title: No tillage and liming reduce greenhouse gas emissions from poorly drained agricultural soils in Mediterranean regions.
abstract: No tillage (NT) has been associated to increased N2O emission from poorly drained agricultural soils. This is the case for soils with a low permeable Bt horizon, which generates a perched water layer after water addition (via rainfall or irrigation) over a long period of time. Moreover, these soils often have problems of acidity and require liming application to sustain crop productivity; changes in soil pH have large implications for the production and consumption of soil greenhouse gas (GHG) emissions. Here, we assessed in a split-plot design the individual and interactive effects of tillage practices (conventional tillage (CT) vs. NT) and liming (Ca-amendment vs. not-amendment) on N2O and CH4 emissions from poorly drained acidic soils, over a field experiment with a rainfed triticale crop. Soil mineral N concentrations, pH, temperature, moisture, water soluble organic carbon, GHG fluxes and denitrification capacity were measured during the experiment. Tillage increased N2O emissions by 68% compared to NT and generally led to higher CH4 emissions; both effects were due to the higher soil moisture content under CT plots. Under CT, liming reduced N2O emissions by 61% whereas no effect was observed under NT. Under both CT and NT, CH4 oxidation was enhanced after liming application due to decreased Al(3+) toxicity. Based on our results, NT should be promoted as a means to improve soil physical properties and concurrently reduce N2O and CH4 emissions. Raising the soil pH via liming has positive effects on crop yield; here we show that it may also serve to mitigate CH4 emissions and, under CT, abate N2O emissions.
authors.affiliation: Departamento de Química y Tecnología de los Alimentos, E.T.S.I. Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Ciudad Universitaria, 28040 Madrid, Spain. Electronic address: sonia.garcia@upm.es.
authors.forename: Sonia
authors.initials: S
authors.lastname: García-Marco
authors.affiliation: Departamento de Química y Tecnología de los Alimentos, E.T.S.I. Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Ciudad Universitaria, 28040 Madrid, Spain. Electronic address: diego.abalosrodriguez@wur.nl.
authors.forename: Diego
authors.initials: D
authors.lastname: Abalos
authors.affiliation: Departamento de Producción Agraria, E.T.S.I. Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Ciudad Universitaria, 28040 Madrid, Spain. Electronic address: rafael.espejo@upm.es.
authors.forename: Rafael
authors.initials: R
authors.lastname: Espejo
authors.affiliation: Departamento de Química y Tecnología de los Alimentos, E.T.S.I. Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Ciudad Universitaria, 28040 Madrid, Spain. Electronic address: antonio.vallejo@upm.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Vallejo
authors.affiliation: Departamento de Producción Agraria, E.T.S.I. Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Ciudad Universitaria, 28040 Madrid, Spain. Electronic address: i.mariscal@upm.es.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Mariscal-Sancho
keywords: Ca-amendment; Methane; Nitrous oxide; Soil pH; Tillage