Journal of Agricultural Engineering
ISSN / EISSN : 1974-7071 / 2239-6268
Published by: PAGEPress Publications (10.4081)
Total articles ≅ 867
Latest articles in this journal
Journal of Agricultural Engineering, Volume 52; https://doi.org/10.4081/jae.2021.1147
The process of cutting with a blade is largely applied in agricultural equipment and is used to process raw materials with different physical and mechanical properties. Nonetheless, the functional relation between the kinematic parameters of a vibroblade and the crucial power parameters of the vibration processing has not yet been studied in great depth so far. This type of studies is essential to create databases for further investigation and design of novel cutting machinery or technologies to ensure effective processing of vibrocutting. Our objective was to obtain the power characteristics of vibrocutting through laboratory experiments [using the example of vibrocutting of common reed (Phragmites australis)] and define the combination of factors (i.e., vibration amplitude, frequency and the blade feeding speed) at the minimum cutting force. The following relation of the blade feeding speed (V) and vibration speed of the toothed blade (Vt) has been established as optimal kinematic regime: K≅0.004. Tests have indicated that use of toothed blades for vibrocutting of the raw products of plant origin offers a greater advantage over the blades with flat edges. An optimal cutting regime, when energy expenses are at a minimum, was ensured with the following parameters of the vibroblade: vibration amplitude: 14 mm, frequency: 33.32 s–1, the blade feeding speed: 7.5×10–3 m.
Journal of Agricultural Engineering, Volume 52; https://doi.org/10.4081/jae.2021.1209
Light intensity, temperature, and humidity are key factors affecting photosynthesis, respiration, and transpiration. Among these factors, temperature is a crucial parameter to establish an optimal greenhouse climate. Temperature can be controlled by using an appropriate climate screen, which has a considerable impact on crop quantity and quality. The precise measurements of longwave radiative properties of screens are vital to the selection of the most suitable screen for greenhouses so that the desired temperature and a favorable environment can be provided to plants during nighttime. The energy-saving capability of screens can also be calculated by using these properties as inputs in a physical model. Two approaches have been reported so far in the literature for the measurement of these properties, i.e., spectrophotometry and wideband radiometry. In this study, we proposed some modified radiation balance methods for determining the total hemispherical longwave radiative properties of different screens by using wide-band radiometers. The proposed method is applicable to materials having zero porosity, partial opacity, and asymmetric screens with 100% solidity. These materials were not studied previously under natural conditions. The existing and proposed methods were applied and compared, and it was found that the radiometric values obtained from the developed methodology were similar to those previously reported in the literature, whereas the existing method gave unstable results with zero reflectance.
Journal of Agricultural Engineering, Volume 52; https://doi.org/10.4081/jae.2021.1199
A simple test for shelf-life assessment of frozen spinach and parsley is presented. A specific shelf-life test that considers three storage temperatures is proposed to accelerate the rate of quality decay in frozen spinach and parsley. The scope was to provide a reliable and rapid way (one month vs years) to predict shelf-life by using a simple experimental approach and mathematical models based on some physical quality product attributes. Physical properties were evaluated at three storage temperatures: –5°C, –10°C and –26°C, to simulate a possible thermal abuse. Mechanical and thermal indexes were defined measuring maximum compression force (N) and latent heat involved in ice melting (J/g). A zeroorder kinetic model was used to properly fit experimental data and thus to obtain related reaction rates. The determination coefficient indicates that there is a strong linear relation between kinetic parameters at –10°C or –5°C and –26°C. This suggests a reliable procedure for shelf-life estimation, carrying out a test at –10°C or –5°C for one month and extending values to data acquired at – 26°C for the same period of time. The relations obtained from this research have led to a simple practical approach: one day at –10°C could be considered roughly equivalent to 30 days at –26°C. Accordingly, it could be possible to obtain a shelf-life estimation in short time, also considering other similar products.
Journal of Agricultural Engineering, Volume 52; https://doi.org/10.4081/jae.2021.1172
Sprinkler systems are one of the most popular methods of irrigation worldwide. One of their key parameters is the so-called level of uniformity, i.e. every portion of the soil should be irrigated with the same amount of water. Assessing the level of uniformity is crucial for optimal design of sprinkler systems. In this manuscript, a novel experimental benchmark is presented in order to test irrigation sprinklers, assess their performance, and define their acceptable working conditions. Different sprinklers have been tested, their water application depth curves have been determined, and their performance has been evaluated using a combination of metrics. Results show that the majority of sprinklers are characterized by very good performance in terms of operating pressures in the range 2.0-3.0 bar and tend to decrease their efficiency for operating pressures outside of that range.
