Special Issue "Selected Papers from 10th Iberian Agroengineering Congress"

A special issue of Agronomy (ISSN 2073-4395).

Deadline for manuscript submissions: closed (25 November 2019).

Special Issue Editors

Dr. Pablo Martín-Ramos
Website SciProfiles
Guest Editor
Department of Agricultural and Environmental Sciences, EPS, Instituto Universitario de Investigación en Ciencias Ambientales de Aragón (IUCA), Universidad de Zaragoza, Carretera de Cuarte, s/n, 22071 Huesca, Spain
Interests: sensors and actuators; biorrefineries; photocatalysis; waste management and valorization; soil pollution; life cycle analysis; nanomaterials applied to agriculture
Special Issues and Collections in MDPI journals
Prof. Francisco J. García-Ramos
Website
Guest Editor
Escuela Politécnica Superior - Campus de Huesca, University of Zaragoza, Carretera de Cuarte, s/n, 22071 Huesca, Spain
Special Issues and Collections in MDPI journals
Prof. José Antonio Cuchí-Oterino
Website
Guest Editor
Escuela Politécnica Superior - Campus de Huesca, University of Zaragoza, Carretera de Cuarte, s/n, 22071 Huesca, Spain
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

In 2017, the Food and Agriculture Organization (FAO) issued a report on the challenges that Agriculture is facing and will face into the 21st century, which can be summarized in one question: will we be able to sustainably and effectively feed everyone by 2050 and beyond, while meeting the additional demand for agricultural commodities due to non-food uses? Agricultural engineers can contribute in this process by releasing the biological and technical constraints on crop and animal productivity, reducing the contribution of the agricultural sector to environmental degradation, and enabling agricultural practices to adapt to environmental changes. To achieve optimal results for agribusiness and the society, the expertise of agricultural engineers must be integrated with expertise from other sciences: breakthrough technologies are needed for agricultural enterprises to meet the increasing list of standards and norms in the areas of energy, animal welfare, product quality, water, and volatile emissions. Recognition of trends in society and networking and participation in debates have thus become important activities for agricultural engineers.
The Iberian Agroengineering Congress series brings together Spanish and Portuguese engineers, researchers, educators and practitioners to present and discuss innovations, trends, and solutions to the aforementioned challenges in the interdisciplinary field of Agricultural and Biosystems Engineering. This biennial congress, jointly organized by the Spanish Society of Agroengineering and the Specialized Section of Rural Engineering of the Sociedade de Ciências Agrárias de Portugal, is an excellent opportunity to network and discuss future developments. In its 10th edition, the Congress will be held from 3-6 September in Huesca (Spain), at the Escuela Politécnica Superior, located on the Huesca Campus of the University of Zaragoza. The topics of the Congress include the main areas of Agricultural Engineering: Mechanization; soils and water; animal production technology and aquaculture; rural constructions; energy; information technologies and process control; projects, environment, and territory; postharvest technology; educational innovation in agroengineering. Additional information can be found at http://agroing2019.org.

Dr. Pablo Martín-Ramos
Prof. Francisco J. García-Ramos
Prof. José Antonio Cuchí-Oterino
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Agronomy is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Agronomy
  • crop
  • food systems
  • irrigation and drainage
  • renewable energy
  • rural engineering
  • postharvest
  • precision farming
  • sustainable agriculture
  • technology

Published Papers (27 papers)

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Research

Open AccessArticle
Climate Changes Challenges to the Management of Mediterranean Montado Ecosystem: Perspectives for Use of Precision Agriculture Technologies
Agronomy 2020, 10(2), 218; https://doi.org/10.3390/agronomy10020218 - 03 Feb 2020
Cited by 2
Abstract
Montado is an agro-silvo-pastoral system characterized by a high complexity as a result of the interactions between climate, soil, pasture, trees, and animals. It is in this context that management decisions must be made, for example with respect to soil fertilization, grazing, or [...] Read more.
Montado is an agro-silvo-pastoral system characterized by a high complexity as a result of the interactions between climate, soil, pasture, trees, and animals. It is in this context that management decisions must be made, for example with respect to soil fertilization, grazing, or animal supplementation. In this work, the effect of the tree canopy on the spatial and temporal variability of the soil and productivity, quality, and floristic composition of the pasture was evaluated. Precision agriculture (PA) technologies for monitoring soil and pasture were also evaluated. The study was carried out between October 2015 and June 2018 in an experimental field of 2.3 ha. The results showed: (i) The positive impact of trees and animal grazing on soil fertility; (ii) the influence of inter-annual variability of precipitation on the pattern of pasture vegetative cycle; (iii) the positive effect of trees in pasture quality; (iv) the negative effect of trees in pasture productivity; (v) the role of pasture floristic composition as an indicator of soil limitations or climatic changes; (vi) the potential of technologies associated with the concept of PA as express tools to decision making support and for the optimization of the herbaceous stratum and the dynamic management of grazing in this ecosystem in a holistic and sustainable form. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Efficiency of an Integrated Purification System for Pig Slurry Treatment under Mediterranean Climate
Agronomy 2020, 10(2), 208; https://doi.org/10.3390/agronomy10020208 - 02 Feb 2020
Abstract
The intensification of pig production is considered a risky activity for the environment when the generated pig slurry is not adequately treated. In addition, intensive agriculture practices where pig slurry is applied to the cropland could cause nitrate leaching, salinization, and soil pollution [...] Read more.
