No-tillage reduces long-term yield-scaled soil nitrous oxide emissions in rainfed Mediterranean agroecosystems: A field and modelling approach

• Published in: Agriculture, ecosystems & environment ecosystems & environment, 2018-07, Vol.262, p.36-47
• Main Authors: Plaza-Bonilla, Daniel, Álvaro-Fuentes, Jorge, Bareche, Javier, Pareja-Sánchez, Evangelina, Justes, Éric, Cantero-Martínez, Carlos
• Format: Article
• Language: English
• Subjects: Adequacy; Agricultural ecosystems; Agricultural management; Agricultural practices; Agricultural production; Agronomy; Barley; Computer simulation; Crop yield; Crops; Data processing; Emission factor; Emission measurements; Emissions; Environmental Sciences; Humanities and Social Sciences; Hydrologic data; Life Sciences; Mathematical models; Mediterranean; Moisture content; N fertilization; Nitric oxide; Nitrous oxide; Precipitation; Productivity; Rain; Rainfall; Rainfed cropping systems; Soil dynamics; Soil management; Soil water; Soils; STICS model; Tillage
• ISSN: 0167-8809; 1873-2305; 0167-8809
• DOI: 10.1016/j.agee.2018.04.007

•STICS was used to simulate 18-yr soil N2O emissions and emission factor (EF).•Yield-scaled N2O emissions (YSNE) were calculated with observed yields.•Yield under no-till (NT) with N exceeded conventional tillage (CT) in 11 years.•Mean EF was 0.55% and only surpassed 1% (IPCC default value) in 3 years.•The 18-yr mean YSNE were 2.8 to 3.3 times lower under NT, compared to CT. There is a strong need to identify agricultural management practices that maintain agronomic productivity while diminishing soil N2O emissions. The yield-scaled N2O emissions (YSNE) indicator can help to evaluate the adequacy of a given agricultural practice under both aspects. Long-term (18-yr) soil water and mineral N dynamics, crop biomass and yields, and 2011–2012 soil N2O emissions and ancillary variables were measured on barley (Hordeum vulgare L.) production in a tillage (conventional tillage, CT; no-tillage, NT) and N rate (0, 60 and 120 kg N ha−1) combination under rainfed Mediterranean conditions (NE Spain). Once evaluated, the STICS soil-crop model was used to simulate the 18-yr soil N2O emissions of each tillage system under increasing N rates (0, 30, 60, 90 and 120 kg N ha−1) in order to identify optimum management to reduce YSNE, being initialized with observed data. Cropping season precipitation was highly variable during the experiment, being a key regulating mechanism for crop yields and simulated soil N2O emissions. Crop yield under NT with N outperformed CT in 11 years. STICS performed reasonably well when simulating cumulative N2O emissions and ancillary variables with model efficiencies greater than 0.5. The 18-yr average simulated cumulative N2O emissions were 0.50, 0.82 and 1.09 kg N2O-N ha−1 yr−1 for CT-0, CT-60 and CT-120, respectively, and they were 0.53, 0.92 and 1.19 kg N2O-N ha−1 yr−1 for their counterparts under NT. These averages mask a large variability between years, according to precipitation. The 18-yr mean yield-scaled N2O emissions were 2.8–3.3 times lower under NT, compared to the corresponding CT treatments. Under CT, N application would increase YSNE in most years while YSNE would be more resilient to the application of increasing N rates under NT. Our work demonstrates that in rainfed Mediterranean systems NT is a win-win strategy for the equilibrium between agricultural productivity and low soil N2O emissions.