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Closing Knowledge Gaps on Slurry Application in Conservation Agriculture with Special Emphasis on Stubble-covered Soil
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Orientador(es)
Resumo(s)
Animal slurry, as a fertilizer, delivers nutrients, organic carbon and beneficial microorganisms, improving crop production and soil health. In replacement of synthetic fertilizers, slurry reduces costs as well as the carbon footprint of the farm. However, slurries can also be a source of ammonia (NH3), the main N loss pathway after application to the soil, and greenhouse gas (GHG) emissions to the atmosphere with negative environmental impacts as well as threatening animal and human health. The most used NH3 emission reduction measure is the incorporation of slurry into the soil, but this practice is incompatible with conservation agriculture (CA), a cropping system based on the maintenance of the soil cover and its minimum disturbance. Also, in many countries, there is no specific regulation for slurry application under CA. In the present thesis, some suitable strategies for slurry application to stubble-covered soil, with the potential to reduce nitrogen losses as well as the costs of transport and application were assessed, through their effects on the crop yield and nutrient recovery, NH3 and GHG emissions. Irrigation after slurry application and the placement of the slurry under the stubble decreased NH3 emissions, without significant differences from slurry injection and synthetic fertilization relative to crop yield, nutrient recovery efficiency and GHG emissions. Application 8 days after sowing, behaved similarly to the application on the sowing day, giving the farmer an enlargement in the fertilization window. Slurry acidification, applied alone or mixed with urea, was the most efficient solution, enabling the synthetic fertilizer replacement, without the need for incorporation. Thus, this thesis provided some solutions to promote slurry fertilization in CA, helping to overcome the main obstacles faced by the stakeholders. Furthermore, the results obtained can support future regulations concerning the slurry application, addressed to conservation farmers.
Descrição
Doutoramento em Engenharia Agronómica / Instituto Superior de Agronomia. Universidade de Lisboa
Palavras-chave
no-till crop residues NH3 N2O GHG
Contexto Educativo
Citação
Silva, A.A.S. - Closing Knowledge Gaps on Slurry Application in Conservation Agriculture with Special Emphasis on Stubble-covered Soil. Lisboa: ISA, 2022, 167 p.