Evaluating the importance of a potential source of error when applying shoot 15N labelling techniques to legumes to quantify the below-ground transfer of nitrogen to other species

Matthew Gardner, Mark Peoples, Jason Condon, Guangdi Li, Mark Conyers, Brian Dear

Research output: Book chapter/Published conference paperConference paper

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Abstract

Different 15N-based shoot-labelling protocols have been utilised to quantify the below-ground transfer of N between pasture or crop species. The most straight forward and effective 15N-labelling technique appears to be shoot labelling via leaflets or petioles. This paper reports a time-course study following 15N-shoot labelling of pasture legumes to ascertain whether a pulse-feeding of 15N labelled urea to the leaf resulted in induced exudation of highly 15N enriched compounds from the roots into the surrounding soil. Such an occurrence could confound interpretation of 15N data used to measure transfer of N between legume and non legume species. Small quantities of highly enriched 15N (99.8 atom% 15N) urea were fed to leaves of subterranean clover (Trifolium subteraneum; 0.22ml/plant of 1% urea solution) and lucerne (Medicago sativa; 0.45ml of 1% urea solution) over a period of 3 days. On days 1, 2, 4, 8, 16 and 32 after labelling, the plants were harvested and the 15N enrichment of shoots, roots and soil was determined. Soil analyses showed that the 15N enrichment of soil N was significantly higher in the lucerne treatment (12.3 '; parts per thousand 15N relative to the 15N content of atmospheric N2, 0.3663 atom% 15N) than subclover (11.3 ') (P<0.05), and both levels were significantly higher than, but very close to, the background level in the soil (10.7 '). The results could be explained if <10% of the lucerne root N or 12-27% of the subclover roots remained unrecovered in the soil following the sieving process. It was concluded that pulse-feeding of high concentrations of 15N labelled urea in the leaf did not induce substantial exudation of highly 15N enriched compounds from the roots into the surrounding soil.
Original languageEnglish
Title of host publication16th AAC
Subtitle of host publicationCapturing opportunities and overcoming obstacles in Australian agronomy
EditorsI. Yunusa
Place of PublicationAustralia
PublisherThe Regional Institute
Pages1-4
Number of pages4
Publication statusPublished - 2012
EventAustralian Agronomy Conference - University of New England, Armidale, Australia
Duration: 14 Oct 201218 Oct 2012
Conference number: 16th
http://agronomyaustraliaproceedings.org/index.php/2012-conf-proc-homepage (Conference proceedings 2012 homepage)

Conference

ConferenceAustralian Agronomy Conference
Abbreviated titleCapturing Opportunities and Overcoming Obstacles in Australian Agronomy
CountryAustralia
CityArmidale
Period14/10/1218/10/12
Internet address

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labeling techniques
legumes
shoots
urea
nitrogen
soil
alfalfa
exudation
leaves
Trifolium
Trifolium subterraneum
sieving
forage legumes
petioles
Medicago sativa
pastures
crops

Cite this

Gardner, M., Peoples, M., Condon, J., Li, G., Conyers, M., & Dear, B. (2012). Evaluating the importance of a potential source of error when applying shoot 15N labelling techniques to legumes to quantify the below-ground transfer of nitrogen to other species. In I. Yunusa (Ed.), 16th AAC: Capturing opportunities and overcoming obstacles in Australian agronomy (pp. 1-4). Australia: The Regional Institute.
Gardner, Matthew ; Peoples, Mark ; Condon, Jason ; Li, Guangdi ; Conyers, Mark ; Dear, Brian. / Evaluating the importance of a potential source of error when applying shoot 15N labelling techniques to legumes to quantify the below-ground transfer of nitrogen to other species. 16th AAC: Capturing opportunities and overcoming obstacles in Australian agronomy. editor / I. Yunusa. Australia : The Regional Institute, 2012. pp. 1-4
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abstract = "Different 15N-based shoot-labelling protocols have been utilised to quantify the below-ground transfer of N between pasture or crop species. The most straight forward and effective 15N-labelling technique appears to be shoot labelling via leaflets or petioles. This paper reports a time-course study following 15N-shoot labelling of pasture legumes to ascertain whether a pulse-feeding of 15N labelled urea to the leaf resulted in induced exudation of highly 15N enriched compounds from the roots into the surrounding soil. Such an occurrence could confound interpretation of 15N data used to measure transfer of N between legume and non legume species. Small quantities of highly enriched 15N (99.8 atom{\%} 15N) urea were fed to leaves of subterranean clover (Trifolium subteraneum; 0.22ml/plant of 1{\%} urea solution) and lucerne (Medicago sativa; 0.45ml of 1{\%} urea solution) over a period of 3 days. On days 1, 2, 4, 8, 16 and 32 after labelling, the plants were harvested and the 15N enrichment of shoots, roots and soil was determined. Soil analyses showed that the 15N enrichment of soil N was significantly higher in the lucerne treatment (12.3 '; parts per thousand 15N relative to the 15N content of atmospheric N2, 0.3663 atom{\%} 15N) than subclover (11.3 ') (P<0.05), and both levels were significantly higher than, but very close to, the background level in the soil (10.7 '). The results could be explained if <10{\%} of the lucerne root N or 12-27{\%} of the subclover roots remained unrecovered in the soil following the sieving process. It was concluded that pulse-feeding of high concentrations of 15N labelled urea in the leaf did not induce substantial exudation of highly 15N enriched compounds from the roots into the surrounding soil.",
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Gardner, M, Peoples, M, Condon, J, Li, G, Conyers, M & Dear, B 2012, Evaluating the importance of a potential source of error when applying shoot 15N labelling techniques to legumes to quantify the below-ground transfer of nitrogen to other species. in I Yunusa (ed.), 16th AAC: Capturing opportunities and overcoming obstacles in Australian agronomy. The Regional Institute, Australia, pp. 1-4, Australian Agronomy Conference, Armidale, Australia, 14/10/12.

