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Evaluation of methods to measure differential 15N labeling of soil and root N pools for studies of root exudation

“…1(a)). Similar to other reports,32, 33, 35, 36, 40, 43, 45 foliar 15 N application resulted in inhomogeneous intra‐plant 15 N distribution, as a large proportion of 15 N remained in the labeled leaf and was not transferred to other plant parts, particularly to roots. Best 15 N‐labeling results were achieved by stem infiltration, reaching 8% APE in shoots and 15% in roots of L. perenne and C. jacea plants.…”

“…Compared with NO or NH, urea offers the advantage of being a non‐polar highly mobile molecule of high N content which is rapidly taken up34, 35 and metabolised to CO 2 and NH by urease, a ubiquitous plant enzyme. Urea solutions were either applied to intact leaves as a fine mist36–40 or as a liquid to leaves that remained intact11, 41, 42 or, in cases where leaf tips, petioles or mid‐veins were cut, these were immersed in tracer solution 34, 35, 43–45. Legume rhizodeposits were also 15 N labeled by exposing root systems to 15 N 2 8, 28, 46…”

Nitrogen rhizodeposition by legumes and its fate in agroecosystems: A field study and literature review

“…Fertilization decreased the top-to-subsoil ratio by 39% for root biomass and 34% for root N. Remarkably, the top-to-subsoil ratio of N rhizodeposition decreased by 62% compared to that ratio of root N, indicating a relatively higher N rhizodeposition release by roots or slower N decomposition within the subsoil (Figure 3). Fertilization decreased the topsoil-to-subsoil ratios of N rhizodeposition by 48-57% compared to those without Arcand, Lemke, Farrell, & Knight, 2014;Hammelehle, Oberson, Lüscher, Mäder, & Mayer, 2018;Hupe et al, 2016;Hupe et al, 2018;Jamont, Piva, & Fustec, 2013;Jensen, 1996;Khan, Peoples, Chalk, & Herridge, 2002;Laberge, Haussmann, Ambus, & Høgh-Jensen, 2011;López-Bellido, Benítez-Vega, García, Redondo, & López-Bellido, 2011;Mahieu et al, 2014;Mahieu, Fustec, Faure, Corre-Hellou, & Crozat, 2007 NPK fertilization (except peanut), which was in accordance with the decreased ratios of root biomass and root N caused by fertilization.…”

“…Three-way interaction effects of fertilization (F: 0 F and + NPK), leguminous specie (L: peanut, soybean, mungbean, and adzuki bean), and soil layer (S: 0-20 cm and 20-40 cm) on N rhizodeposition are conducted, and the statistically significant The solid line and dashed lines indicate the regression line and 95% confidence intervals. Literature data are collected from published articles Arcand, Lemke, Farrell, & Knight, 2014;Hammelehle, Oberson, Lüscher, Mäder, & Mayer, 2018;Hupe et al, 2016;Hupe et al, 2018;Jamont, Piva, & Fustec, 2013;Jensen, 1996;Khan, Peoples, Chalk, & Herridge, 2002;Laberge, Haussmann, Ambus, & Høgh-Jensen, 2011;López-Bellido, Benítez-Vega, García, Redondo, & López-Bellido, 2011;Mahieu et al, 2014;Mahieu, Fustec, Faure, Corre-Hellou, & Crozat, 2007…”

Rhizodeposition through root senescence and root exudation of atmospheric C and N by legumes is controlled by traits indicative of resource acquisition and root development

“…Few studies have been performed to measure simultaneously the rhizodeposition of both C and N (Hupe et al, 2018, 2019; Wichern et al, 2007a, 2007b; 2008; Yasmin et al, 2010). Due to the specific ability of legumes to use atmospheric sources of N and transfer part of it to the soil or companion plants (Høgh‐Jensen & Schjoerring, 2001; Khan et al, 2002; Mc Neill & Fillery, 2008; Paynel & Cliquet, 2003), we chose to measure the rhizodeposition of atmospheric N more specifically. The methodology developed in the present study allows specifically the measurement of C and N fluxes from the atmosphere to the soil under controlled conditions throughout plant growth.…”