This page has only limited features, please log in for full access.

Prof. Diego Valera
Engineering Department, University of Almería, 04120 La Cañada, Almería, Spain

Basic Info


Research Keywords & Expertise

0 Desalination
0 Ventilation
0 Water Efficiency
0 Agricultural sustainability
0 Greenhouse Technology

Fingerprints

Ventilation
Desalination
Greenhouse Technology
Climate control

Honors and Awards

The user has no records in this section


Career Timeline

The user has no records in this section.


Short Biography

The user biography is not available.
Following
Followers
Co Authors
The list of users this user is following is empty.
Following: 0 users

Feed

Journal article
Published: 28 April 2021 in Agronomy
Reads 0
Downloads 0

The efficient use of light is one of the most important factors for the development of greenhouse crops. It is increasingly necessary to use film covers that enhance transmittance and the proportion of diffuse light to generate a more homogeneous light distribution. The objective of this study was to evaluate the effect that an experimental film cover with high transmittance and high light diffusivity produces on the microclimate and the growth and yield of tomato crops (Solanum lycopersicum L.), compared with a commercial thermal film cover. The trial was developed during a spring–summer growing cycle in a multispan greenhouse divided into two compartments (sectors) separated by a vertical polyethylene sheet. In the East sector, a commercial film was installed (transmittance of 85% and diffusivity of 60%) and in the West sector, an experimental film was used (transmittance of 90% and diffusivity of 55%). The results show an increase in the marketable yield of 0.25 kg·m−2 in the sector with the experimental film, which represents 3.2% growth with respect to the commercial film. The photosynthetic activity measured in tomato leaves was 21.5% higher in plants growing in the sector with the experimental film, with had the highest transmittance. The increase in radiation transmittance of 14% produced greater photosynthetic activity without generating a higher inside air temperature at the crop level (at the height of 2 m above the floor). However, the mean temperature of the soil surface was statistically higher on the side with the diffuse experimental cover film, as a logical consequence of the higher level of intercepted solar radiation.

ACS Style

María Moreno-Teruel; Francisco Molina-Aiz; Araceli Peña-Fernández; Alejandro López-Martínez; Diego Valera-Martínez. The Effect of Diffuse Film Covers on Microclimate and Growth and Production of Tomato (Solanum lycopersicum L.) in a Mediterranean Greenhouse. Agronomy 2021, 11, 860 .

AMA Style

María Moreno-Teruel, Francisco Molina-Aiz, Araceli Peña-Fernández, Alejandro López-Martínez, Diego Valera-Martínez. The Effect of Diffuse Film Covers on Microclimate and Growth and Production of Tomato (Solanum lycopersicum L.) in a Mediterranean Greenhouse. Agronomy. 2021; 11 (5):860.

Chicago/Turabian Style

María Moreno-Teruel; Francisco Molina-Aiz; Araceli Peña-Fernández; Alejandro López-Martínez; Diego Valera-Martínez. 2021. "The Effect of Diffuse Film Covers on Microclimate and Growth and Production of Tomato (Solanum lycopersicum L.) in a Mediterranean Greenhouse." Agronomy 11, no. 5: 860.

Journal article
Published: 05 March 2021 in Journal of Cleaner Production
Reads 0
Downloads 0

In South-east Spain the implementation of desalinated seawater for irrigation was planned as an alternative water supply for farmers. However, most high-volume desalination plants are underused as farmers’ current demands are lower than was previously expected. In order to develop programmes promoting an effective behavioural shift of farmers toward desalinated water, it is necessary to first explore their preferences and attitudes. This paper shows the results of a survey examining the attitudes and behaviour of farmers toward the use of desalinated seawater for irrigation in the South-east of Spain. The results show the existence of different farmer typologies regarding desalinated seawater use, as well as their preferences and attitudes. The main finding of this study has been to identify further factors, besides price, that condition the acceptance of the use of desalinated seawater. Finally, a series of measures are proposed to encourage the use of desalinated seawater for irrigation based on the identified profiles. The insights gained from this study could be useful for other regions where the construction of desalination plants has been planned as a measure to increase the availability of irrigation water.

ACS Style

José A. Aznar-Sánchez; Luis J. Belmonte-Ureña; Juan F. Velasco-Muñoz; Diego L. Valera. Farmers’ profiles and behaviours toward desalinated seawater for irrigation: Insights from South-east Spain. Journal of Cleaner Production 2021, 296, 126568 .

AMA Style

José A. Aznar-Sánchez, Luis J. Belmonte-Ureña, Juan F. Velasco-Muñoz, Diego L. Valera. Farmers’ profiles and behaviours toward desalinated seawater for irrigation: Insights from South-east Spain. Journal of Cleaner Production. 2021; 296 ():126568.

