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Effect of N dose on soil GHG emissions from a drip-fertigated olive (Olea europaea L.) orchard

Vilarrasa-Nogué, M., Teira-Esmatges, M.R., Villar, J.M., Rufat, J.
The Science of the total environment 2019 v.677 pp. 350-361
Olea europaea, crops, deficit irrigation, greenhouse gas emissions, greenhouse gases, irrigation rates, methane, methane production, microirrigation, nitrogen, nitrous oxide, olives, orchards, oxidation, plant cultural practices, profitability, soil water, soil water content, trees, water conservation
Agronomic practices may mitigate greenhouse gas emissions (GHG) from crops. Appropriate nitrogen (N) and irrigation management provide the potential to reduce nitrous oxide (N2O) and methane (CH4) emissions. However, there is little information about the combination of both practices on the GHG emissions from olive orchards. This four-year study was conducted to qualitatively compare the effect of N doses applied through two drip irrigation strategies on N2O and CH4 emissions in a super-intensive (1010 trees ha−1) olive orchard. The design (randomised blocks) was asymmetric: 0, 50 and 100 kg N ha−1 yr−1 were tested with full irrigation (FI; 2013 to 2016), but only 0 and 50 kg N ha−1 yr−1 were tested with regulated deficit irrigation (RDI; 2014 to 2016). The study shows that the soil acted as a main sink of N2O and CH4, regardless of the soil water content. Methane oxidation increased with N dose in the FI strategy (significant in 2013 and 2015). Overall, there was a tendency of yield to increase with the N dose without increasing emissions and without depending of the irrigation strategy. However, these results were not significant. Further confirmation of this tendency is necessary; particularly comparing FI + N100 (most promising treatment in terms of profitability) with the RDI + N100 (not available in this study) water-saving strategy.