Effect of fertilising with pig slurry and chicken manure on GHG emissions from Mediterranean paddies

Abstract

Soil fertilisation affects greenhouse gas emissions. The objective of this study was to compare the effect of different fertilisation strategies on N2O, CH4 emissions and on ecosystem respiration (CO2 emissions), during different periods of rice cultivation (rice crop, postharvest period, and seedling) under Mediterranean climate. Emissions were quantified weekly by the photoacoustic technique at two sites. At Site 1 (2011 and 2012), background treatments were 2 doses of chicken manure (CM): 90 and 170kgNH4(+)-Nha(-1) (CM-90, CM-170), urea (U, 150kgNha(-1)) and no-N (control). Fifty kilogram N ha(-1) ammonium sulphate (AS) were topdress applied to all of them. At Site 2 (2012), background treatments were 2 doses of pig slurry (PS): 91 and 152kgNH4(+)-Nha(-1) (PS-91, PS-152) and ammonium sulphate (AS) at 120kgNH4(+)-Nha(-1) and no-N (control). Sixty kilogram NH4(+)-Nha(-1) as AS were topdress applied to AS and PS-91. During seedling, global warming potential (GWP) was ~3.5-17% of that of the whole rice crop for the CM treatments. The postharvest period was a net sink for CH4, and CO2 emissions only increased for the CM-170 treatment (up to 2MgCO2ha(-1)). The GWP of the entire rice crop reached 17Mg CO2-eqha(-1) for U, and was 14 for CM-170, and 37 for CM-90. The application of PS at agronomic doses (~170kgNha(-1)) allowed high yields (~7.4Mgha(-1)), the control of GWP (~6.5MgCO2-eqha(-1)), and a 13% reduction in greenhouse gas intensity (GHGI) to 0.89kgCO2-eqkg(-1) when compared to AS (1.02kgCO2-eqkg(-1)).

Emissão de CO2 do solo pela aplicação de fertilizantes orgânicos e minerais em ambiente controlado

“…A adição de fertilizantes orgânicos é considerada fonte de energia para os microrganismos do solo (SÁ et al, 2014 O aproveitamento de compostos orgânicos de fácil decomposição como substrato para o crescimento microbiano no solo é responsável por boa parte das emissões de CO 2 na fase inicial após a aplicação, considerando que estas emissões provêm do material orgânico aplicado, sendo maior nos primeiros 15 dias, com posterior redução, segundo Maris et al (2016).…”

“…Houve um pico de emissão diária no 4º dia de coleta, o que pode ser resultado do estímulo provocado pela adição de água ao solo. Maris et al (2016) também observaram estímulo à população microbiana pela variação nos teores de água no solo. A adição de palha representa aporte de energia e nutrientes, o que estimula a população microbiana e aumenta sua atividade metabólica, ocasionando maior emissão de CO 2 .…”

“…A emissão acumulada de CO 2 mostrou interação dos fatores tipo de fertilizantes e palha, mas não houve efeito relacionado ao modo de aplicação dos fertilizantes (Figura 3). Maris et al (2016) verificaram que a injeção de fertilizantes orgânicos até 10cm não é suficiente para mitigar as emissões de CO 2 . Uma possível explicação é proposta por Giacomini et al (2008), que atribuem a semelhança nas emissões de CO 2 à baixa relação C/N da palha.…”

Greenhouse Gas Emissions as Affected by Fertilization Type (Pig Slurry vs. Mineral) and Soil Management in Mediterranean Rice Systems

“…Studies focusing on the influence of organic fertilizers on GHG emissions under flooded rice systems have been carried out in different regions for evaluating products such as straw [6,17,18], green manure [19,20], pig manure [21], pig slurry and chicken manure [22], and anaerobically digested pig slurry (ADPS) [23]. The most consistent result found in the literature is that the incorporation of crop residues increases methane emissions due to the additional C input [6,17,24].…”

“…Huang et al [29] found significant increases in CH 4 emissions by applying ADPS. Under Mediterranean rice conditions, only Maris et al [22] studied the application of PS to flooded rice, and their results showed no significant differences in GHG emissions and GWP for PS fertilization compared to ammonium fertilization. Thus, more studies focusing on the substitution of mineral fertilizers with organic fertilizers to evaluate the effect on GHG emissions are needed in the framework of a more sustainable agriculture.…”