Measurement of asymbiotic N2 fixation in Australian agriculture

Unkovich, M.; Baldock, J. A.

doi:10.1016/j.soilbio.2008.08.021

Cited by 65 publications

(30 citation statements)

References 66 publications

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“…These authors presented an average of 4 kg N ha −1 yr −1 . This value is within the range described recently by Unkovich and Baldock (2008) for different types of agro-ecosystems in different climatic regions (including that Mediterranean) of Australia. However, Boring et al (1988) and Unkovich and Baldock (2008) pointed out that levels of N that enter by this process are significantly reduced according to increased intensity and frequency of tillage.…”

Section: Non-symbiotic N Fixation (Free Living)supporting

confidence: 87%

Guidelines for Constructing Nitrogen, Phosphorus, and Potassium Balances in Historical Agricultural Systems

García‐Ruiz

Molina

Guzmán

et al. 2012

Journal of Sustainable Agriculture

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Changes in cropland intensification and extension and their socioeconomic consequences have been a topic mainly investigated by agrarian historians.Results of the nutrient balances of these historical agricultural systems with relatively closed nutrient cycles might have played an important role because long-term sustainability only is achieved when the replacement of nutrients match those harvested. Thus, the analysis of the nutrient balance of specific historical agricultural systems or management practices has been the focus of agrarian historians. However, many of these nutrient balances have failed to take into account specific processes of importance. In this study, we provide a guideline for constructing nitrogen, phosphorus, and potassium balances in historical agroecosystems at both crop and aggregated scales. A rationale for explaining the processes involved and the variables that must be taken into account is provided. We also apply the model for specific crops at a parish scale using a case study from 1752. In addition, Guidelines for Constructing N, P, and K Balances 651 we provide the basis for linking a specific outcome of the nutrient balance with the long-term sustainability of specific crops.

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Section: Non-symbiotic N Fixation (Free Living)supporting

confidence: 87%

Guidelines for Constructing Nitrogen, Phosphorus, and Potassium Balances in Historical Agricultural Systems

García‐Ruiz

Molina

Guzmán

et al. 2012

Journal of Sustainable Agriculture

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“…Simulations using MOBILE-DNDC model (de Bruijn et al 2009) with soil characteristics of Grignon estimated annual emissions ranging between -3.3 and −7.3 kg N-N 2 ha -1 y -1 . Moreover, since there was no legumes in the cropping system, biological fixation should be small, maximum 10 kg N ha -1 y -1 (Unkovich and Baldock 2008).…”

Section: Carbon and Nitrogen Budgetsmentioning

confidence: 99%

Carbon, nitrogen and Greenhouse gases budgets over a four years crop rotation in northern France

et al. 2011

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Croplands mainly act as net sources of the greenhouse gases carbon dioxide (CO₂) and nitrous oxide (N₂O), as well as nitrogen oxide (NO), a precursor of troposheric ozone. We determined the carbon (C) and nitrogen (N) balance of a four-year crop rotation, including maize, wheat, barley and mustard, to provide a base for exploring mitigation options of net emissions. The crop rotation had a positive net ecosystem production (NEP) of 4.4 +/- 0.7 Mg C ha(-1) y(-1) but represented a net source of carbon with a net biome production (NBP) of -1.3 +/- 1.1 Mg C ha(-1) y(-1). The nitrogen balance of the rotation was correlated with the carbon balance and resulted in net loss (-24 +/- 28 kg N ha(-1) y(-1)). The main nitrogen losses were nitrate leaching (-11.7 +/- 1.0 kg N ha(-1) y(-1)) and ammonia volatilization (-9 kg N ha(-1) y(-1)). Dry and wet depositions were 6.7 +/- 3.0 and 5.9 +/- 0.1 kg N ha(-1) y(-1), respectively. Fluxes of nitrous (N₂O) and nitric (NO) oxides did not contribute significantly to the N budget (N₂O: -1.8 +/- 0.04; NO: -0.7 +/- 0.04 kg N ha(-1) y(-1)) but N₂O fluxes equaled 16% of the total greenhouse gas balance. The link between the carbon and nitrogen balances are discussed. Longer term experiments would be necessary to capture the trends in the carbon and nitrogen budgets within the variability of agricultural ecosystems

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“…Plants were grown as described in Clarke et al (2015) and fertilized once a week with a nitrogen-free B&D nutrient solution (Broughton and Dilworth 1971). Nitrogenase activity in nodules was assessed using an acetylene reduction assay as described by Unkovich et al (2008).…”

Section: Methodsmentioning

confidence: 99%

Soybean Yellow Stripe-like7 is a symbiosome membrane peptide transporter essential for nitrogen fixation

Gavrin

Loughlin

Brear

et al. 2020

Preprint

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Legumes form a symbiosis with rhizobia that convert atmospheric nitrogen (N2) to ammonia which they provide to the plant in return for a carbon and nutrient supply. Nodules, developed as part of the symbiosis, harbor rhizobia which are enclosed in the plant-derived symbiosome membrane (SM), to form a symbiosome. In the mature nodule all exchanges between the symbionts occur across the SM. Here we characterize GmYSL7, a member of Yellow stripe-like family which is localized to the SM in soybean nodules. It is expressed specifically in nodule infected cells with expression peaking soon after nitrogenase becomes active. Although most members of the family transport metal complexed with phytosiderophores, GmYSL7 does not. It transports oligopeptides of between four and 12 amino acids. Silencing of GmYSL7 reduces nitrogenase activity and blocks development when symbiosomes contain a single bacteroid. RNAseq of nodules in which GmYSL7 is silenced suggests that the plant initiates a defense response against the rhizobia. There is some evidence that metal transport in the nodules is dysregulated, with upregulation of genes encoding ferritin and vacuolar iron transporter family and downregulation of a gene encoding nicotianamine synthase. However, it is not clear whether the changes are a result of the reduction of nitrogen fixation and the requirement to store excess iron or an indication of a role of GmYSL7 in regulation of metal transport in the nodules. Further work to identify the physiological substrate for GmYSL7 will allow clarification of this role.One sentence summaryGmYSL7 is a symbiosome membrane peptide transporter that is essential for symbiotic nitrogen fixation that when silenced blocks symbiosome development.

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Measurement of asymbiotic N2 fixation in Australian agriculture

Cited by 65 publications

References 66 publications

Guidelines for Constructing Nitrogen, Phosphorus, and Potassium Balances in Historical Agricultural Systems

Guidelines for Constructing Nitrogen, Phosphorus, and Potassium Balances in Historical Agricultural Systems

Carbon, nitrogen and Greenhouse gases budgets over a four years crop rotation in northern France

Soybean Yellow Stripe-like7 is a symbiosome membrane peptide transporter essential for nitrogen fixation

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