Chicago/Turabian Style

José A. Aznar-Sánchez; Luis J. Belmonte-Ureña; Juan F. Velasco-Muñoz; Diego L. Valera. 2021. "Farmers’ profiles and behaviours toward desalinated seawater for irrigation: Insights from South-east Spain." Journal of Cleaner Production 296, no. : 126568.

Journal article
Published: 07 February 2020 in Biosystems Engineering
Reads 0
Downloads 0

This study characterised the geometric and aerodynamic parameters of 35 insect-proof screens with different weft and warp threads, with porosities ranging from 0.237 to 0.556 m2 m−2. The geometric parameters were assessed by analysing digital images, and the aerodynamic parameters were determined using tests in a low-speed wind tunnel. Using the experimental measurements, four different models were developed and validated to estimate the aerodynamic parameters of an insect-proof screen from two or more of their geometric parameters: (i) to estimate the pressure drop coefficient Fφ based on the thread diameter Reynolds number (Red) and screen porosity φ [m2 m−2] Fφ = (0.4810002 + 11.5331/Red) × ((1 − φ2)/φ2) (R2 = 93.9% with a p-value = 0.000); (ii) estimating Fφ based on the screen thickness Reynolds number (Ret) and screen porosity φ [m2 m−2] Fφ = (0.475502 + 26.2114/Ret) × ((1 − φ2)/φ2) (R2 = 92.1% with a p-value = 0.000); (iii) estimating screen permeability Kp = Dh2φ3/(2.0679 (1 − φ)2) + 3.8362 × 10−10 (R2 = 56.3%/56.2% with a p-value <0.05) as a function of thread diameter Dh [m] and porosity φ [m2 m−2]; (iv) estimating the inertial factor Y = 0.0571195 + 0.135966· Dh/Di (R2 = 58.1% with a p-value = 0.0000) as a function of thread diameter Dh [m] and the inner pore diameter Di [m]. These models gave improved accuracy compared with the previous models described in the literature. Models for aerodynamic parameters of the insect-proof screens Kp and Y based in their geometric characteristics are very important to simulate the effects of insect screens in ventilation studies using computational fluid dynamic (CFD) studies.

ACS Style

A. López-Martínez; F.D. Molina-Aiz; D.L. Valera; K.E. Espinoza-Ramos. Models for characterising the aerodynamics of insect-proof screens from their geometric parameters. Biosystems Engineering 2020, 192, 42 -55.

AMA Style

A. López-Martínez, F.D. Molina-Aiz, D.L. Valera, K.E. Espinoza-Ramos. Models for characterising the aerodynamics of insect-proof screens from their geometric parameters. Biosystems Engineering. 2020; 192 ():42-55.

Chicago/Turabian Style

A. López-Martínez; F.D. Molina-Aiz; D.L. Valera; K.E. Espinoza-Ramos. 2020. "Models for characterising the aerodynamics of insect-proof screens from their geometric parameters." Biosystems Engineering 192, no. : 42-55.

Journal article
Published: 05 February 2020 in Agronomy
Reads 0
Downloads 0

This work analyzes the influence of whitening a greenhouse roof on the microclimate and yield of a tomato crop. In the west sectors of two multi-span greenhouses, a whitening concentration of 0.250 kg L−1 was used as a control. In an autumn–winter cycle, a lower (0.125 kg L−1) and an increased (0.500 kg L−1) concentration were used in the east sectors of greenhouses 1 and 2. In a spring–summer cycle, the whitening concentrations in the east were varied depending on outside temperature. The effect of whitening on photosynthetic activity, production, plants’ morphological parameters, and the quality of the fruits were also analyzed. To evaluate the effect on microclimate, solar and photosynthetically active (PAR) radiations, air and soil temperatures, and heat flux in the soil were measured in greenhouse 1. Results show that excessive whitening leads to reductions of inside PAR radiation that decreases photosynthesis and crop yield. A whitening concentration of 0.500 kg L−1 is proposed at the beginning of the autumn–winter crop cycle, washing the cover when inside temperature drops to 35 °C. At the end of the spring–summer cycle, a concentration of 0.125 kg L−1 is recommended when inside temperature increases to 35 °C.

ACS Style

María De Los Ángeles Moreno-Teruel; Diego Valera; Francisco Domingo Molina-Aiz; Alejandro López-Martínez; Araceli Peña; Patricia Marín; Audberto Reyes-Rosas. Effects of Cover Whitening Concentrations on the Microclimate and on the Development and Yield of Tomato (Lycopersicon esculentum Mill.) Inside Mediterranean Greenhouses. Agronomy 2020, 10, 237 .

AMA Style

María De Los Ángeles Moreno-Teruel, Diego Valera, Francisco Domingo Molina-Aiz, Alejandro López-Martínez, Araceli Peña, Patricia Marín, Audberto Reyes-Rosas. Effects of Cover Whitening Concentrations on the Microclimate and on the Development and Yield of Tomato (Lycopersicon esculentum Mill.) Inside Mediterranean Greenhouses. Agronomy. 2020; 10 (2):237.

