The myth of nitrogen fertilization for soil carbon sequestration.

By S. Khan, R. Mulvaney, T. Ellsworth, C. Boast. Journal of Environmental Quality, 2007

751 citations recorded by the source corpus.

Intensive use of N fertilizers in modern agriculture is motivated by the economic value of high grain yields and is generally perceived to sequester soil organic C by increasing the input of crop residues. This perception is at odds with a century of soil organic C data reported herein for the Morrow Plots, the world's oldest experimental site under continuous corn (Zea mays L.). After 40 to 50 yr of synthetic fertilization that exceeded grain N removal by 60 to 190%, a net decline occurred in soil C despite increasingly massive residue C incorporation, the decline being more extensive for a corn-soybean (Glycine max L. Merr.) or corn-oats (Avena sativa L.)-hay rotation than for continuous corn and of greater intensity for the profile (0-46 cm) than the surface soil. These findings implicate fertilizer N in promoting the decomposition of crop residues and soil organic matter and are consistent with data from numerous cropping experiments involving synthetic N fertilization in the USA Corn Belt and elsewhere, although not with the interpretation usually provided. There are important implications for soil C sequestration because the yield-based input of fertilizer N has commonly exceeded grain N removal for corn production on fertile soils since the 1960s. To mitigate the ongoing consequences of soil deterioration, atmospheric CO(2) enrichment, and NO(3)(-) pollution of ground and surface waters, N fertilization should be managed by site-specific assessment of soil N availability. Current fertilizer N management practices, if combined with corn stover removal for bioenergy production, exacerbate soil C loss.

Subfields: Ecology, Environmental Chemistry, Soil Science

View Paper: https://www.semanticscholar.org/paper/8c7072032538c84201e43d1f78caa61dc49cb698

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Citations in the corpus

Tillage and Crop Rotation Effects on Corn Agronomic Response and Economic Return at Seven Iowa Locations (2015, neutral): “, 2013) and in the long-term by affecting soil organic matter dynamics (Conant et al., 2007; Khan et al., 2007; Al-Kaisi et al., 2005).”
Does the combined application of organic and mineral nutrient sources influence maize productivity? A meta-analysis (2011, positive): “This is likely because the added N fertilizers enhanced decomposition of the added OR, which likely resulted in greater N supply but also greater losses of added C (Khan et al. 2007; Nardi et al. 2004).”
Erratum to The chemical and functional characterization of soil N and its biotic components (2009, background): “It is also the basis of present discussions, in present climate change policy, as to whether N additions and added plant residues result in the sequestration of soil C (Khan et al., 2007).”
Soils and food sufficiency. A review (2011, background): “Addition of N may increase the soil C pool in N-deficient soils (Jaycinthe et al., 2002; Jagdemme et al., 2008), or decrease it while enhancing mineralization in others (Khan et al., 2007).”
Precision Agriculture Technologies positively contributing to GHG emissions mitigation, farm productivity and economics (2017, positive): “The application of precision agriculture (PA) practices, using the large reservoir of Precision Agriculture Technologies (PATs) in agricultural field operations could positively contribute to GHG emission reduction due to: (i) the enhancement of the ability of soils to operate as carbon stock reserv”
Mechanisms of Nitrogen Use in Maize (2019, background): “The application of inorganic N fertilizers has been associated with loss of soil organic carbon through enhanced respiration and greenhouse gas emissions [141,142].”
Modeling Carbon Sequestration in Home Lawns (2011, background): “Soil emissions of CO2, methane (CH4), and nitrous oxide (N2O) are highly impacted by soil properties and climate (Kaye et al., 2005; Khan et al., 2007; Maggiotto et al., 2000; Smith et al., 2007a).”
Biofuel Impacts on World Food Supply: Use of Fossil Fuel, Land and Water Resources (2008, background): “However, after a 40 to 50 year application of synthetic nitrogen fertilize r in Illinois, a net decline occurred in soil carbon des pite the massive residue incorporation into the soi l [163].”