Cargando…

Tightly-Coupled Plant-Soil Nitrogen Cycling: Comparison of Organic Farms across an Agricultural Landscape

How farming systems supply sufficient nitrogen (N) for high yields but with reduced N losses is a central challenge for reducing the tradeoffs often associated with N cycling in agriculture. Variability in soil organic matter and management of organic farms across an agricultural landscape may yield...

Descripción completa

Detalles Bibliográficos
Autores principales: Bowles, Timothy M., Hollander, Allan D., Steenwerth, Kerri, Jackson, Louise E.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4487741/
https://www.ncbi.nlm.nih.gov/pubmed/26121264
http://dx.doi.org/10.1371/journal.pone.0131888
_version_ 1782379043844259840
author Bowles, Timothy M.
Hollander, Allan D.
Steenwerth, Kerri
Jackson, Louise E.
author_facet Bowles, Timothy M.
Hollander, Allan D.
Steenwerth, Kerri
Jackson, Louise E.
author_sort Bowles, Timothy M.
collection PubMed
description How farming systems supply sufficient nitrogen (N) for high yields but with reduced N losses is a central challenge for reducing the tradeoffs often associated with N cycling in agriculture. Variability in soil organic matter and management of organic farms across an agricultural landscape may yield insights for improving N cycling and for evaluating novel indicators of N availability. We assessed yields, plant-soil N cycling, and root expression of N metabolism genes across a representative set of organic fields growing Roma-type tomatoes (Solanum lycopersicum L.) in an intensively-managed agricultural landscape in California, USA. The fields spanned a three-fold range of soil carbon (C) and N but had similar soil types, texture, and pH. Organic tomato yields ranged from 22.9 to 120.1 Mg ha(-1) with a mean similar to the county average (86.1 Mg ha(-1)), which included mostly conventionally-grown tomatoes. Substantial variability in soil inorganic N concentrations, tomato N, and root gene expression indicated a range of possible tradeoffs between yields and potential for N losses across the fields. Fields showing evidence of tightly-coupled plant-soil N cycling, a desirable scenario in which high crop yields are supported by adequate N availability but low potential for N loss, had the highest total and labile soil C and N and received organic matter inputs with a range of N availability. In these fields, elevated expression of a key gene involved in root N assimilation, cytosolic glutamine synthetase GS1, confirmed that plant N assimilation was high even when inorganic N pools were low. Thus tightly-coupled N cycling occurred on several working organic farms. Novel combinations of N cycling indicators (i.e. inorganic N along with soil microbial activity and root gene expression for N assimilation) would support adaptive management for improved N cycling on organic as well as conventional farms, especially when plant-soil N cycling is rapid.
format Online
Article
Text
id pubmed-4487741
institution National Center for Biotechnology Information
language English
publishDate 2015
publisher Public Library of Science
record_format MEDLINE/PubMed
spelling pubmed-44877412015-07-02 Tightly-Coupled Plant-Soil Nitrogen Cycling: Comparison of Organic Farms across an Agricultural Landscape Bowles, Timothy M. Hollander, Allan D. Steenwerth, Kerri Jackson, Louise E. PLoS One Research Article How farming systems supply sufficient nitrogen (N) for high yields but with reduced N losses is a central challenge for reducing the tradeoffs often associated with N cycling in agriculture. Variability in soil organic matter and management of organic farms across an agricultural landscape may yield insights for improving N cycling and for evaluating novel indicators of N availability. We assessed yields, plant-soil N cycling, and root expression of N metabolism genes across a representative set of organic fields growing Roma-type tomatoes (Solanum lycopersicum L.) in an intensively-managed agricultural landscape in California, USA. The fields spanned a three-fold range of soil carbon (C) and N but had similar soil types, texture, and pH. Organic tomato yields ranged from 22.9 to 120.1 Mg ha(-1) with a mean similar to the county average (86.1 Mg ha(-1)), which included mostly conventionally-grown tomatoes. Substantial variability in soil inorganic N concentrations, tomato N, and root gene expression indicated a range of possible tradeoffs between yields and potential for N losses across the fields. Fields showing evidence of tightly-coupled plant-soil N cycling, a desirable scenario in which high crop yields are supported by adequate N availability but low potential for N loss, had the highest total and labile soil C and N and received organic matter inputs with a range of N availability. In these fields, elevated expression of a key gene involved in root N assimilation, cytosolic glutamine synthetase GS1, confirmed that plant N assimilation was high even when inorganic N pools were low. Thus tightly-coupled N cycling occurred on several working organic farms. Novel combinations of N cycling indicators (i.e. inorganic N along with soil microbial activity and root gene expression for N assimilation) would support adaptive management for improved N cycling on organic as well as conventional farms, especially when plant-soil N cycling is rapid. Public Library of Science 2015-06-29 /pmc/articles/PMC4487741/ /pubmed/26121264 http://dx.doi.org/10.1371/journal.pone.0131888 Text en https://creativecommons.org/publicdomain/zero/1.0/ This is an open-access article distributed under the terms of the Creative Commons Public Domain declaration, which stipulates that, once placed in the public domain, this work may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose.
spellingShingle Research Article
Bowles, Timothy M.
Hollander, Allan D.
Steenwerth, Kerri
Jackson, Louise E.
Tightly-Coupled Plant-Soil Nitrogen Cycling: Comparison of Organic Farms across an Agricultural Landscape
title Tightly-Coupled Plant-Soil Nitrogen Cycling: Comparison of Organic Farms across an Agricultural Landscape
title_full Tightly-Coupled Plant-Soil Nitrogen Cycling: Comparison of Organic Farms across an Agricultural Landscape
title_fullStr Tightly-Coupled Plant-Soil Nitrogen Cycling: Comparison of Organic Farms across an Agricultural Landscape
title_full_unstemmed Tightly-Coupled Plant-Soil Nitrogen Cycling: Comparison of Organic Farms across an Agricultural Landscape
title_short Tightly-Coupled Plant-Soil Nitrogen Cycling: Comparison of Organic Farms across an Agricultural Landscape
title_sort tightly-coupled plant-soil nitrogen cycling: comparison of organic farms across an agricultural landscape
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4487741/
https://www.ncbi.nlm.nih.gov/pubmed/26121264
http://dx.doi.org/10.1371/journal.pone.0131888
work_keys_str_mv AT bowlestimothym tightlycoupledplantsoilnitrogencyclingcomparisonoforganicfarmsacrossanagriculturallandscape
AT hollanderalland tightlycoupledplantsoilnitrogencyclingcomparisonoforganicfarmsacrossanagriculturallandscape
AT steenwerthkerri tightlycoupledplantsoilnitrogencyclingcomparisonoforganicfarmsacrossanagriculturallandscape
AT jacksonlouisee tightlycoupledplantsoilnitrogencyclingcomparisonoforganicfarmsacrossanagriculturallandscape