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Recycling organic wastes to agricultural land as a way to improve its quality: A field study to evaluate benefits and risks

Publication . Alvarenga, P.; Palma, Patrícia; Mourinha, C.; Farto, M.; Dores, J.; Patanita, M.; Cunha-Queda, C.; Natal-da-Luz, T.; Renaud, M.; Sousa, J. P.

A field study was established to assess the effects of a sewage sludge (SS), a mixed municipal solid waste compost (MMSWC) and a compost produced from agricultural wastes (AWC), in a Vertisol, using Lolium multiflorum L The amendments were applied for two consecutive years: 6, 12 and 24 t dry matter ha(-1) for SS, and the amendment doses for MMSWC and AWC were calculated to deliver the same amount of organic matter (OM) per unit area. The amendments had significant beneficial effects on some soil properties (e.g. soil OM, N-Kjeldahl, extractable P and K), and on plant productivity parameters (e.g. biomass yield, chlorophyll, foliar area). For instance, soil OM increased from 0.78% to 1.71, 2.48 and 2.51%, after two consecutive years of application of 24 t dry matter ha(-1) of SS, MMSWC and AWC, respectively, while the plant biomass obtained increased from 7.75 t ha(-1) to 152.41, 78.14 and 29.26 t ha(-1), for the same amendments. On the plant, effects were more pronounced for SS than for both compost applications, a consequence of its higher capacity to provide N to the plant in a readily available form. However, after two years of application, the effects on foil properties were more noticeable for both composts, as their OM is more-resistant to mineralization, which endures their beneficial effects on soil. Cadmium, Cr, Ni and Pb pseudo-total concentrations, were not affected significantly by the application of the organic wastes to soil, in all tested doses, neither their extractability by 0.01 M CaCl2. On the contrary, Cu and Zn pseudo-total concentrations increased significantly in the second year of the experiment, following the application of the higher rate of MMSWC and AWC, although their extractability remained very low (<0.5% of their pseudo-total fraction). Trace elements concentrations in the aboveground plant material were lower than their maximum tolerable levels for cattle, used as an indicator of risk of their entry into the human food chain. Despite these results, it is interesting to note that the SS promoted a significant increase in the foliar concentrations of Cu, Ni and Zn that did not happen in composts application, which can be explained by the reduction of the soil pH, as a consequence of SS degradation in soil. Concluding, if this type of organic wastes were to be used in a single application, the rate could be as high as 12 or even 24 t ha(-1), however, if they are to be applied in an annual basis, the application rates should be lowered to assure their safe application (e.g. to 6 t ha(-1)). Moreover, it is advisable to use more stable and mature organic wastes, which have longer lasting positive effects on soil characteristics. (C) 2017 Elsevier Ltd. All rights reserved.

2017-03Journal article

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Application of unsteady-state heat transfer equations to thermal process of morcela de arroz from Monchique region, a portuguese traditional blood sausage

Publication . Pereira, Jorge; Ferreira-Dias, S.; Dionísio, Lídia; Patarata, L.; Matos, T. J. S.

Morcela de Arroz (MA) is a popular cooked blood and rice sausage produced following empirical procedures in the Monchique region, south of Portugal. Presenting high pH (about 6.5) and water activity (around 0.97), it is commercialized without preservatives, unpacked and with restricted commercialization period (1 week at 0C-5C). The aim of this study was (i) to assess the adequacy of unsteady-state heat transfer equations (USHTE) using Heisler charts to predict temperature in the centre of the product and the time needed to attain the temperature needed for cooking and (ii) to determine if the thermal treatment traditionally applied complies with the recommendations for refrigerated processed foods of extended durability (REPFEDs). A very good fit of USHTE to the experimental time/temperature data was observed. MA thermal process complies with the REPFEDs recommendations. Bacillus cereus and Clostridium perfringens were not detected in any of the tested samples.

2017-04Journal article

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Effects of the European Union agricultural and environmental policies in the sustainability of most common Mediterranean soils

Publication . Rato Nunes, Jose Manuel; Bonito, Antonio; Loures, Luis; Gama, Jose; Lopez-Pineiro, Antonio; Pena, David; Albarran, Angel

Agro-environmental measures promoted by the European Union focus mainly on environmental protection by maintaining sustainable levels of productivity that are adequate to the agro-ecological conditions of each region on different Member States. Among these European Union promoted measures the one known as Extensive Forage Systems is particularly relevant for the Mediterranean Region. In order to analyze the impact of this measure and to verify if the high expenditure of communitarian funds, with its implementation in Mediterranean soils, is aligned with the predicted benefits, a seven-year study in a southern Portugal region was conducted. In this regard, several soil chemical parameters such as organic matter, pH, electrical conductivity, available phosphorus, "available" potassium and heavy metal levels (Cd, Cr, Cu, Zn, Mn, Pb and Ni), were assessed, in 1329 different plots in order to represent some of the existing diversity of the Mediterranean environment, identified by the Portuguese Parcel Identification System, and considering the possibility to evaluate the evolution of these parameters on the main soil types of the region. The obtained results enabled us to verify that the application of the agro-environmental measure Extensive Forage Systems did not lead, during the 7 years of the study, to any significant change in terms of organic matter, soil pH and/or heavy metals content. Still it contributed for a small growth on "available" phosphorus and potassium levels and to a significant increase on Soil electrical conductivity (EC). As a final conclusion we can refer that the application of the agro-environmental measure Extensive Forage Systems, in soil, clime and cultural conditions prevailing in this study (Typical Mediterranean conditions from the South of Europe), did not reach its main objective, which was to increase the organic matter content in soils.

2017-08Journal article

Open access