The intensification of pig production is considered a risky activity for the environment when the generated pig slurry is not adequately treated. In addition, intensive agriculture practices where pig slurry is applied to the cropland could cause nitrate leaching, salinization, and soil pollution (heavy metals and pathogens), thus the development of an eco-friendly system for pig slurry treatment is essential to avoid undesirable environmental impacts. The main objective of this study was to assess the efficiency of an integrated purification system (IPS) for treating pig slurry. The system included a pretreatment module (raw pig slurry tank, phase separator, aeration tank, and settlement tank), constructed wetlands (CWs) that included an unplanted cell and a planted cell, and a storage pond (SP). Pig slurry samples from the pretreatment modules, CWs, and SP were collected in triplicate and physic-chemical and microbial analyses were performed. Results showed that the pretreatment modules decreased the total suspended solids (TSS), total nitrogen (TN), and total phosphorus (TP) concentrations in the liquid fraction. Higher total nitrogen removal was reported in the planted cell, which decreased from 4.0 g L−1 to 1.9 g L−1 in the inflow and outflow, respectively. Total efficiencies over 85% were found in the planted and unplanted cells for TSS, Kjeldahl nitrogen (KN), chemical oxygen demand (COD), and TP. Microbial parameters were eliminated after the treatment in the planted cell. Therefore, the results indicated that filtration (pretreatment), purification (constructed wetland), and bioremediation (storage pond) constituted an appropriate IPS for treating pig slurry. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Acquiring Plant Features with Optical Sensing Devices in an Organic Strip-Cropping System
Agronomy 2020, 10(2), 197; https://doi.org/10.3390/agronomy10020197 - 01 Feb 2020
Abstract
The SUREVEG project focuses on improvement of biodiversity and soil fertility in organic agriculture through strip-cropping systems. To counter the additional workforce a robotic tool is proposed. Within the project, a modular proof of concept (POC) version will be produced that will combine [...] Read more.
The SUREVEG project focuses on improvement of biodiversity and soil fertility in organic agriculture through strip-cropping systems. To counter the additional workforce a robotic tool is proposed. Within the project, a modular proof of concept (POC) version will be produced that will combine detection technologies with actuation on a single-plant level in the form of a robotic arm. This article focuses on the detection of crop characteristics through point clouds obtained with two lidars. Segregation in soil and plants was successfully achieved without the use of additional data from other sensor types, by calculating weighted sums, resulting in a dynamically obtained threshold criterion. This method was able to extract the vegetation from the point cloud in strips with varying vegetation coverage and sizes. The resulting vegetation clouds were compared to drone imagery, to prove they perfectly matched all green areas in said image. By dividing the remaining clouds of overlapping plants by means of the nominal planting distance, the number of plants, their volumes, and thereby the expected yields per row could be determined. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Treatment of WASTEWATER from the Tannery Industry in a Constructed Wetland Planted with Phragmites australis
Agronomy 2020, 10(2), 176; https://doi.org/10.3390/agronomy10020176 - 26 Jan 2020
Abstract
Constructed wetlands (CWs) can remove a high amount of pollutants from wastewater, and therefore play an important role in water purification. In this study, a pilot system to improve the traditional treatment of industrial wastewater from the tannery industry was tested. The main [...] Read more.
Constructed wetlands (CWs) can remove a high amount of pollutants from wastewater, and therefore play an important role in water purification. In this study, a pilot system to improve the traditional treatment of industrial wastewater from the tannery industry was tested. The main objective of this research was to remove nitrogen, phosphorus, boron, and chromium from a tannery’s industrial wastewater using a horizontal subsurface flow constructed wetland (HSSFCW) formed from three cells, planted with Phragmites australis and operated in batch mode as an ecofriendly system. P. australis was selected due to its ability to adapt to climatic conditions, its wetland and management characteristics, and its high capacity for pollutant absorption. The concentrations of total Kjeldahl nitrogen (TKN), total phosphorus (TP), boron (B), and chromium (Cr) were analyzed in both wastewater and purified water, and the removal efficiencies were calculated. In addition, both the absorption capacity of P. australis in the aerial and root parts and the adsorption capacity of substrates (gravel and washed sand) were analyzed. Results showed that the concentrations of TP and Cr decreased in the wastewater at both hydraulic retention times (HRTs) tested (3 and 7 days), with 3 days being the most effective, showing removal efficiency values of 78% and 48% for TP and Cr, respectively. However, concentrations of TKN and B were not statistically reduced at either HRTs. Regarding the absorption capacity of P. australis, the highest absorption efficiencies for TKN and TP were reported at 7 days in the aerial part of the plants. In contrast, B was retained in roots at HRT of 3 days. Finally, Cr was more significantly absorbed at 3 days by P. australis. Moreover, the substrates also played important roles in the adsorption of nitrogen and boron. Therefore, CWs planted with P. australis could be used as an ecofriendly technique to the reduce pollution load of the wastewater from tannery industry, especially for P and Cr, although in order to increase the removal efficiency of B and N, the combination with other plant species and different retention times should be tested. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
A Mixed Data-Based Deep Neural Network to Estimate Leaf Area Index in Wheat Breeding Trials
Agronomy 2020, 10(2), 175; https://doi.org/10.3390/agronomy10020175 - 26 Jan 2020
Cited by 1
Abstract
Remote and non-destructive estimation of leaf area index (LAI) has been a challenge in the last few decades as the direct and indirect methods available are laborious and time-consuming. The recent emergence of high-throughput plant phenotyping platforms has increased the need to develop [...] Read more.
Remote and non-destructive estimation of leaf area index (LAI) has been a challenge in the last few decades as the direct and indirect methods available are laborious and time-consuming. The recent emergence of high-throughput plant phenotyping platforms has increased the need to develop new phenotyping tools for better decision-making by breeders. In this paper, a novel model based on artificial intelligence algorithms and nadir-view red green blue (RGB) images taken from a terrestrial high throughput phenotyping platform is presented. The model mixes numerical data collected in a wheat breeding field and visual features extracted from the images to make rapid and accurate LAI estimations. Model-based LAI estimations were validated against LAI measurements determined non-destructively using an allometric relationship obtained in this study. The model performance was also compared with LAI estimates obtained by other classical indirect methods based on bottom-up hemispherical images and gaps fraction theory. Model-based LAI estimations were highly correlated with ground-truth LAI. The model performance was slightly better than that of the hemispherical image-based method, which tended to underestimate LAI. These results show the great potential of the developed model for near real-time LAI estimation, which can be further improved in the future by increasing the dataset used to train the model. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Water Balance and Nitrate and Salt Exports from a Saline–Sodic Irrigation District in Castelflorite (Huesca, NE Spain)
Agronomy 2020, 10(2), 165; https://doi.org/10.3390/agronomy10020165 - 23 Jan 2020
Abstract
In the current context of climate change, there is growing interest in the optimization of water management in irrigated areas, in semi-arid environments. The design of adequate adaptation and mitigation measures requires specific data at different scales of the water management hierarchy, up [...] Read more.
