College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
Key Laboratory of Plant Nutrition and the Agri-Environment in Northwest China, MOA, Yangling, Shaanxi 712100, China.
Environ Sci Technol. 2021 May 4;55(9):5782-5790. doi: 10.1021/acs.est.0c06730. Epub 2021 Apr 13.
Additional evidence indicates that the nitrate stored in the deep soil profile has an important role in regulating the global nitrogen (N) cycle. This study assessed the effects of land-use changes from croplands to intensive orchards (LUCO) on N surplus, nitrate accumulation in deep soil, and groundwater quality in the kiwifruit belt of the northern slope region of the Qinling Mountains, China. LUCO resulted in comparatively high N surplus in orchards (282 vs 1206 kg ha yr, respectively). The average nitrate accumulation within the 0-10 m profiles of orchards was 7113 kg N ha, which was equal to approximately the total N surplus of 6 years of the orchards. The total nitrate stock within 0-10 m soil profiles of the kiwifruit belt was 266.5 Gg N, which was 3.5 times higher than the total annual N input. The nitrate concentrations of 97% of groundwater samples exceeded the WHO standard. The LUCO resulted in large nitrate storage in the vadose zone and caused serious contamination of groundwater. Our study highlights that nitrate accumulation in the vadose zone of an intensive land-use system is one of the main fates of surplus N and also a hotspot of nitrate accumulation.
此外的证据表明，深层土壤中储存的硝酸盐在调节全球氮（N）循环方面起着重要作用。本研究评估了从耕地到集约果园（LUCO）的土地利用变化对中国秦岭北坡猕猴桃带氮盈余、深层土壤硝酸盐积累和地下水质量的影响。LUCO 导致果园中氮盈余相对较高（分别为 282 和 1206 kg ha yr）。果园 0-10 m 剖面中硝酸盐的平均积累量为 7113 kg N ha，相当于果园 6 年的总氮盈余。猕猴桃带 0-10 m 土壤剖面中硝酸盐的总储量为 266.5 Gg N，是年总氮输入量的 3.5 倍。97%的地下水样本硝酸盐浓度超过了世界卫生组织的标准。LUCO 导致了土壤包气带中大量硝酸盐的储存，造成了地下水的严重污染。我们的研究强调，集约土地利用系统包气带中硝酸盐的积累是过剩氮的主要归宿之一，也是硝酸盐积累的热点。
