Cover crops and fertilization alter nitrogen loss in organic and conventional conservation agriculture systems

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38 Scopus citations

Abstract

Agroecosystem nitrogen (N) loss produces greenhouse gases, induces eutrophication, and is costly for farmers; therefore, conservation agricultural management practices aimed at reducing N loss are increasingly adopted. However, the ecosystem consequences of these practices have not been well-studied. We quantified N loss via leaching, NH3 volatilization, N2 O emissions, and N retention in plant and soil pools of corn conservation agroecosystems in Kentucky, USA. Three systems were evaluated: (1) an unfertilized, organic system with cover crops hairy vetch (Vicia villosa), winter wheat (Triticum aestivum), or a mix of the two (bi-culture); (2) an organic system with a hairy vetch cover crop employing three fertilization schemes (0N, organic N, or a fertilizer N-credit approach); and (3) a conventional system with a winter wheat cover crop and three fertilization schemes (0N, urea N, or organic N). In the unfertilized organic system, cover crop species affected NO3 -N leaching (vetch > bi-culture > wheat) and N2 O-N emissions and yield during corn growth (vetch, bi-culture > wheat). Fertilization increased soil inorganic N, gaseous Nloss, Nleaching, and yield in the organic vetch and conventional wheat systems. Fertilizer scheme affectedthe magnitude of growing season N2 O-N loss in the organic vetch system (organic N > fertilizer N-credit) and the timing of loss (organic N delayed N2 O-N loss vs. urea) and NO3 -N leaching (urea >> organic N) in the conventional wheat system, but had no effect on yield. Cover crop selection and N fertilization techniques can reduce N leaching and greenhouse gas emissions without sacrificing yield, thereby enhancing N conservation in both organic and conventional conservation agriculture systems.

Original languageEnglish
Article number2260
JournalFrontiers in Plant Science
Volume8
DOIs
StatePublished - Jan 22 2018

Bibliographical note

Funding Information:
We thank and acknowledge the funding provided by the University of Kentucky Department of Plant and Soil Sciences, the Kentucky Agriculture Experiment Station, and the Karri Casner Environmental Sciences Fellowship for supporting this work.

Publisher Copyright:
© 2018 Shelton, Jacobsen and McCulley.

Keywords

  • Ammonia volatilization
  • Conservation agriculture
  • Cover crops
  • Nitrate leaching
  • Nitrous oxide emissions

ASJC Scopus subject areas

  • Plant Science

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