In the current context of climate change, there is growing interest in the optimization of water management in irrigated areas, in semi-arid environments. The design of adequate adaptation and mitigation measures requires specific data at different scales of the water management hierarchy, up to basin level. In this work, the irrigation and drainage system of San Pedro de Castelflorite Irrigation Community (Huesca province, NE Spain), first set up as a flood irrigation system around 1970 and then modernized to sprinkler irrigation around 2008, was studied over two irrigation seasons. The land in this basin, with a surface of 11,450 ha, is affected by severe sodicity problems, which impedes cultivation in large areas. Most of the drainage water discharges into Clamor Vieja ravine, in which the quantity and quality of drainage, using water, salt, and nitrogen balances, were monitored. The water regime was found to be essentially regulated by irrigation. From the water balance, the consumed and the recoverable fractions were estimated at 76% and 23%, respectively, and the depleted beneficial fraction for the irrigated area at 73%. A predominance of salt dissolution processes over precipitation processes was found, with salt exports of approximately 2000 kg ha−1·year−1. The nitrogen exported by the drainage water was 7 kg N·ha−1·year−1. This value, remarkably lower than those reported for nearby basins in the central Ebro valley, can be attributed to the flooding of rice fields and to the low permeability of the soils present in this basin, which would hamper nitrate washing through the soil profile. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Instrumental Procedures for the Evaluation of Juiciness in Peach and Nectarine Cultivars for Fresh Consumption
Agronomy 2020, 10(2), 152; https://doi.org/10.3390/agronomy10020152 - 21 Jan 2020
Abstract
There is growing interest within the peach and nectarine markets in obtaining and selling ready-to-eat fruits. For this, pre-ripening protocols are being applied, which do not always result in sufficiently juicy fruits. Therefore, the aim of this study is the development of objective [...] Read more.
There is growing interest within the peach and nectarine markets in obtaining and selling ready-to-eat fruits. For this, pre-ripening protocols are being applied, which do not always result in sufficiently juicy fruits. Therefore, the aim of this study is the development of objective instrumental procedures for quantification of the juiciness attributes of these fruits. In this work, we evaluated the juiciness of more than 2000 fruits belonging to 20 of the varieties of greatest interest in the southeast of Spain. An instrumental mechanical procedure based on the confined compression of a pulp specimen of known volume was designed and optimized. Instrumental juiciness was defined as the wet area (cm2) on an absorbent paper located under the compression probe. This test allowed for the defining of objective thresholds for the identification of juicy fruits; 90% of the fruits with areas higher than 5.4 cm2 were considered to be juicy. Complementarily, non-invasive supervision by near-infrared (NIR) spectroscopy, based on pulp structural changes during ripening, allowed for estimation of the instrumental juiciness with coefficients of correlation above 0.83. The results of these instrumental procedures contribute to supporting decision tools in the logistics chain of stone fruits. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Performance Evaluation of Two Commercially Available Portable Spectrometers to Non-Invasively Determine Table Grape and Peach Quality Attributes
Agronomy 2020, 10(1), 148; https://doi.org/10.3390/agronomy10010148 - 19 Jan 2020
Abstract
Near-infrared (NIR) spectroscopy has been used to non-destructively and rapidly evaluate the quality of fresh agricultural produce. In this study, two commercially available portable spectrometers (F-750: Felix Instruments, WA, USA; and SCiO: Consumer Physics, Tel Aviv, Israel) were evaluated in the wavelength range [...] Read more.
Near-infrared (NIR) spectroscopy has been used to non-destructively and rapidly evaluate the quality of fresh agricultural produce. In this study, two commercially available portable spectrometers (F-750: Felix Instruments, WA, USA; and SCiO: Consumer Physics, Tel Aviv, Israel) were evaluated in the wavelength range between 740 and 1070 nm to non-invasively predict quality attributes, including the dry matter (DM), and total soluble solids (TSS) content of three fresh table grape cultivars (‘Autumn Royal’, ‘Timpson’, and ‘Sweet Scarlet’) and one peach cultivar (‘Cassie’). Prediction models were developed using partial least-square regression (PLSR) to correlate the NIR absorbance spectra with the invasive quality measurements. In regard to grapes, the best DM prediction models yielded an R2 of 0.83 and 0.81, a ratio of standard error of performance to standard deviation (RPD) of 2.35 and 2.29, and a root mean square error of prediction (RMSEP) of 1.40 and 1.44; and the best TSS prediction models generated an R2 of 0.97 and 0.95, an RPD of 5.95 and 4.48, and an RMSEP of 0.53 and 0.70 for the F-750 and SCiO spectrometers, respectively. Overall, PLSR prediction models using both spectrometers were promising to predict table grape quality attributes. Regarding peach, the PLSR prediction models did not perform as well as in grapes, as DM prediction models resulted in an R2 of 0.81 and 0.67, an RPD of 2.24 and 1.74, and an RMSEP of 1.28 and 1.66; and TSS resulted in an R2 of 0.62 and 0.55, an RPD of 1.55 and 1.48, and an RMSEP of 1.19 and 1.25 for the F-750 and SCiO spectrometers, respectively. Overall, the F-750 spectrometer prediction models performed better than those generated by using the SCiO spectrometer data. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
CitrusYield: A Dashboard for Mapping Yield and Fruit Quality of Citrus in Precision Agriculture
Agronomy 2020, 10(1), 128; https://doi.org/10.3390/agronomy10010128 - 15 Jan 2020
Abstract
The application of new technologies in precision agriculture offers the possibility to link information to very specific crop locations. The spatial representation of these agricultural data through yield and fruit quality maps allows for crop management in a precise way that means that [...] Read more.
