Veerman Liz, Kalbitz Karsten, Schoorl Jorien C, Tietema Albert
a Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam (UvA) , Amsterdam , Netherlands.
b Institute of Soil Science and Site Ecology, Technical University Dresden , Dresden , Germany.
Isotopes Environ Health Stud. 2018 Mar;54(1):16-27. doi: 10.1080/10256016.2017.1352586. Epub 2017 Jul 27.
We investigated the transfer of N into the soil via N uptake and release by tree roots, which involves the principles of the split-root technique. One half of the root system received an injection of (NH)SO and the other half equivalent amounts of (NH)SO at N natural abundance level. N was transferred from one side of the root system (N side) to the other side (N side) and released into the soil. The method was conducted with Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] Karst). Two concentration levels of (NH)SO were used, corresponding with annual N deposition in the Netherlands (30 kg N ha) and a twelfth of that (2.5 kg N ha). Samples were taken 3 and 6 weeks after labelling and divided into needles + stem, roots, rhizosphere and bulk soil. Already 3 weeks after labelling, Scots pine took up 23.7 % of the low and 9.1 % of the high amounts of N, while Norway spruce took up 21.5 and 32.1 %, respectively. Both species transported proportions of N to the rhizosphere (0.1-0.2 %) and bulk soil (0.3-0.9 %). The method is a useful tool to investigate the fate of root-derived N in soils, for example, for the formation of stable forms of soil organic matter.
我们研究了氮通过树木根系的吸收和释放进入土壤的过程，这涉及到分根技术的原理。根系的一半接受硫酸铵注射，另一半接受天然丰度水平的等量硫酸铵。氮从根系的一侧（氮侧）转移到另一侧（氮侧）并释放到土壤中。该方法以苏格兰松（Pinus sylvestris L.）和挪威云杉（Picea abies [L.] Karst）进行。使用了两个硫酸铵浓度水平，分别对应荷兰的年氮沉降量（30 kg N ha）及其十二分之一（2.5 kg N ha）。在标记后3周和6周取样，并分为针叶+茎、根、根际和大块土壤。标记后仅3周，苏格兰松吸收了低量氮的23.7%和高量氮的9.1%，而挪威云杉分别吸收了21.5%和32.1%。两个物种都将一定比例的氮运输到根际（0.1 - 0.2%）和大块土壤（0.3 - 0.9%）。该方法是研究土壤中根系来源氮去向的有用工具，例如用于土壤有机质稳定形式的形成。
