the atmospheric CO concentration. It is widely recognized that the SOC mineralization within deep critical zones (2 to 12 m depth) is slower and much less influenced by anthropogenic disturbance when compared to that of surface soil. Here, we showed that 20 years of nitrogen (N) fertilization enriched a deep critical zone with nitrate, almost doubling the SOC mineralization rate. This result was supported by corresponding increases in the expressions of functional genes typical of recalcitrant SOC degradation and enzyme activities. The CO released and the SOC had a similar C age (6000 to 10,000 years before the present). Our results indicate that N fertilization of crops may enhance CO emissions from deep critical zones to the atmosphere through a previously disregarded mechanism. This provides another reason for markedly improving N management in fertilized agricultural soils.
即使土壤有机碳（SOC）矿化略有增加，也会导致大气 CO 浓度大幅增加。人们普遍认识到，与表层土壤相比，深层关键带（2 至 12 米深）的 SOC 矿化速度更慢，受人为干扰的影响也更小。在这里，我们表明，20 年的氮肥（N）施肥使深层关键带富含硝酸盐，几乎使 SOC 矿化率增加了一倍。这一结果得到了功能基因表达和酶活性的相应增加的支持，这些基因表达和酶活性典型地代表了难降解的 SOC 降解。释放的 CO 和 SOC 具有相似的 C 年龄（距今 6000 至 10000 年）。我们的结果表明，作物的氮肥施肥可能通过以前被忽视的机制增强深层关键带向大气释放 CO。这为明显改善施肥农业土壤中的 N 管理提供了另一个理由。