Journal of Agricultural Engineering, Volume 52; https://doi.org/10.4081/jae.2021.1189
The aim of this paper is the analysis, proposal and application of a structural tensegrity configuration for greenhouses supporting structures suitable for lightweight covering, based on principles of design coherence, material savings and building durability. By means of the FEM software, Sofistik®, a tensegral greenhouse prototype was modelled and designed in accordance with EN 13031-1:2019. In order to calibrate the results of the FEM analysis, experimental load tests and displacement measurements made with a tensegrity reduced scale model on a tensegrity reduced scale model, created at the Department laboratory of the University of Bari, were compared with the results of the calculation analysis. The displacements of the prototype selected nodes were detected by Target tracking Technology in two load configurations and a control transducer was positioned on the central structural node. The comparison among the displacements of the detected nodes with those resulting from the FEM software calculations, for two different load configurations, show average percentage errors of 7.1% and 12.55%. The results of the T test for the different load configuration point out that the two series of values experimentally detected and calculated by the software are not significantly different. Finally, results in terms of the structural steel weight and maximum stress of the tensegral structure were compared with those of commercial structures, both with vaulted roof and duopitched roof, of single span greenhouses having the same covered ground area of the greenhouse prototype. The proposed tensegrity greenhouse prototype showed a 9.6% and 35.2% reduction of the structural steel weight compared to the vaulted roof and to the duo-pitched roof greenhouse respectively.
Journal of Agricultural Engineering, Volume 52; https://doi.org/10.4081/jae.2021.1185
In order to reduce greenhouse gas emissions, low emission or zero-emission technologies have been applied to light and heavyduty vehicles by adopting electric propulsion systems and battery energy storage. Hybrid cable yarders and electrical slack-pulling carriages could represent an opportunity to increase the energy efficiency of forestry operations leading to lower impact timber harvesting and economic savings thanks to reduced fuel consumption. However, given the limited experience with hybrid-electric systems applied to cable yarding operations, these assumptions remain uncertain. This study assessed an uphill cable yarding operation using a hybrid cable yarder and an active slack-pulling electric power carriage over thirty working days. A total of 915 work cycles on four different cable lines were analysed. Longterm monitoring using Can-BUS data and direct field observations were used to evaluate the total energy efficiency, total energy efficiency (%), and fuel consumption per unit of timber extracted (L/m3). The use of the electric-hybrid system with a 700 V supercapacitor to store the recovered energy made it possible to reduce the running time of the engine by about 38% of the total working time. However, only 35% to 41% of the Diesel-based mechanical energy was consumed by the mainline and haulback winches. Indeed, the remaining energy was consumed by the other winches of the cable line system (skyline, strawline winches and carriage recharging or breaking during outhaul) or dissipated by the system (e.g., by the haulback blocks). With reference to all work cycles, the highest net energy consumption occurred during the inhaulunload work element with a maximum of 1.15 kWh, consuming 70% of total net energy consumption to complete a work cycle. In contrast, lower energy consumption was recorded for lateral skid and outhaul, recording a maximum of 23% and 32% of the total net energy consumption, respectively. The estimated recovered energy, on average between the four cable lines, was 2.56 kWh. Therefore, the reduced fuel need was assessed to be approximately 730 L of fuel in the 212.5 PMH15 of observation, for a total emissions reduction of 1907 kg CO2 eq, 2.08 kg CO2 eq for each work cycle.
Journal of Agricultural Engineering, Volume 52; https://doi.org/10.4081/jae.2021.1205
Energy consumption in greenhouse heating could reach up to 90% of the total energy requirement depending on the type of greenhouse, environmental control equipment and location of the greenhouse. The use of climate conditioning technologies that exploit renewable energy and the application of passive systems to improve the energy efficiency and the sustainability of the greenhouse sector are recommended. During winter 2020-2021, an experimental test was carried out at the University of Bari in a Mediterranean greenhouse heated by a polygeneration system, composed of a solar system and an air-water heat pump. Three localized heating systems were tested to transfer thermal energy close to plants of Roman lettuce. Heating pipes were placed inside the cultivation substrate in the underground pipe system and on the cultivation substrate in the laid pipe system. The third system consists of metal plates heated by steel tubes and placed in the aerial area of plants. A weather climatic station and a sensor system interfaced with a data logger for continuous data acquisition and storage were used. The plate system was the best for air temperature rising, as it allowed an increase of 3.6% compared to the set-up without any localised heating system. The underground pipe system was the best for the soil heating, as it achieved a temperature increase of 92%. Localized soil heating systems contributed significantly to an earlier harvest by almost 2 weeks.
