Management of pig manure to mitigate NO and yield-scaled N2O emissions in an irrigated Mediterranean crop

Abstract

Substitution of conventional mineral fertilizers with organic sources can avoid the environmental problems associated with high concentrations of intensive livestock production in some Mediterranean areas. Some management practices, such as the use of nitrification inhibitors or more efficient irrigation techniques (e.g., drip irrigation), have been suggested as effective alternatives to mitigate nitrous oxide (N 2 O) and nitric oxide (NO) emissions released from soils amended with synthetic and organic fertilizers. In this experiment, we aimed to assess the effect of different organic amendments derived from pig manure (control without N fertilization (C); liquid fraction of pig slurry (LFPS); pig urine with the nitrification inhibitor 3,4 dimethylpyrazolephosphate (DMPP) (LFPSI); compost from the solid phase of pig slurry (COM)) compared to urea (U) and two different irrigation systems (the widespread sprinkler and alternative drip irrigation systems) on greenhouse gas (N 2 O, methane, CH 4 , and carbon dioxide, CO 2) and NO emissions in a maize (Zea mays L.) crop. The effect of these treatments on crop yields and yieldscaled N 2 O emissions were also evaluated. The use of DMPP with LFPS was an effective practice to reduce N 2 O and NO losses (40 and 32% mitigation, respectively, compared to LFPS alone), and was also associated with the highest rates of CH 4 oxidation. Drip irrigation significantly reduced the global warming potential (in spite of a lower CH 4 sink) but increased the NO losses by 58%, as opposed to sprinkler irrigation. The higher biomass production and similar grain yields observed with drip irrigation resulted in lower yieldscaled N 2 O emissions in this treatment than in sprinkler irrigation. The use of organic fertilizers penalized grain yields compared to U (16-33%), although the differences were not significant in the case of LFPSI. Consequently, LFPSI in drip irrigation was (together with U applied by drip-fertigation) the treatment that led to the lowest yield-scaled N 2 O emissions. The use of organic N sources in irrigated maize is an environmentally advisable strategy in Mediterranean cropping systems, but an optimum balance between N oxides and greenhouse gas losses, N efficiency and crop yields requires the use of nitrification inhibitors (e.g., DMPP) with liquid organic sources. 2016 Elsevier B.V. All rights reserved.

Synthetic inhibitors, a way towards the nitrogen-neutrality in mediterranean agroecosystems

“…This study showed that the use of DMPP could be considered an effective strategy to reduce direct N2O emissions from PS (reduction of c. 70% of N2O emissions) mainly because, as reported by Chadwick et al (2011), under the study conditions, an important fraction of N2O emitted after DMPP application was produced through nitrification. Our results also confirm those of Guardia et al (2017b) who observed a 49% inhibitory effect of DMPP on N2O emissions when 120 kg N ha -1 of liquid PS fraction was applied to a maize crop. Additionally, DMPSA mitigated 40% of total N2O fluxes within the first three weeks after top-dressing fertilizer application, with N2O losses in DMPSA plots similar to those of the unfertilized treatment (Table 5.2).…”

“…Additionally, DMPSA mitigated 40% of total N2O fluxes within the first three weeks after top-dressing fertilizer application, with N2O losses in DMPSA plots similar to those of the unfertilized treatment (Table 5.2). Guardia et al (2017b) found a significant inhibitory effect of 57% when applying CAN and DMPSA (180 kg N ha -1 ), also in a maize crop in a clay soil, suggesting that nitrification was the dominant N2O production process at the peaking time. The nitrification inhibitory effect of DMPSA is not well known yet, but probably its effect is based on the presence of dimethylpyrazole (DMP), which is released through the degradation of succinic acid in soil.…”

“…split application of fertilizers), using water-saving irrigation strategies (e.g. drip irrigation) to prevent N2O formation through denitrification in water-saturated soils (Guardia et al, 2017b) or applying nitrification inhibitors (NIs) (Sanz-Cobena et al, 2017).…”

Water regime affects soil N2O emission and tomato yield grown under different types of fertilisers

“…In particular, water supply can also increase N2O emissions favoring conditions for nitrification and denitrification (Maris et al, 2015), while a rational management of irrigation can enhance crop yield and mitigate the impact of cropping systems on environment and global climate by favoring Carbon sequestration and reducing GHGs emission. Most of the studies on the effects of NIs and organic and organomineral fertilisers on crop production and N2O emission has been carried out under optimal irrigation conditions (Vitale et al, 2013;Guardia et al, 2016;Huérfano et al, 2016;Vitale et al, 2017), while little information is available for open field crops under reduced water supply (Albalos et al, 2016).…”

“…In this frame, several different approaches have been proposed in terms of appropriate management of irrigation (Vallejo et al, 2014;Meijjde et al, 2016;Wolff et al, 2016) as well as of fertilisation, such as the use of fertilisers added with nitrification inhibitors (NIs) (Vitale et al, 2013;Abalos et al, 2016;Hube et al, 2016;Huérfano et al, 2016;Vitale et al, 2017) and organo or organomineral fertilisers (Ball et al, 2004;Guardia et al, 2016;Vitale et al, 2017). The latter release nitrogen (N) more gradually over the course of season, compared to conventional mineral fertilisers, thus improving synchrony between soil N availability and crop N demand and potentially increasing overall efficiency of fertiliser use.…”