Edy Nur, Yelianti Upik, Irawan Bambang, Polle Andrea, Pena Rodica
Forest Botany and Tree Physiology, University of Goettingen, Göttingen, Germany.
Department of Agrotechnology, Tadulako University, Palu, Indonesia.
Front Plant Sci. 2020 Feb 25;11:92. doi: 10.3389/fpls.2020.00092. eCollection 2020.
Conversion of lowland tropical rainforests to intensely fertilized agricultural land-use systems such as oil palm () plantations leads to changes in nitrogen (N) cycling. Although soil microbial-driven N dynamics has been largely studied, the role of the plant as a major component in N uptake has rarely been considered. We address this gap by comparing the root N contents and uptake in lowland rainforests with that in oil palm plantations on Sumatra, Indonesia. To this aim, we applied N-labeled ammonium to intact soil, measured the N recovery in soil and roots, and calculated the root relative N uptake efficiency for 10 days after label application. We found that root N contents were by one third higher in the rainforest than oil palm plantations. However, N uptake efficiency was similar in the two systems. This finding suggests that lower N contents in oil palm roots were likely caused by plant internal utilization of the absorbed N (e.g., N export to fruit bunches) than by lower ability to take up N from the soil. N recovery in roots was primarily driven by the amount of root biomass, which was higher in oil palm plantation than rainforest. The oil palms unveiled a high capacity to acquire N, offering the possibility of enhancing sustainable plantation management by reducing N fertilizer application.
将低地热带雨林转变为集约化施肥的农业土地利用系统，如油棕种植园，会导致氮（N）循环发生变化。尽管土壤微生物驱动的氮动态已得到大量研究，但植物作为氮吸收主要组成部分的作用却很少被考虑。我们通过比较印度尼西亚苏门答腊低地雨林和油棕种植园的根系氮含量及吸收情况来填补这一空白。为此，我们向完整土壤中施用氮标记的铵盐，测量土壤和根系中的氮回收率，并计算标记施用后10天的根系相对氮吸收效率。我们发现，雨林中的根系氮含量比油棕种植园高1/3。然而，两个系统中的氮吸收效率相似。这一发现表明，油棕根系中较低的氮含量可能是由于植物对吸收的氮进行内部利用（例如氮向果串的输出），而非从土壤中吸收氮的能力较低所致。根系中的氮回收率主要由根系生物量决定，油棕种植园的根系生物量高于雨林。油棕展现出较高的氮获取能力，这为通过减少氮肥施用来加强可持续种植园管理提供了可能性。