Journal of Agricultural Engineering, Volume 52; https://doi.org/10.4081/jae.2021.1187
Fertigation can be a suitable technique for utilizing digestate, minimizing nitrogen losses, and contributing to circularity within a farming system. For this purpose, digestate usually is first processed with a screw-press separator. However, further filtration is required to remove particles that could clog the nozzles of drip or sprinkling irrigation systems. Advanced filtration can be obtained using mechanical separation with screens having openings of 100- 300 μm. This operation can be another source of ammonia emission, but this aspect has not been adequately investigated. This study aimed to address this knowledge gap by evaluating the emissions from three different filtration systems for digestate. The study was conducted in three different farms located in Lombardy (Italy) using digestate to fertigate maize by drip irrigation (two farms) and pivot irrigation (one farm). Ammonia emissions were measured with passive samplers and the fluxes were examined using an inverse dispersion model implemented in Windtrax software. The emissions were measured both when the filtration systems were in operation and when they were switched off. Ammonia emissions (mean values between 375 and 876 μg NH3/m2/s) tended to increase during operation of the filtration systems. However, no significant differences were found in the emissions from active and inactive equipment on any of the farms. The emissions from the filtration systems were higher than from a storage tank (22-67 μg NH3/m2/s). However, the mean emissions amounted to only 0.3% of the nitrogen content of the digestate. These emissions can be considered irrelevant in the context of the whole management scheme for digestate. This work provides a first insight on ammonia emissions arising from advanced filtration of digestate, with specific reference to Po Valley farming systems. Further studies are required to improve knowledge about emissions from the entire digestate management process, including the treatments required for specific application techniques.
Journal of Agricultural Engineering, Volume 52; https://doi.org/10.4081/jae.2021.1167
Thermal weed control plays an important role in managing weeds in synthetic herbicide-free systems, particularly in organic agriculture and in urban areas where synthetic herbicides are prohibited. This study compares the impact on weed control of increased doses of hot water and hot foam (i.e. 0, 0.67, 1.67, 3.33, 5.00, 6.67 and 8.33 kg m–2). The doses were applied using the same machine. The temperatures, weed control effectiveness, weed regrowth after the death of the aboveground vegetative weed tissues, and weed dry biomass 30 days after the treatments were studied in two experimental fields with a different weed composition (i.e. Site I and Site II). The results showed that difficult weeds to control, such as Cynodon dactylon (L.) Pers., Digitaria sanguinalis (L.) Scop. and Taraxacum officinale Weber, like all the other species in the initial weed populations in the two experiments, died after lower doses of hot foam compared to hot water. Adding foam to hot water made it possible to lower the required dose of water by at least 2.5-fold compared to hot water used alone. By insulating the weeds, the foam led to higher peak temperatures and slower temperature decay, thus determining an effective weed control with lower doses compared to hot water. Starting from 11 days and 16 days after treatments (for Site I and Site II, respectively), there were no statistically significant differences in weed regrowth between hot foam and hot water at all the doses applied. There were no differences between the dry biomass of weeds collected 30 days after treatments when the same doses of hot foam and hot water were used.
Journal of Agricultural Engineering, Volume 52; https://doi.org/10.4081/jae.2021.1144
Controlled traffic farming allows to minimize traffic-induced soil compaction by a permanent separation of the crop zone from the traffic lanes used by wide span tractors. The Authors developed an agricultural wide span vehicle equipped with a skid equipment for turning and an automatic driving system prototype based on a laser beam. The aim of this work was to study the kinematic conditions that control the steering of this machine. Furthermore, the accuracy and the maximum delay time of the signal transmission by the automatic driving system of the set-up was also assessed. In comparison with crawler tractors, the turning of the agricultural wide span vehicle needs a smaller difference in the moments applied to its right- and left-side wheels. For the predetermined accuracy of the beam position relative to the plant rows, ±ds = ±0.025 m, the accuracy of the direction of the laser beam at a distance S=200 m should not be more than ±0.07° and ±0.0014°, considering a run length of 1000 m. Furthermore, at a speed V=2.5 m s–1 a trajectory deviation φ≤5° requires a topmost delay time of the control signal of Δtmax=0.11 s is required.