Animal slurry hygienization for use in industrial horticulture.

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Evaluation of a Tomato Waste Biofilter for the Retention of Gaseous Losses from Pig Slurry Hygienization by pH Modification

Publication . Pereira, José L.S.; Perdigão, Adelaide; Fangueiro, David

The use of pig slurry as organic fertilizer in intensive horticulture could be possible after hygienization to avoid contamination of products. This research aimed to evaluate a mixture of a tomato waste and rice husk as biofilter media to reduce NH3, N2O, CO2, and CH4 losses from a simple and low-cost solution for slurry hygienization by pH modification. The experiment was made in a system of laboratory scale biofilters connected to jars filled with raw slurry as control and three treatment methods: acidified slurry, alkalinized slurry, and neutralized slurry. The gas concentrations were measured for 35 days, and the composition of slurries and biofilters were determined. The results of this study showed that the mixture of biofiltering media, composed of tomato waste and rice husk, has the potential to retain NH3 and greenhouse gases (GHG) from a simple and low-cost solution for slurry hygienization by pH modification. Compared to the treatment raw slurry biofilter, the treatment neutralized slurry biofilter, subjected to a combined treatment by alkalinization/neutralization, retained 19% NH3, 4% CO2, and 83% CH4 losses and had no impact on N2O and global warming potential. Thus, the use of tomato waste biofilter during alkalinization did not increase the loss of NH3 and reduced GHG compared to raw slurry, avoiding the subsequent neutralization of slurry for environmental reasons, and could be used as an organic fertilizer in horticulture. However, using the combined alkalinization/neutralization treatment will improve the fertilizer value of the slurry by adjusting the pH from 9.5 to 7.5

2022Journal article

Open access

Aplicação de chorume em culturas hortícolas. Efeito na produtividade da cultura e na emissão de gases com efeito de estufa

Publication . Coelho, Tiago Miguel Pereira; Mota, Mariana Gomes; Fangueiro, David Paulo

Atualmente, a produção hortícola leva à extração de elevadas quantidades de nutrientes do solo e para combater a falta desses nutrientes, os agricultores aplicam fertilizantes sintéticos que têm um custo elevado. Assim, a utilização de chorume como fonte de nutrientes na horticultura pode ser vantajosa, promovendo o aproveitamento deste efluente pecuário. No entanto, por vezes, o chorume animal pode apresentar microrganismos patogénicos acima dos valores legais, podendo levar à contaminação dos alimentos frescos. Assim, o principal objetivo deste trabalho é verificar o efeito da alteração do pH do chorume animal na sua higienização e na disponibilização de nutrientes por parte do chorume em duas culturas hortícolas - batata e tomate. Também foi avaliado o impacto da higienização do chorume animal na emissão de GEE após aplicação ao solo dos chorumes tratados. Neste trabalho, foram aplicadas seis estratégias diferentes nas culturas: a não aplicação de fertilizante (CT), a aplicação de fertilizante sintético (MN), a aplicação de chorume animal bruto (RA) e a aplicação de chorume animal higienizado através do processo de acidificação (AC), alcalinização (AL) e alcalinização seguida da neutralização (NE). No final deste trabalho, concluiu-se que o chorume animal aumenta a disponibilidade de nutrientes no solo e que a higienização do chorume por alteração do pH foi eficaz. A estratégia RA foi a que obteve os melhores resultados de produtividade para as duas culturas, com 35,61 t ha-1 para a cultura do tomate. Em relação às estratégias em que se utilizou chorume animal higienizado, é importante destacar que a estratégia NE apresentou produtividades elevadas e obteve os melhores resultados na relação entre a emissão dos GEE e a produtividade (517,18 g CO2 eq t-1). A estratégia AC apresentou o menor valor de emissão de GEE (1019,85 mg CO2 eq m-2).

2023-06-15Master thesis

Open access

Impact of sandy soil amendment with dairy slurry treated through pH adjustment on nutrient and coliform leaching

Publication . Rodrigues, Joana; Fragoso, Rita; Brito, Luisa; Fangueiro, David

Livestock farming produces high volumes of animal slurry that can be sanitized using low-cost treatments by pH adjustment, reducing pathogen contamination, and promoting slurry valorization as a safe fertilizer. This work aims to evaluate the impact of sandy soil amendment with dairy slurry treated by pH adjustment on the potential release of nutrients and coliforms into groundwater. A laboratory soil column leaching experiment was conducted and the surface application of six treatments was tested: raw dairy slurry, dairy slurry acidified with H2SO4 , dairy slurry alkalinized with KOH, alkalinized/neutralized dairy slurry, mineral fertilizer, and a control. The fertilizer application rate was 0.08 g N kg−1 dry soil. Leachates were analyzed for pH, electrical conductivity, N-NH4 + and N-NO3 −, macro- and micronutrients, and fecal coliforms. Results showed that amendment with dairy slurry led to significantly lower nitrate leaching potential than mineral fertilizer (maximum 16.1 vs. 50.4%). The use of hygienized slurry by alkalinization decreased the potential leaching of coliforms relative to raw slurry. However, incomplete sanitization by acidification strongly promoted coliform leaching and the risk of groundwater contamination. It can be concluded that the use of alkalinized dairy slurry is a safer solution than raw slurry with regard to the risk of groundwater pollution.

2023Journal article

Open access