Evaluating the importance of a potential source of error when applying shoot 15N labelling techniques to legumes to quantify the below-ground transfer of nitrogen to other species. / Gardner, Matthew; Peoples, Mark; Condon, Jason; Li, Guangdi; Conyers, Mark; Dear, Brian.

16th AAC: Capturing opportunities and overcoming obstacles in Australian agronomy. ed. / I. Yunusa. Australia : The Regional Institute, 2012. p. 1-4.

Research output: Book chapter/Published conference paperConference paper

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T1 - Evaluating the importance of a potential source of error when applying shoot 15N labelling techniques to legumes to quantify the below-ground transfer of nitrogen to other species

AU - Gardner, Matthew

AU - Peoples, Mark

AU - Condon, Jason

AU - Li, Guangdi

AU - Conyers, Mark

AU - Dear, Brian

N1 - Imported on 03 May 2017 - DigiTool details were: 086 FoR could not be migrated (25 - ). publisher = Australia: The Regional Institute, 2012. editor/s (773b) = I Yunusa; Event dates (773o) = 14-18 October 2012; Parent title (773t) = Australian Agronomy Conference.

PY - 2012

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N2 - Different 15N-based shoot-labelling protocols have been utilised to quantify the below-ground transfer of N between pasture or crop species. The most straight forward and effective 15N-labelling technique appears to be shoot labelling via leaflets or petioles. This paper reports a time-course study following 15N-shoot labelling of pasture legumes to ascertain whether a pulse-feeding of 15N labelled urea to the leaf resulted in induced exudation of highly 15N enriched compounds from the roots into the surrounding soil. Such an occurrence could confound interpretation of 15N data used to measure transfer of N between legume and non legume species. Small quantities of highly enriched 15N (99.8 atom% 15N) urea were fed to leaves of subterranean clover (Trifolium subteraneum; 0.22ml/plant of 1% urea solution) and lucerne (Medicago sativa; 0.45ml of 1% urea solution) over a period of 3 days. On days 1, 2, 4, 8, 16 and 32 after labelling, the plants were harvested and the 15N enrichment of shoots, roots and soil was determined. Soil analyses showed that the 15N enrichment of soil N was significantly higher in the lucerne treatment (12.3 '; parts per thousand 15N relative to the 15N content of atmospheric N2, 0.3663 atom% 15N) than subclover (11.3 ') (P<0.05), and both levels were significantly higher than, but very close to, the background level in the soil (10.7 '). The results could be explained if <10% of the lucerne root N or 12-27% of the subclover roots remained unrecovered in the soil following the sieving process. It was concluded that pulse-feeding of high concentrations of 15N labelled urea in the leaf did not induce substantial exudation of highly 15N enriched compounds from the roots into the surrounding soil.

AB - Different 15N-based shoot-labelling protocols have been utilised to quantify the below-ground transfer of N between pasture or crop species. The most straight forward and effective 15N-labelling technique appears to be shoot labelling via leaflets or petioles. This paper reports a time-course study following 15N-shoot labelling of pasture legumes to ascertain whether a pulse-feeding of 15N labelled urea to the leaf resulted in induced exudation of highly 15N enriched compounds from the roots into the surrounding soil. Such an occurrence could confound interpretation of 15N data used to measure transfer of N between legume and non legume species. Small quantities of highly enriched 15N (99.8 atom% 15N) urea were fed to leaves of subterranean clover (Trifolium subteraneum; 0.22ml/plant of 1% urea solution) and lucerne (Medicago sativa; 0.45ml of 1% urea solution) over a period of 3 days. On days 1, 2, 4, 8, 16 and 32 after labelling, the plants were harvested and the 15N enrichment of shoots, roots and soil was determined. Soil analyses showed that the 15N enrichment of soil N was significantly higher in the lucerne treatment (12.3 '; parts per thousand 15N relative to the 15N content of atmospheric N2, 0.3663 atom% 15N) than subclover (11.3 ') (P<0.05), and both levels were significantly higher than, but very close to, the background level in the soil (10.7 '). The results could be explained if <10% of the lucerne root N or 12-27% of the subclover roots remained unrecovered in the soil following the sieving process. It was concluded that pulse-feeding of high concentrations of 15N labelled urea in the leaf did not induce substantial exudation of highly 15N enriched compounds from the roots into the surrounding soil.

KW - Open access version available

KW - 15N shoot labelling

KW - Lucerne

KW - N transfer

KW - Nitrogen

KW - Soil

KW - Subterranean Clover

M3 - Conference paper

SP - 1

EP - 4

BT - 16th AAC

A2 - Yunusa, I.

PB - The Regional Institute

CY - Australia

ER -

Gardner M, Peoples M, Condon J, Li G, Conyers M, Dear B. Evaluating the importance of a potential source of error when applying shoot 15N labelling techniques to legumes to quantify the below-ground transfer of nitrogen to other species. In Yunusa I, editor, 16th AAC: Capturing opportunities and overcoming obstacles in Australian agronomy. Australia: The Regional Institute. 2012. p. 1-4