The application of new technologies in precision agriculture offers the possibility to link information to very specific crop locations. The spatial representation of these agricultural data through yield and fruit quality maps allows for crop management in a precise way that means that agricultural operations may be carried out considering intraorchard variability, thus resulting in greater efficiency. The aim of this work was to advance the development of new tools for the generation of yield and quality maps for precision agriculture. A new tool was implemented for citrus through a dashboard called CitrusYield that integrates the requirements demanded by technicians and farmers in terms of spatial distribution and the quality of their citrus production. The data for testing were collected by a prototype of a citrus harvest-assist platform. In order to obtain maps showing heterogeneity of production, an experimental plot with different varieties and variable production was chosen. The maps, tables and graphs showing different crop data were generated automatically by CitrusYield from the analysis of the data collected. The main advantage of knowing the differences in production between the swaths and areas inside the crop is to provide the grower with precise information to make accurate decisions for localised crop management, such as fertilisation, irrigation, pest and disease control, etc. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Evolution of NH3 Concentrations in Weaner Pig Buildings Based on Setpoint Temperature
Agronomy 2020, 10(1), 107; https://doi.org/10.3390/agronomy10010107 - 11 Jan 2020
Abstract
Ammonia (NH3) concentration has seldom been used for environmental control of weaner buildings despite its impact on environment, animal welfare, and workers’ health. This paper aims to determine the effects of setpoint temperature (ST) on the daily evolution of NH3 [...] Read more.
Ammonia (NH3) concentration has seldom been used for environmental control of weaner buildings despite its impact on environment, animal welfare, and workers’ health. This paper aims to determine the effects of setpoint temperature (ST) on the daily evolution of NH3 concentration in the animal-occupied zone. An experimental test was conducted on a conventional farm, with ST between 23 °C and 26 °C. NH3 concentrations in the animal-occupied zone were dependent on ST insofar as ST controlled the operation of the ventilation system, which effectively removed NH3 from the building. The highest NH3 concentrations occurred at night and the lowest concentrations occurred during the daytime. Data were fitted to a sinusoidal model using the least squares setting (LSS) and fast Fourier transform (FFT), which provided R2 values between 0.71 and 0.93. FFT provided a better fit than LSS, with root mean square errors (RMSEs) between 0.09 ppm for an ST of 23 °C and 0.55 ppm for an ST of 25 °C. A decrease in ST caused a delay in the wave and a decrease in wave amplitude. The proposed equations can be used for modeling NH3 concentrations and implemented in conventional controllers for real-time environmental control of livestock buildings to improve animal welfare and productivity. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Effects of Biochar Application in a Sorghum Crop under Greenhouse Conditions: Growth Parameters and Physicochemical Fertility
Agronomy 2020, 10(1), 104; https://doi.org/10.3390/agronomy10010104 - 10 Jan 2020
Abstract
Application of biochar from vine shoots (Vitis vinifera L.) as an organic amendment in the soil is an alternative agricultural management of interest. The behavior of this type of amendment in the soil requires more information to adjust the pyrolysis conditions in [...] Read more.
Application of biochar from vine shoots (Vitis vinifera L.) as an organic amendment in the soil is an alternative agricultural management of interest. The behavior of this type of amendment in the soil requires more information to adjust the pyrolysis conditions in order to obtain a high-quality biochar. The aim of this work is determining the influence of the application of this type of biochar on the soil-plant system. For this purpose, an agronomic test was performed in greenhouse pots. A randomized tri-factorial block design was adopted with the following factors: final pyrolysis temperature (400 and 600 °C), application rate (0 wt. % as a control, 1.5 and 3 wt. %) and texture of the growing media (sandy-loam and clay-loam origin). The selected crop was sorghum (Sorghum bicolor L. Moench), the development and production of which was evaluated during two complete growing cycles under greenhouse conditions. Application of biochar produced at 400 °C significantly increased plants roots dry weight in the sandy-loam growing substrate (52% compared to the control). Grain production was also significantly affected by biochar application, showing better results after addition of biochar produced at 400 °C. Water holding capacity and K, Ca, and Mg contents were enhanced by biochar addition, with evident effects of the application ratios for some of these variables. The effect on the pH of substrates in the sandy-loam texture was weak; however, a significant decrease was observed after the addition of biochar produced at 600 °C. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
On-Farm Evaluation of Prescription Map-Based Variable Rate Application of Pesticides in Vineyards
Agronomy 2020, 10(1), 102; https://doi.org/10.3390/agronomy10010102 - 10 Jan 2020
Cited by 2
Abstract
Canopy characteristics are crucial for accurately and safely determining the pesticide quantity and volume of water used for spray applications in vineyards. The inevitably high degree of intraplot variability makes it difficult to develop a global solution for the optimal volume application rate. [...] Read more.
Canopy characteristics are crucial for accurately and safely determining the pesticide quantity and volume of water used for spray applications in vineyards. The inevitably high degree of intraplot variability makes it difficult to develop a global solution for the optimal volume application rate. Here, the design procedure of, and the results obtained from, a variable rate application (VRA) sprayer are presented. Prescription maps were generated after detailed canopy characterization, using a multispectral camera embedded on an unmanned aerial vehicle, throughout the entire growing season in Torrelavit (Barcelona) in four vineyard plots of Chardonnay (2.35 ha), Merlot (2.97 ha), and Cabernet Sauvignonn (4.67 ha). The maps were obtained by merging multispectral images with information provided by DOSAVIÑA®, a decision support system, to determine the optimal volume rate. They were then uploaded to the VRA prototype, obtaining actual variable application maps after the application processes were complete. The prototype had an adequate spray distribution quality, with coverage values in the range of 20–40% and exhibited similar results in terms of biological efficacy on powdery mildew compared to conventional (and constant) application volumes. The VRA results demonstrated an accurate and reasonable pesticide distribution, with potential for reduced disease damage even in cases with reduced amounts of plant protection products and water. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessCommunication
A New Technique for Improved Use of Thermal Energy from Waste Effluents
Agronomy 2020, 10(1), 97; https://doi.org/10.3390/agronomy10010097 - 09 Jan 2020
Abstract
Energy sustainability and environmental protection in general are at the heart of engineering and industry discussions. Countless efforts have been devoted to improving the energy efficiency of industrial processes and specifically to harnessing their waste energy sources. One such source is waste from [...] Read more.
