Global agriculture and nitrous oxide emissions

Reay, Dave; Davidson, Eric A.; Smith, K. A.; Smith, Pete; Melillo, Jerry M.; Dentener, Frank; Crutzen, Paul J.

doi:10.1038/nclimate1458

Cited by 788 publications

(472 citation statements)

References 61 publications

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“…We compute the global N 2 O emitted per area covered by crop or pasture in the year 2000 using these estimates. Our estimate for year 2010 N 2 O emissions from agriculture, 4.3 TgN (N 2 O) yr −1 , is at the lower end of previously reported values compiled by Reay et al (2012), ranging from 4.2 to 7 TgN (N 2 O) yr −1 . The year 2000 ratios of emission per area are applied to future changes in crop or pasture area to compute future LULCC N 2 O emissions for all scenarios.…”

Section: N 2 O Emissionsmentioning

confidence: 54%

Potential climate forcing of land use and land cover change

2014

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Abstract. Pressure on land resources is expected to increase as global population continues to climb and the world becomes more affluent, swelling the demand for food. Changing climate may exert additional pressures on natural lands as present-day productive regions may shift, or soil quality may degrade, and the recent rise in demand for biofuels increases competition with edible crops for arable land. Given these projected trends there is a need to understand the global climate impacts of land use and land cover change (LULCC). Here we quantify the climate impacts of global LULCC in terms of modifications to the balance between incoming and outgoing radiation at the top of the atmosphere (radiative forcing, RF) that are caused by changes in long-lived and short-lived greenhouse gas concentrations, aerosol effects, and land surface albedo. We attribute historical changes in terrestrial carbon storage, global fire emissions, secondary organic aerosol emissions, and surface albedo to LULCC using simulations with the Community Land Model version 3.5. These LULCC emissions are combined with estimates of agricultural emissions of important trace gases and mineral dust in two sets of Community Atmosphere Model simulations to calculate the RF of changes in atmospheric chemistry and aerosol concentrations attributed to LULCC. With all forcing agents considered together, we show that 40 % (±16 %) of the present-day anthropogenic RF can be attributed to LULCC. Changes in the emission of non-CO 2 greenhouse gases and aerosols from LULCC enhance the total LULCC RF by a factor of 2 to 3 with respect to the LULCC RF from CO 2 alone. This enhancement factor also applies to projected LULCC RF, which we compute for four future scenarios associated with the Representative Concentration Pathways. We attribute total RFs between 0.9 and 1.9 W m −2 to LULCC for the year 2100 (relative to a preindustrial state). To place an upper bound on the potential of LULCC to alter the global radiation budget, we include a fifth scenario in which all arable land is cultivated by 2100. This theoretical extreme case leads to a LULCC RF of 3.9 W m −2 (±0.9 W m −2 ), suggesting that not only energy policy but also land policy is necessary to minimize future increases in RF and associated climate changes.

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Section: N 2 O Emissionsmentioning

confidence: 54%

Potential climate forcing of land use and land cover change

2014

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“…In particular, this change would likely lower emission estimates from regions predominantly fertilized at low N inputs while increasing emission estimates from highly fertilized areas. Using a constant EF may explain why regional bottom-up estimates of N 2 O emissions are inconsistent with top-down estimates (18,22,23).…”

Section: Discussionmentioning

confidence: 99%

“…Grace et al (19) animal manure (21), yield an overall EF of 4 ± 1% (17,18). Although bottom-up models are in broad agreement (22), there are large uncertainties and the agreement breaks down at regional and subregional scales (23). The use of EFs that vary with N input may help to reconcile this difference and guide policies that are urgently needed to curb the projected 20% increase in agricultural N 2 O emissions expected by 2030 (23).…”

mentioning

confidence: 99%

Global metaanalysis of the nonlinear response of soil nitrous oxide (N ₂ O) emissions to fertilizer nitrogen

Shcherbak

Millar

Robertson

2014

Proc. Natl. Acad. Sci. U.S.A.

835

536

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Nitrous oxide (N 2 O) is a potent greenhouse gas (GHG) that also depletes stratospheric ozone. Nitrogen (N) fertilizer rate is the best single predictor of N 2 O emissions from agricultural soils, which are responsible for ∼50% of the total global anthropogenic flux, but it is a relatively imprecise estimator. Accumulating evidence suggests that the emission response to increasing N input is exponential rather than linear, as assumed by Intergovernmental Panel on Climate Change methodologies. We performed a metaanalysis to test the generalizability of this pattern. From 78 published studies (233 site-years) with at least three N-input levels, we calculated N 2 O emission factors (EFs) for each nonzero input level as a percentage of N input converted to N 2 O emissions. We found that the N 2 O response to N inputs grew significantly faster than linear for synthetic fertilizers and for most crop types. N-fixing crops had a higher rate of change in EF (ΔEF) than others. A higher ΔEF was also evident in soils with carbon >1.5% and soils with pH <7, and where fertilizer was applied only once annually. Our results suggest a general trend of exponentially increasing N 2 O emissions as N inputs increase to exceed crop needs. Use of this knowledge in GHG inventories should improve assessments of fertilizer-derived N 2 O emissions, help address disparities in the global N 2 O budget, and refine the accuracy of N 2 O mitigation protocols. In low-input systems typical of sub-Saharan Africa, for example, modest N additions will have little impact on estimated N 2 O emissions, whereas equivalent additions (or reductions) in excessively fertilized systems will have a disproportionately major impact.fertilizer response | greenhouse gas emissions | agriculture | bioenergy | greenhouse gas mitigation

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“…For instance, the demand for meat and other animal products (e.g., eggs, milk, and cheese) in developing countries is expected to double by 2050 (Garnett 2009), and satisfying this rising demand will be a substantial challenge for the livestock sector (FAO 2005;Valin et al 2013). In fact, a number of studies have analyzed the GHG implications of global increasing demand for livestock (e.g., Naylor et al 2005;Reay et al 2012;Bustamante et al 2012), anticipating, for instance, that CH 4 emissions from enteric fermentation could increase by 31 % between 1990 and 2030 and that N 2 O emissions from manure management could increase by 20 % mainly due to developing countries (EPA 2011). Inventories that resolve livestock emissions in time and space are therefore important to efforts to cost-effectively reduce GHG emissions.…”

mentioning

confidence: 99%