Comparison of N losses (NO −3, N 2O, NO) from surface applied, injected or amended (DCD) pig slurry of an irrigated soil in a Mediterranean climate

Abstract

Nitrous oxide (N 2 O), nitric oxide (NO), denitrification losses and NO À 3 leaching from an irrigated sward were quantified under Mediterranean conditions. The effect of injected pig slurry (IPS) with and without the nitrification inhibitor dicyandiamide (DCD) was evaluated and also compared with that of a surface pig slurry application (SPS) and a control treatment (Control) without fertiliser. After application, fluxes of NO and N 2 O peaked from SPS (3.06 mg NO-N m )2 d )1 and 108 mg N 2 O-N m )2 d )1 ) and IPS (3.50 mg NO-N m )2 d )1 and 105 mg N 2 O-N m )2 d )1 ). However, when irrigation was applied, N 2 O and NO emissions declined. The total N 2 O and denitrification losses were slightly large from IPS than from SPS, although the differences were not significant (P < 0.05). Emission of NO was not affected by the method of pig slurry application. DCD inhibited nitrification during the first 20-30 days and reduced N 2 O and NO emissions from pig slurry by at least 46% and 37%, respectively. Considering the 215 days following pig slurry application, the emission factor of N 2 O based on N fertiliser was 1.60% (SPS), 2.95% (IPS), and 0.50% (IPS + DCD). The emission factor for NO was 0.14% (SPS), 0.12% (IPS), and 0.02% (IPS + DCD). Environmental conditions of the crop favoured the denitrification process as the most important source of N 2 O during the experimental period. The differences in the denitrification rate between treatments could be explained by the pattern of water soluble carbon (WSC), that was the highest value in injected pig slurry (with and without DCD). Due to low drainage (5% of water applied), leaching losses of NO À 3 were lower than those of denitrification from the upper soil layer (0-10 cm) in all treatments and especially with IPS + DCD, where the nitrification inhibitor was very efficient in reducing leaching losses.

Impact of dicyandiamide on emissions of nitrous oxide, nitric oxide and ammonia from agricultural field in the North China Plain

“…The reduction effect of DCD on NO emission may depend on the application rate of DCD, soil character (texture, pH, moisture and temperature), the available NH 4 + concentration, and so on. Under the same application rate of DCD (10%) as ours, Akiyama et al (2015) reported that DCD could reduce 75% of NO emissions in an acid Andosol soil (a volcanic ash soil), whereas Vallejo et al (2005) found that the NO emission was only reduced by 37% with a lower application rate of DCD (5%) into a loam texture soil (pH = 8.1). Because NO emission from field soil is mainly ascribed to nitrification (Zhang et al, 2011;Cui et al, 2012) and negatively correlates to soil moisture (as evidenced by the later NO emission peak from the NP treatment in comparison with N 2 O emission), both the suppression of nitrification by DCD application and the extremely high soil moisture after the fertilization and irrigation in this study favored reduction of NO emission, resulting in the ND treatment having the largest reduction loss rate of NO emission.…”

“…Compared with the NO flux from the NP treatment, the almost identical negative NO fluxes from the CK and ND treatments indicated that the application of DCD could reduce NO loss from the fertilizer application nearly 100%, which was much greater than the percentages (37%-78%) reported in the literature (Meijide et al, 2007;Vallejo et al, 2005;Akiyama et al, 2015). The reduction effect of DCD on NO emission may depend on the application rate of DCD, soil character (texture, pH, moisture and temperature), the available NH 4 + concentration, and so on.…”

“…It has been well in the nitrification process (Kelliher et al, 2008). DCD has been shown to effectively reduce N 2 O emissions from pasture (Zaman et al, 2008;Cameron et al, 2014;Robinson et al, 2014), grassland (Di and Cameron, 2003;Di et al, 2010), paddy fields (Kumar et al, 2000;Li et al, 2009) and upland soil (Majumdar et al, 2002;Vallejo et al, 2005;Meijide et al, 2007). Both NO and N 2 O are important byproducts of nitrification; however, only few studies (Vallejo et al, 2005;Meijide et al, 2007) have investigated the reduction effect of DCD for both N 2 O and NO from agricultural fields.…”

Inibidor de nitrificação e aplicação parcelada de dejetos de suínos nas culturas do milho e trigo

“…No trabalho de Moir et al (2007), a aplicação de DCD (10 kg ha -1 em maio e 10 kg ha -1 em agosto) em uma pastagem com adição de doses elevadas de urina de vacas resultou em aumento médio de 21 % na produção da pastagem. Quando a DCD foi aplicada como inibidor da nitrificação do N amoniacal de dejetos líquidos de suínos (Vallejo et al, 2005) e de bovinos (Tao et al, 2008), o seu efeito foi avaliado apenas sobre as perdas de NO 3 -, N 2 O, NO e NH 3 .…”

“…A incorporação e a injeção dos dejetos no solo podem reduzir a volatilização de NH 3 em pelo menos 90 % (Webb et al, 2010), embora essas possam aumentar as perdas de N por desnitrificação (Wulf et al, 2002). O uso de inibidores de nitrificação no momento da aplicação dos dejetos pode reduzir as emissões de N 2 O (Vallejo et al, 2005;Damasceno, 2010), que podem ocorrer tanto durante a nitrificação do N amoniacal dos dejetos quanto durante a desnitrificação (Arcara et al, 1999). A redução na taxa de nitrificação até que a planta atinja a fase de maior crescimento aumentará a oportunidade dessa em absorver o NO 3 - (Subbarao et (Zaman et al, 2009;Damasceno, 2010).…”