Energy sustainability and environmental protection in general are at the heart of engineering and industry discussions. Countless efforts have been devoted to improving the energy efficiency of industrial processes and specifically to harnessing their waste energy sources. One such source is waste from agro-industrial processes, which is frequently characterized by increased temperatures and high polluting potential. There are multiple available choices for exploiting energy from such waste, but this paper proposes a new alternative technique that substantially improves the efficiency. Based on the technology of leveraging a hot liquid effluent for heating a process fluid, this system introduces a third liquid to be revalorized by drying that is placed in between the hot and cold liquids. By adding stirrers inside the heat exchanger, the thermal resistance of the third fluid is reduced to a negligible level. Thus, this system has almost the same advantages as the previous one, but with the added benefit that it allows drying of a third fluid. One of the specific applications of this proposed technology is using heat from waste effluents to obtain dried food products. In the present work, it was used to dry slaughterhouse blood to obtain so-called “blood meal”, a product with a high added value that is used as pet food or organic fertilizer, and also has many other industrial applications. As shown here, the new technique outperforms existing alternatives in terms of energy efficiency and economic profitability. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Prediction of Horizontal Daily Global Solar Irradiation Using Artificial Neural Networks (ANNs) in the Castile and León Region, Spain
Agronomy 2020, 10(1), 96; https://doi.org/10.3390/agronomy10010096 - 09 Jan 2020
Abstract
This article evaluates horizontal daily global solar irradiation predictive modelling using artificial neural networks (ANNs) for its application in agricultural sciences and technologies. An eight year data series (i.e., training networks period between 2004–2010, with 2011 as the validation year) was measured at [...] Read more.
This article evaluates horizontal daily global solar irradiation predictive modelling using artificial neural networks (ANNs) for its application in agricultural sciences and technologies. An eight year data series (i.e., training networks period between 2004–2010, with 2011 as the validation year) was measured at an agrometeorological station located in Castile and León, Spain, owned by the irrigation advisory system SIAR. ANN models were designed and evaluated with different neuron numbers in the input and hidden layers. The only neuron used in the outlet layer was the global solar irradiation simulated the day after. Evaluated values of the input data were the horizontal daily global irradiation of the current day [H(t)] and two days before [H(t−1), H(t−2)], the day of the year [J(t)], and the daily clearness index [Kt(t)]. Validated results showed that best adjustment models are the ANN 7 model (RMSE = 3.76 MJ/(m2·d), with two inputs ([H(t), Kt(t)]) and four neurons in the hidden layer) and the ANN 4 model (RMSE = 3.75 MJ/(m2·d), with two inputs ([H(t), J(t)]) and two neurons in the hidden layer). Thus, the studied ANN models had better results compared to classic methods (CENSOLAR typical year, weighted moving mean, linear regression, Fourier and Markov analysis) and are practically easier as they need less input variables. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Sugar Beet Agronomic Performance Evolution in NW Spain in Future Scenarios of Climate Change
Agronomy 2020, 10(1), 91; https://doi.org/10.3390/agronomy10010091 - 09 Jan 2020
Abstract
Changes in environmental conditions resulting from Climate Change are expected to have a major impact on crops. In order to foresee adaptation measures and to minimize yield decline, it is necessary to estimate the effect of those changes on the evapotranspiration and on [...] Read more.
Changes in environmental conditions resulting from Climate Change are expected to have a major impact on crops. In order to foresee adaptation measures and to minimize yield decline, it is necessary to estimate the effect of those changes on the evapotranspiration and on the associated irrigation needs of crops. In the study presented herein, future conditions extracted from RCP4.5 scenario of IPCC, particularized for Castilla-y-León (Spain), were used as inputs for FAO crop simulation model (AquaCrop) to estimate sugar beet agronomic performance in the medium-term (2050 and 2070). A regional analysis of future trends in terms of yield, biomass and CO2 sequestration was carried out. An annual ET0 increase of up to 200 mm was estimated in 2050 and 2070 scenarios, with ETc increases of up to 40 mm/month. At current irrigation levels, temperature rise would be accompanied by a 9% decrease in yield and a ca. 6% decrease in assimilated CO2 in the 2050 and 2070 scenarios. However, it is also shown that the implementation of adequate adaptation measures, in combination with a more efficient irrigation management, may result in up to 17% higher yields and in the storage of between 9% and 13% higher amounts of CO2. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Hyperspectral Imaging to Assess the Presence of Powdery Mildew (Erysiphe necator) in cv. Carignan Noir Grapevine Bunches
Agronomy 2020, 10(1), 88; https://doi.org/10.3390/agronomy10010088 - 08 Jan 2020
Abstract
Powdery mildew is a worldwide major fungal disease for grapevine, which adversely affects both crop yield and produce quality. Disease identification is based on visible signs of a pathogen once the plant has already been infected; therefore, techniques that allow objective diagnosis of [...] Read more.
