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Tracing organic carbon cycling in agricultural soils of different catch crop management systems by 13C pulse labelling

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Resumo:The loss of nutrients from agricultural soils leads to environmental problems and the infraction of environmental laws. Catch crops are a type of cover crop that are used in rotations as a way of avoiding soil nutrients from leaching. These crops may enhance other properties of the soil regarding quality and biological activity. The aim of this thesis is to explore these benefits by comparing fallow soil, to that of a single-species catch crop (Mustard) and the soils of two multi-species catch crops (Mix4, containing four species, and a commercial mix TerraLife, containing thirteen), on the same agricultural soil in Lower Saxony, Germany. A 13C pulse labelling experiment was conducted to trace C through the atmosphere-plant-soil microbiome interphase. Net Ecosystem Production (NEP) of the different catch crops was calculated by monitoring gas fluxes. Soil microbial phospholipid fatty acids (PLFAs) were extracted, as a means of quantifying the relative amount of the microbial community and identifying relative differences among the soil samples. NEP was significantly higher in the TerraLife soil when compared to the fallow soil and the Mustard suggesting that the higher the plant diversity, the higher the C fixation. The TerraLife soil presented higher extracted PLFA values, being significantly higher than the fallow soil at 0-10 cm for total PLFAs and fungal PLFAs, suggesting that higher plant diversity induces higher microbial biomass. And the soil microbial community structure seemed to present two different trends, with a higher Fungi/Bacteria ratio in the TerraLife and Mix4 soils and similar values for the Mustard and fallow soils. The results suggest that multi-species catch crops provide higher C fixation rates and promote soil microbiota when compared to single-species crops or fallow soil. Further research that focuses on functional traits between individual catch crops and their microbiome is still needed in order to contrast and better interpret the information currently available on the subject.
Autores principais:Batalla, Juan Daniel Kennedy
Assunto:Microbiota do solo 13C PLFA NEP Sustentabilidade agrícola Teses de mestrado - 2018
Ano:2018
País:Portugal
Tipo de documento:dissertação de mestrado
Tipo de acesso:acesso aberto
Instituição associada:Universidade de Lisboa
Idioma:inglês
Origem:Repositório da Universidade de Lisboa

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