Proceedings of the European Conference on Agricultural Engineering AgEng2021

This proceedings book results from the AgEng2021 Agricultural Engineering Conference under auspices of the European Society of Agricultural Engineers, held in an online format based on the University of Évora, Portugal, from 4 to 8 July 2021. This book contains the full papers of a selection of abstracts that were the base for the oral presentations and posters presented at the conference. Presentations were distributed in eleven thematic areas: Artificial Intelligence, data processing and management; Automation, robotics and sensor technology; Circular Economy; Education and Rural development; Energy and bioenergy; Integrated and sustainable Farming systems; New application technologies and mechanisation; Post-harvest technologies; Smart farming / Precision agriculture; Soil, land and water engineering; Sustainable production in Farm buildings

Heat and Mass Transfer in Baled Switchgrass for Storage and Bioconversion Applications

The temperature and moisture content of biomass feedstocks both play a critical role in minimizing storage and transportation costs, achieving effective bioconversion, and developing relevant postharvest quality models. Hence, this study characterizes the heat and mass transfer occurring within baled switchgrass through the development of a mathematical model describing the relevant thermal and physical properties of this specific substrate. This mathematical model accounts for the effect of internal heat generation and temperature-induced free convection within the material in order to improve prediction accuracy. Inclusion of these terms is considered novel in terms of similar biomass models. Two disparate length scales, characterizing both the overall bale structure (global domain) and the individual stems (local domain), are considered with different physical processes occurring on each scale. Material and fluid properties were based on the results of hydraulic conductivity experiments, moisture measurements and thermal analyses that were performed using the constant head method, TDR-based sensors and dual thermal probes, respectively. The unique contributions made by each of these components are also discussed in terms of their particular application within various storage and bioconversion operations. Model validation was performed with rectangular bales of switchgrass (102 x 46 x 36 cm3) stored in an environmental chamber with and without partial insulation to control directional heat transfer. Bale temperatures generally exhibited the same trend as ambient air; although initial periods of microbial growth and heat generation were observed. Moisture content uniformly declined during storage, thereby contributing to minimal heat generation in the latter phases of storage. The mathematical model agreed closely with experimental data for low moisture content levels in terms of describing the temperature and moisture distribution within the material. The inclusion of internal heat generation was found to be necessary for improving the prediction accuracy of the model; particularly in the initial stage of storage. However, the effects of natural convection exhibited minimal contribution to the heat transfer as conduction was observed as the predominate mechanism occurring throughout storage. The results of this study and the newly developed model are expected to enable the maintenance of baled biomass quality during storage and/or high-solids bioconversion

WP3 – Innovation in Agriculture and Forestry Sector for Energetic Sustainability

The papers published in this Special Issue “WP3—Innovation in Agriculture and Forestry Sector for Energetic Sustainability” bring together some of the latest research results in the field of biomass valorization and the process of energy production and climate change and other areas relevant to energetic sustainability [1–20]. Moreover, several works address the very important topic of evaluating the safety aspects for energy plant use [21–24]. Responses to our call generated the following statistics:• Submissions (21);• Publications (15);• Rejections (6);• Article types: research articles (13), reviews (2). Of the submitted papers, 15 have been successfully published as articles. Reviewing and selecting the papers for this Special Issue was very inspiring and rewarding. We also thank the editorial staff and reviewers for their efforts and help during the process. For better comprehension, the contributions to this Special Issue are divided into sections, as follows

Effect of curing conditions and harvesting stage of maturity on Ethiopian onion bulb drying properties

The study was conducted to investigate the impact of curing conditions and harvesting stageson the drying quality of onion bulbs. The onion bulbs (Bombay Red cultivar) were harvested at three harvesting stages (early, optimum, and late maturity) and cured at three different temperatures (30, 40 and 50 oC) and relative humidity (30, 50 and 70%). The results revealed that curing temperature, RH, and maturity stage had significant effects on all measuredattributesexcept total soluble solids

Quantification of methane emissions from cattle farms, using the tracer gas dispersion method

In Denmark, agriculture is the largest source of anthropogenic methane emissions (81%), mainly from cattle (dairy and beef) farms. Whole-farm methane emissions were quantified at nine Danish cattle farms, using the tracer gas dispersion method. Five to six measurement campaigns were carried out at each farm, covering a full year. Of the nine cattle farms, seven were home to dairy cows and two to beef cattle. The farms represented typical breeds, housing and management systems used in Denmark. Whole-farm methane emission rates ranged from 0.7 to 28 kg h−1, with the highest measurements seen at locations with the highest number of animals. Emissions tended to be higher from August to October, due to elevated temperatures and high amounts of stored manure during this period of the year. The average emission factor (EF) for dairy cow farms was 26 \ub1 8.5 g Livestock Unit (LU)−1 h−1, whereas it was 16 \ub1 4.1 LU−1 h−1 for beef cattle farms, i.e. 38% lower for the latter. The use of deep litter house management explained some of the differences found in the EFs for dairy cows. Methane emission rates estimated using IPCC models and national guidelines tended, on average for all farms and measurements, to be underestimated by 35% in comparison with the measured methane emissions, for all models and farms. The results suggest that future improvements to inventory models should focus on enteric methane emissions from beef cattle and manure methane emissions for both dairy cows and beef cattle, especially from deep litter management

Study of ventilation strategies, in agricultural buildings through CFD modeling and experimental analysis.

Environmental control in agricultural and agro-industrial buildings is a very important and topical subject which falls within the domain of precision agriculture and smart food processing. There is a growing interest in the study of systems able to combine active and passive environmental control techniques and in the development of methodologies for modeling and simulating the environmental conditions in the agro-industrial sector. These ones need a process of validation and experimental calibration, but they can investigate specific aspects and variations of the thermo-fluidynamic phenomena involved in the control of environmental parameters. The computational fluid dynamic application (CFD) can give these opportunities and it has been used to study animal comfort in farms, distribution of temperature and humidity in greenhouses, to define structural improvement of greenhouses and to investigate effective ventilation strategies. This thesis is focused on the ventilation aspects in agricultural buildings, with the aim of considering improvement actions to optimize and act on airflow conditions in an experimental greenhouse and in a cellar, where climate control is extremely important. The natural ventilation of a glass greenhouse has been investigated with a particular focus on the effects of internal shading screens on the internal fluid-dynamic and on the crop growing conditions. A deep focus on the characterization of this type of screens has been carried out, with the aim of identifying applicable methodologies for this purpose. Finally, a smart system has been created to be placed in a cellar, for the improvement of the air flows around the barrels, which would thus prevent the molds formation and avoid air stagnation areas. Different configurations have been analyzed to identify the optimal design of the system. In conclusion, CFD approach has allowed to reach conclusions on possible decisions or strategies to improve the ventilation for improving the production and food quality conditions

Agricultural Meteorology and Climatology

Agricultural Meteorology and Climatology is an introductory textbook for meteorology and climatology courses at faculties of agriculture and for agrometeorology and agroclimatology courses at faculties whose curricula include these subjects. Additionally, this book may be a useful source of information for practicing agronomists and all those interested in different aspects of weather and climate impacts on agriculture. In times when scientific knowledge and practical experience increase exponentially, it is not a simple matter to prepare a textbook. Therefore we decided not to constrain Agricultural Meteorology and Climatology by its binding pages. Only a part of it is a conventional textbook. The other part includes numerical examples (easy-to-edit worksheets) and recommended additional reading available on-line in digital form. To keep the reader's attention, the book is divided into three sections: Basics, Applications and Agrometeorological Measurements with Numerical Examples