Powdery mildew is a worldwide major fungal disease for grapevine, which adversely affects both crop yield and produce quality. Disease identification is based on visible signs of a pathogen once the plant has already been infected; therefore, techniques that allow objective diagnosis of the disease are currently needed. In this study, the potential of hyperspectral imaging (HSI) technology to assess the presence of powdery mildew in grapevine bunches was evaluated. Thirty Carignan Noir grape bunches, 15 healthy and 15 infected, were analyzed using a lab-scale HSI system (900–1700 nm spectral range). Image processing was performed to extract spectral and spatial image features and then, classification models by means of Partial Least Squares Discriminant Analysis (PLS-DA) were carried out for healthy and infected pixels distinction within grape bunches. The best discrimination was achieved for the PLS-DA model with smoothing (SM), Standard Normal Variate (SNV) and mean centering (MC) pre-processing combination, reaching an accuracy of 85.33% in the cross-validation model and a satisfactory classification and spatial location of either healthy or infected pixels in the external validation. The obtained results suggested that HSI technology combined with chemometrics could be used for the detection of powdery mildew in black grapevine bunches. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Variety Characterization and Influence of Olive Maturity in Virgin Olive Oils from the Area Assigned to the Protected Designation of Origin “Aceite de la Alcarria” (Spain)
Agronomy 2020, 10(1), 38; https://doi.org/10.3390/agronomy10010038 - 25 Dec 2019
Abstract
In this first contribution to the study of virgin olive oils from the area assigned to the Protected Designation of Origin (PDO) “Aceite de la Alcarria” (Spain), both monovarietal oils obtained under ideal conditions in a pilot plant, as well as blend oils [...] Read more.
In this first contribution to the study of virgin olive oils from the area assigned to the Protected Designation of Origin (PDO) “Aceite de la Alcarria” (Spain), both monovarietal oils obtained under ideal conditions in a pilot plant, as well as blend oils made in the oil mills located in the study area, were characterized. Special interest was focused on the influence of the ripening state of the fruits. The oils from the Castellana variety, the main variety found in the study area, were characterized by a high content of tocopherols, medium oxidative stability and high content in palmitic, palmitoleic and linolenic acids. As the ripening process progresses, the oils lose fruitiness, bitterness, pungency, stability, and some organoleptic defects appear, to the point of lowering the category (from extra virgin to virgin) in some of the Castellana samples. Thus, early collection of olives of this variety is recommended. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
CitrusVol Validation for the Adjustment of Spray Volume in Treatments against Tetranychus urticae in Clementines
Agronomy 2020, 10(1), 32; https://doi.org/10.3390/agronomy10010032 - 24 Dec 2019
Abstract
The optimization of the water volume used to apply pesticides with airblast sprayers is key to reducing water footprint, costs, operational time and drift of pesticides. This study evaluated a new tool (CitrusVol) that adjusts the spray volume to the characteristics of the [...] Read more.
The optimization of the water volume used to apply pesticides with airblast sprayers is key to reducing water footprint, costs, operational time and drift of pesticides. This study evaluated a new tool (CitrusVol) that adjusts the spray volume to the characteristics of the vegetation and the pesticide used to control the two-spotted spider mite Tetranychus urticae in clementine trees. This mite is one of the main citrus pests because it damages fruit before harvest. For this aim, a total of 20 applications against T. urticae were evaluated during two consecutive years in seven commercial orchards. In these orchards, we evaluated: (i) the distribution of the spray in tree canopies, (ii) pest density before and after the treatment, and (iii) fruit damage at harvest when conventional volumes and volumes adjusted with CitrusVol were applied. On average, CitrusVol reduced 36% the water volume used to control T. urticae in the 20 applications. This reduction in the spray volume involved a decrease in the coverage in some parts of the canopy. However, T. urticae density and fruit damage at harvest were similar in trees treated with the adjusted volume calculated with CitrusVol and the volume used by the owners of the orchard. Therefore, the spray volume recommended by CitrusVol is adequate to control T. urticae in clementines. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Nitrates in Groundwater of Small Shallow Aquifers in the Western Side of Hoya de Huesca (NE Spain)
Agronomy 2020, 10(1), 22; https://doi.org/10.3390/agronomy10010022 - 22 Dec 2019
Abstract
Nitrate is one of the most common groundwater contaminants in rural areas. In this work, the presence of high levels of nitrate in groundwater of the aquifers of the west part of Hoya de Huesca County (NE Spain) has been studied by coupling [...] Read more.
Nitrate is one of the most common groundwater contaminants in rural areas. In this work, the presence of high levels of nitrate in groundwater of the aquifers of the west part of Hoya de Huesca County (NE Spain) has been studied by coupling hydrogeological information with water sampling techniques through a wide areal sampling of 90 surface water and groundwater points belonging to several aquifers. The results showed a general hydrochemistry of calcium carbonate to calcium sulfate waters. Unlike other case studies in Mediterranean areas, in which nitrate pollution was associated with irrigated crops, the highest concentrations in the present study were found in dry farming areas in which winter cereal is grown. A monthly nitrate level monitoring, conducted in 21 selected points between 2016 and 2017, showed that the nitrate evolution pattern followed the N fertilizer application schedules in the sampling points in which the highest concentrations were recorded, whereas an annual regularity could be observed in the sampling points with low nitrate levels. The compilation of data for 16 selected points since 1990 shows that the problem is persistent and points to the need of implementing new aquifer pollution control measures, since the ones currently in force have not been successful. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Experimental Evaluation of a New Giant Reed (Arundo Donax L.) Composite Using Citric Acid as a Natural Binder
Agronomy 2019, 9(12), 882; https://doi.org/10.3390/agronomy9120882 - 12 Dec 2019
Cited by 3
Abstract
The raw materials used to manufacture thermal insulation in buildings consume a large amount of energy and are not generally biodegradable, which means it is necessary to increase the use of renewable, eco-friendly resources such as plant fibers in order to reduce the [...] Read more.
