Substitution of conventional mineral fertilizers with organic sources can avoid the environmental problems associated with high concentrations of intensive livestock production in some Mediterranean areas. Some management practices, such as the use of nitrification inhibitors or more efficient irrigation techniques (e.g., drip irrigation), have been suggested as effective alternatives to mitigate nitrous oxide (N 2 O) and nitric oxide (NO) emissions released from soils amended with synthetic and organic fertilizers. In this experiment, we aimed to assess the effect of different organic amendments derived from pig manure (control without N fertilization (C); liquid fraction of pig slurry (LFPS); pig urine with the nitrification inhibitor 3,4 dimethylpyrazolephosphate (DMPP) (LFPSI); compost from the solid phase of pig slurry (COM)) compared to urea (U) and two different irrigation systems (the widespread sprinkler and alternative drip irrigation systems) on greenhouse gas (N 2 O, methane, CH 4 , and carbon dioxide, CO 2) and NO emissions in a maize (Zea mays L.) crop. The effect of these treatments on crop yields and yieldscaled N 2 O emissions were also evaluated. The use of DMPP with LFPS was an effective practice to reduce N 2 O and NO losses (40 and 32% mitigation, respectively, compared to LFPS alone), and was also associated with the highest rates of CH 4 oxidation. Drip irrigation significantly reduced the global warming potential (in spite of a lower CH 4 sink) but increased the NO losses by 58%, as opposed to sprinkler irrigation. The higher biomass production and similar grain yields observed with drip irrigation resulted in lower yieldscaled N 2 O emissions in this treatment than in sprinkler irrigation. The use of organic fertilizers penalized grain yields compared to U (16-33%), although the differences were not significant in the case of LFPSI. Consequently, LFPSI in drip irrigation was (together with U applied by drip-fertigation) the treatment that led to the lowest yield-scaled N 2 O emissions. The use of organic N sources in irrigated maize is an environmentally advisable strategy in Mediterranean cropping systems, but an optimum balance between N oxides and greenhouse gas losses, N efficiency and crop yields requires the use of nitrification inhibitors (e.g., DMPP) with liquid organic sources. 2016 Elsevier B.V. All rights reserved.
Abstract:This work aimed to evaluate the biogas production potential of swine manure (SM)
O trabalho objetivou avaliar o efeito da codigestão de água residuária de laticínio com dejetos bovinos em biodigestores do tipo batelada sobre a produção de biogás. Avaliou-se o efeito da inclusão de água residuária de laticínio (ARL): 0% de ARL, 50% de ARL, 77,5 % de ARL, 100% de ARL com 8% de sólidos totais (ST) e tratamento com 100% de ARL com 1,8% de sólidos totais. Para análise dos dados considerou-se um delineamento inteiramente casualizado, utilizando-se o programa SAS® com nível de significância de 5%. Para a variável analisada, produção total de biogás, houve resposta da substituição da agua potável pela agua residuária de laticínio com 8% de ST no volume de biogás produzido, apresentando maiores médias quando comparado ao tratamento com 1,8 de ST. Para as variáveis de potenciais de produção exceto pela produção por kg de sólidos voláteis reduzidos houve diferença significativa para o tratamento com 50% de ARL e ST 8%. O aproveitamento da água residuária para compor substrato em codigestão com dejetos bovinos leiteiros apresentou condições favoráveis de produção de biogás.
The objective of this study was to evaluate the effects of the addition of sugarcane juice on the population dynamics of Escherichia coli and the presence of Shiga-toxigenic E. coli (STEC) during the anaerobic codigestion of dairy cattle manure. For the overall analyses at the end of a hydraulic retention time of 90 days, ten two-liter batch-type biodigesters were divided into two treatment groups: biodigester containing manure and water (MW) and the biodigester containing manure, water and sugarcane juice (MSC). For monitoring the population dynamics and presence of microorganisms, pH, and volatile acidity, tests were carried out every ten days, on 36 smaller-scale batch biodigesters made of one-liter plastic bottles (18 for each treatment). The reductions in E. coli population over time were significant in the MW (60 days) and MSC (20 days) biodigesters. Inactivation of STEC occurred in a shorter period (40 days in MW and <10 days in MSC). Significant differences were obtained between the two treatments, with the pH values being lower, the concentrations of volatile acids (VA) being higher, and the inactivation of E. coli and STEC being faster in the biodigester with sugarcane juice added. The amount of sugarcane juice applied (7%) suggests its suitability for the sanitization of dairy cattle manure for use as a biofertilizer, given the high reduction in the E. coli population and inactivation of STEC.RESUMO: O estudo teve como objetivo avaliar o efeito da adição de caldo de cana-de-açúcar sobre a dinâmica da população de Escherichia coli e presença de E. coli shigatogixênicas (STEC) no processo de codigestão anaeróbia de dejetos de bovinos leiteiros. Foram utilizados dez biodigestores bateladas divididos em dois tratamentos, dejeto sem caldo de cana-de-açúcar (DSC) e dejeto com caldo (DCC), com tempo de retenção hidráulica (TRH) de 90 dias. Para o monitoramento periódico da dinâmica da população E. coli e presença de E. coli shigatoxigenicas, do pH e da acidez volátil, realizados a cada dez dias, foram abastecidos mais 36 biodigestores bateladas, construídos de garrafas de material plástico de um litro, sendo 18 unidades para cada tratamento. A redução das populações de E. coli no decorrer do tempo foi significativa no DSC (60 dias) e no DCC (20 dias). A inativação de E. coli shigatoxigênicas ocorreu em um período mais curto, 40 dias no DSC e menos de 10 dias no DCC. Foram obtidas diferenças significativas entre os tratamentos para os valores de pH, que foram menores, e as concentrações de ácidos voláteis, que foram maiores, com adição de caldo e contribuíram para a inativação mais rápida da E. coli e STEC. A dose de caldo de cana-de-açúcar utilizada (7%) sugere a adequada sanitização do dejeto bovino leiteiro, tendo em vista a alta redução na população de E. coli e a inativação de STEC. Palavras-chave: biodigestão anaróbia, micro-organismos patogênicos, sustentabilidade ambiental, tratamento de dejetos.
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