Natural Potassium (K) Isotope Fractionation during Corn Growth and Quantification of K Fertilizer Recovery Efficiency Using Stable K Isotope Labeling
Natural Potassium (K) Isotope Fractionation during Corn Growth and Quantification of K Fertilizer Recovery Efficiency Using Stable K Isotope Labeling
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DOI：
10.1021/acsearthspacechem.2c00105
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发表时间：
2022-07
影响因子：
3.4
通讯作者：
Xin-Yang Chen;Xin-Yuan Zheng;B. Beard;M. Urrutia;C. Johnson;P. Barak
中科院分区：
文献类型：
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作者：
Xin-Yang Chen;Xin-Yuan Zheng;B. Beard;M. Urrutia;C. Johnson;P. Barak
加深对土壤-植物系统中钾 (K) 循环的了解具有科学和经济意义，但基于钾浓度测量的传统研究存在一些已知的局限性。最近出现的高精度稳定钾同位素分析（报告为 δ41K 值）可以促进使用稳定钾同位素标记和质量依赖性同位素分馏来研究钾养分循环，包括钾肥利用和植物-土壤相互作用。作为概念验证，我们进行了一项盆栽研究来量化玉米对钾肥的吸收。使用预混有不同量 41K 标记肥料的土壤进行三组处理（50、100、200 mg K kg-1 土壤）。对照组使用相同的土壤，未经肥料处理。 〜6周后对地上芽和土壤进行取样和分析。对照组显示玉米优先吸收轻 K 同位素，在 41K/39K 中芽和土壤之间估计质量依赖性分馏为 ∼−0.37‰ (±0.23‰)。在使用富集 41K 示踪剂的施肥实验中，δ41K 数据明确量化了玉米芽中肥料来源的钾，产生了 59-81% 的表观肥料回收效率。相比之下，基于钾浓度的方法低估了低钾处理的肥料利用率，高估了高钾处理的肥料利用率，因为它无法区分不同的钾源，这些钾源对土壤中生物可利用钾库的相对贡献可能会因植物与土壤的相互作用而变化。我们的研究证明了稳定钾同位素在提高对土壤-植物系统钾循环的理解方面的潜力。
An improved understanding of the potassium (K) cycle in soil–plant systems is scientifically and economically significant, but the conventional research based on K concentration measurements has several known limitations. The recent advent of high-precision stable K isotope analysis (reported as δ41K values) can facilitate the use of both stable K isotope labeling and mass-dependent isotopic fractionation in studying the K nutrient cycle, including K fertilizer utilization, and plant–soil interactions. As a proof of concept, we conducted a pot study to quantify the uptake of K fertilizer by corn. Three groups of treatment (50, 100, 200 mg K kg–1soil) were conducted using soils premixed with different amounts of41K-labeled fertilizer. A control group used the same soil without fertilizer treatment. Aboveground shoots and soils were sampled and analyzed after ∼6 weeks. The control group showed preferential uptake of light K isotopes by corn with an estimated mass-dependent fractionation of ∼−0.37‰ (±0.23‰) in41K/39K between the shoot and soil. In fertilized experiments using an enriched41K tracer, δ41K data unambiguously quantifies fertilizer-derived K in corn shoots, yielding apparent fertilizer recovery efficiency of 59–81%. In comparison, the K concentration-based method underestimated fertilizer utilization at low K treatment and overestimated fertilizer utilization at high K treatment because it cannot distinguish different K sources whose relative contributions to the bioavailable K pool in the soil can vary in response to plant–soil interactions. Our study demonstrates the potential of stable K isotopes in improving the understanding of the K cycle in soil–plant systems.