The raw materials used to manufacture thermal insulation in buildings consume a large amount of energy and are not generally biodegradable, which means it is necessary to increase the use of renewable, eco-friendly resources such as plant fibers in order to reduce the environmental problems this generates. The wood adhesives developed by the petrochemical industry offer excellent performance and are affordable. However, their use has an expiry date and in the future they will be rejected due to the environmental and health problems they can cause. The objective of this work was to develop a new eco-friendly biocomposite that could be used for thermal insulation in buildings. Boards were manufactured from giant reed particles with a particle size of 2 to 4 mm, using 5 and 10% by weight of citric acid as a natural binder. Experiments were then carried out to investigate the effect of board density on mechanical, physical, and thermal properties. A new type of composite was obtained with a thermal conductivity of 0.081–0.093 W/m K, which makes it suitable as an insulating material. The boards with a density of 850 kg/m3 had a modulus of rupture (MOR) of 12.5 N/mm2, a modulus of elasticity (MOE) of 2440 N/mm2, and an internal bonding strength (IB) of 0.61 N/mm2, and they could be used as insulation panels for divisions and enclosures in buildings. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Fire Risks Associated with Combine Harvesters: Analysis of Machinery Critical Points
Agronomy 2019, 9(12), 877; https://doi.org/10.3390/agronomy9120877 - 11 Dec 2019
Abstract
Combine harvesters are an important cause of fires worldwide. The purpose of this work has been to investigate the critical points associated with the risk of fire, identified through a survey distributed to combine owners in Aragon (Spain). Information was collected on the [...] Read more.
Combine harvesters are an important cause of fires worldwide. The purpose of this work has been to investigate the critical points associated with the risk of fire, identified through a survey distributed to combine owners in Aragon (Spain). Information was collected on the technical characteristics of the machines and, when appropriate, on the characteristics of the generated fires (crop, use of straw chopper, point in which the fire was originated, etc.). Based on the survey data, relationships between the characteristics of the machine and the ignition of a fire were analyzed, and the points of the harvester in which the fire originated were investigated. A statistically significant relationship of fire risk was only found with the number of hectares harvested, in such a way that the risk would be especially high for machines with more than 6000 accumulated ha. 32% of the fires were originated in the engine zone, compared with 31% in the cutting bar and 18% in the bearings and belts. The study was completed with on-site temperature measurements carried out on nine machines in 2018 and 2019, in which temperatures above 250 °C were recorded in the exhaust manifold and in the cutting bar. These temperatures exceeded the ignition thresholds obtained in the flammability studies conducted for wheat residues collected from the harvesters. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Comparison of SHD and Open-Center Training Systems in Almond Tree Orchards cv. ‘Soleta’
Agronomy 2019, 9(12), 874; https://doi.org/10.3390/agronomy9120874 - 11 Dec 2019
Abstract
The increase in the demand for almonds, the development of novel self-fertile and late-flowering varieties, and the establishment of plantations in new irrigated areas have led to significant progress in the productive techniques of almond tree cultivation. One of the most important has [...] Read more.
The increase in the demand for almonds, the development of novel self-fertile and late-flowering varieties, and the establishment of plantations in new irrigated areas have led to significant progress in the productive techniques of almond tree cultivation. One of the most important has been the increase in planting density, due to the development of dwarfing rootstocks. This paper presents a comparison between two training systems with ‘Soleta’ almond cultivar: a super high density (SHD) system using Rootpac-20 dwarfing rootstock versus an open-center training system using GF-677 rootstock. To this end, several parameters related to chlorophyll content (fluorescence and SPAD) and light interception (from photosynthetically active radiation (PAR) measurements) were monitored throughout two vegetative cycles, and other productive conditions (flowering, fruit set and production) were tracked at specific times of the cycle. The open-center system resulted in higher PAR interception than the SHD system, but also in the presence of poorly illuminated fractions of the canopy. Differences were observed between both systems in terms of average fruit weight and yield per canopy volume. Lower yields were obtained in SHD system than in open-center, which may be significantly increased by adapting the inter-row spacing. However, the degree of efficiency in the use of resources or productive inputs, such as irrigation, was favorable to the new SHD training system, so its potential to become a reference system in modern plantations (using over-the-row harvesters similar to those used for vine and olive trees) seems promising. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Study of the Utilisation of Almond Residues for Low-Cost Panels
Agronomy 2019, 9(12), 811; https://doi.org/10.3390/agronomy9120811 - 27 Nov 2019
Abstract
A large amount of research is being carried out to increase the use of renewable and eco-friendly resources like plant fibres for manufacturing new products in order to reduce energy consumption and improve their environmental impact. The almond is a deciduous tree that [...] Read more.
A large amount of research is being carried out to increase the use of renewable and eco-friendly resources like plant fibres for manufacturing new products in order to reduce energy consumption and improve their environmental impact. The almond is a deciduous tree that is native to Mediterranean areas, although nowadays the United States is the world’s main almond producer. The almond fruit has three distinct parts: the inner core or flesh, the hard middle part or shell, and the outer covering of the shell, called the hull (exocarp and mesocarp). This work analyses the use of almond residues for producing eco-friendly particleboards. The ground hull of the almond has been used as a raw material, obtaining 4 different particle sizes. Eight type of board has been manufactured without using any kind of adhesive. The particle size influences some physical and mechanical properties. With particle sizes <0.25 mm it is possible to achieve greater strength in terms of modulus of rupture (MOR): 14.01 N/mm2, modulus of elasticity (MOE): 2295.32 N/mm2 and internal bonding strength (IB): 0.57 N/mm2. This study shows that it is technically possible to manufacture boards with this material without using adhesives. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
CFD Models as a Tool to Analyze the Performance of the Hydraulic Agitation System of an Air-Assisted Sprayer
Agronomy 2019, 9(11), 769; https://doi.org/10.3390/agronomy9110769 - 18 Nov 2019
Cited by 1
Abstract
A computational fluid dynamics (CFD) model of the fluid velocities generated by the agitation system of an air-assisted sprayer was developed and validated by practical experiments in a laboratory. The model was developed considering different settings of the agitation system: Three water levels [...] Read more.
A computational fluid dynamics (CFD) model of the fluid velocities generated by the agitation system of an air-assisted sprayer was developed and validated by practical experiments in a laboratory. The model was developed considering different settings of the agitation system: Three water levels in the tank (1000, 2000, and 3000 L); two different numbers of active nozzles (2 or 4); and three working pressures of the agitation circuit (8, 10, or 12 bar). Actual measurements of the fluid velocity into the tank were taken using an acoustic Doppler velocimeter (ADV). CFD simulations made it possible to estimate fluid velocities at 38% of the measuring points with relative errors of less than 30%. Additionally, the CFD models have allowed the correct prediction of the general behavior of the fluid in the tank considering mean velocities depending on the setting parameters of the agitation system (water level in the tank, hydraulic circuit pressure, and number of active nozzles). Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Behavior of Vine Varieties Resistant to Fungal Diseases in the Somontano Region
Agronomy 2019, 9(11), 738; https://doi.org/10.3390/agronomy9110738 - 10 Nov 2019
Abstract
The vine is highly susceptible to numerous fungal diseases, the incidence and severity of which are increasing because of climate change. To fight them, large amounts of phytosanitary products are generally used, although they entail important economic and environmental costs. The new fungus [...] Read more.
The vine is highly susceptible to numerous fungal diseases, the incidence and severity of which are increasing because of climate change. To fight them, large amounts of phytosanitary products are generally used, although they entail important economic and environmental costs. The new fungus resistant vine varieties (PIWI) constitute one of the most active lines of research on plant material in viticulture and are regarded as a viable solution to respond to the requirements of European Directive 2009/128/EC. In the present work, the evolution and impact of the three main fungal diseases (powdery mildew, downy mildew and botrytis bunch rot) were monitored in plots in the Somontano region (Huesca, Spain), comparing three PIWI varieties (Sauvignon Kretos, Souvignier gris and Muscaris) with a susceptible control variety (Sauvignon blanc) in real field growing conditions over three successive years (2016–2018). The main ampelographic characters of each variety were studied and a weekly follow-up was carried out to track the development of each disease, relating it to climatic variables. Regardless of the climatic conditions (one of the growing seasons was rainy and the other two corresponded to dry years, with differences in the distribution of rainfall), the three PIWI varieties hardly presented any symptoms, demonstrating a high resistance to downy mildew and powdery mildew and even to botrytis. Principal component analysis results pointed to a differential behavior versus the control and treated Sauvignon blanc plants in terms of disease resistance. Based on production results, despite the youth of the plantation, the excellent potential of Sauvignon Kretos variety was observed. However, from the analysis of the quality of wine obtained in microvinifications from these fungus resistant varieties in the second and third year, the one obtained from Muscaris seemed to have the best organoleptic properties. Apart from environmental considerations, given that these fungus resistant varieties can significantly contribute to the sustainability of wineries, they may also respond to the demand of consumers who want zero-pesticide products or of the supporters of ecological products adjusted to European regulations. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Analysis of Factors Affecting the Rearing of Early-Weaned Lambs of Dairy Breeds for the Meat Market
Agronomy 2019, 9(11), 694; https://doi.org/10.3390/agronomy9110694 - 30 Oct 2019
Abstract
Sheep farming makes an important socio-economic contribution to Spain’s rural areas by sustaining farming and employment in less favored regions, but it is a low-profit sector because of high operating and regulatory costs. One possible solution would be to raise for slaughter lambs [...] Read more.
Sheep farming makes an important socio-economic contribution to Spain’s rural areas by sustaining farming and employment in less favored regions, but it is a low-profit sector because of high operating and regulatory costs. One possible solution would be to raise for slaughter lambs from dairy sheep that are not required as replacements. However, the early weaning of these lambs and their artificial rearing generally lead to reduced growth rates and high mortalities. In the work presented herein, three housing systems (slat + heating plate, slat + infrared lamp, and deep-litter + infrared lamp) were tested on 763 lambs over an eight-month period in a farm located in Ejea de los Caballeros (Zaragoza, Spain), with a view to reducing mortality during the period of artificial lactation. The effect of the environmental parameters of the lamb housing on the development of the lambs was evaluated by monitoring environmental (temperature, relative humidity, CO2 and NH3) and productive parameters (weight, average daily gain, and deaths). The results suggested that the combination of deep litter with straw bedding and infrared lamp heating would be the most favorable option, as it led to the highest average daily gain and the lowest percentage of deaths. From the study of the relationship of the initial weight with deaths, a prediction curve was obtained, defining the maximum prices to be paid per lamb as a function of their initial weight to guarantee the profitability of the raising process. This may be regarded as a valuable guidance for Spanish sheep farmers, as it can reduce their economic uncertainty. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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Open AccessArticle
Laboratory Device to Assess the Effect of Mechanical Thinning of Flower Buds, Flowers and Fruitlets Related to Fruitlet Developing Stage
Agronomy 2019, 9(11), 668; https://doi.org/10.3390/agronomy9110668 - 23 Oct 2019
Abstract
Mandarin thinning is done by hand, increasing labor costs and raising total crop production costs. Mechanical thinning has been tested in peaches and other fruits. To achieve the maximum efficiency thinning has to be applied at a specific stage of vegetative development. In [...] Read more.
Mandarin thinning is done by hand, increasing labor costs and raising total crop production costs. Mechanical thinning has been tested in peaches and other fruits. To achieve the maximum efficiency thinning has to be applied at a specific stage of vegetative development. In this research study, the mechanical thinning of ‘Clemenrubi’ mandarin branches during the different fruit development stages have been assessed using a vibratory laboratory device (amplitudes 0.015 and 0.030 m and frequencies 34.8 and 37.8 Hz). Branches with flower buds, flowers, small green fruits, and medium green fruits were tested for 12 weeks, in two different seasons. It was possible to mechanically detach flower buds, flowers, and green fruits using different combinations of amplitudes and frequencies. Removal percentage decreased when increasing retention traction force, according to a logarithmic regression model. A significant increment in equatorial diameter and retention traction force was registered when the fruit setting was finishing, while mass had a similar development with a week delay. During fruit setting (weeks 5, 6, and 7) removal percentage was higher, while the retention force was very low. The first weeks just after the natural thinning could be considered the adequate time for a mechanical thinning operation. Full article
(This article belongs to the Special Issue Selected Papers from 10th Iberian Agroengineering Congress)
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