Chicago/Turabian Style

María De Los Ángeles Moreno-Teruel; Diego Valera; Francisco Domingo Molina-Aiz; Alejandro López-Martínez; Araceli Peña; Patricia Marín; Audberto Reyes-Rosas. 2020. "Effects of Cover Whitening Concentrations on the Microclimate and on the Development and Yield of Tomato (Lycopersicon esculentum Mill.) Inside Mediterranean Greenhouses." Agronomy 10, no. 2: 237.

Evaluation study
Published: 25 November 2019 in International Journal of Environmental Research and Public Health
Reads 0
Downloads 0

This study investigates the temperature reduction capacity and water consumption of a fan-pad system installed in a greenhouse located in the coastal regions of Almería. The suitability of this system for coastal zones with high environmental humidity during the summer is analyzed. Historical temperature and relative humidity series are studied, obtaining the thermal difference and maximum, medium, and minimum monthly water consumption of the pads based on the operation data of the pads. Despite the high relative humidity of the air in the hottest hours of the day, a decrease of 5.92 °C in the mean temperature and a water consumption of 13.55 l/h per square meter of an evaporative cooling pad are obtained in the month of August. Additionally, the operation of a cellulose evaporative cooling pad installed for 3 years in a greenhouse is analyzed in a wind tunnel and compared with that of a new pad of the same model. Over time and with low maintenance, the porosity of the pad decreases due to salt incrustation. The salt incrustation makes airflow more difficult in the pad, increasing the pressure drop by 170.04%; however, the air saturation efficiency of the pad increases by 6.6% due to the greater contact time between the air and the water.

ACS Style

Antonio Franco-Salas; Araceli Peña-Fernández; Diego Luis Valera-Martínez. Refrigeration Capacity and Effect of Ageing on the Operation of Cellulose Evaporative Cooling Pads, by Wind Tunnel Analysis. International Journal of Environmental Research and Public Health 2019, 16, 4690 .

AMA Style

Antonio Franco-Salas, Araceli Peña-Fernández, Diego Luis Valera-Martínez. Refrigeration Capacity and Effect of Ageing on the Operation of Cellulose Evaporative Cooling Pads, by Wind Tunnel Analysis. International Journal of Environmental Research and Public Health. 2019; 16 (23):4690.

Chicago/Turabian Style

Antonio Franco-Salas; Araceli Peña-Fernández; Diego Luis Valera-Martínez. 2019. "Refrigeration Capacity and Effect of Ageing on the Operation of Cellulose Evaporative Cooling Pads, by Wind Tunnel Analysis." International Journal of Environmental Research and Public Health 16, no. 23: 4690.

Journal article
Published: 10 November 2019 in Agronomy
Reads 0
Downloads 0

The present work analyses the natural ventilation of a multi-span greenhouse with one roof vent and two side vents by means of sonic anemometry. Opening the roof vent to windward, one side vent to leeward, and the other side vents to windward (this last vent obstructed by another greenhouse), causes opposing thermal GT (m3 s−1) and wind effects Gw (m3 s−1), as outside air entering the greenhouse through the roof vent circulates downward, contrary to natural convection due to the thermal effect. In our case, the ventilation rate RM (h−1) in a naturally ventilated greenhouse fits a second order polynomial with wind velocity uo (RM = 0.37 uo2 + 0.03 uo + 0.75; R2 = 0.99). The opposing wind and thermal effects mean that ventilation models based on Bernoulli’s equation must be modified in order to add or subtract their effects accordingly—Model 1, in which the flow is driven by the sum of two independent pressure fields GM1=GT2±Gw2, or Model 2, in which the flow is driven by the sum of two independent fluxes GM2=GT±Gw. A linear relationship has been obtained, which allows us to estimate the discharge coefficient of the side vents (CdVS) and roof vent (CdWR) as a function of uo [CdVS = 0.028 uo + 0.028 (R2 = 0.92); CdWR = 0.036 uo + 0.040 (R2 = 0.96)]. The wind effect coefficient Cw was determined by applying models M1 and M2 proved not to remain constant for the different experiments, but varied according to the ratio uo/∆Tio0.5 or δ [CwM1 = exp(-2.693 + 1.160/δ) (R2 = 0.94); CwM2 = exp(−2.128 + 1.264/δ) (R2 = 0.98)].

ACS Style

López- Martínez; Francisco D. Molina-Aiz; Valera- Martínez; Araceli Peña-Fernández; Karlos Espinoza. Application of Semi-Empirical Ventilation Models in A Mediterranean Greenhouse with Opposing Thermal and Wind Effects. Use of Non-Constant Cd (Pressure Drop Coefficient Through the Vents) and Cw (Wind Effect Coefficient). Agronomy 2019, 9, 736 .

AMA Style

López- Martínez, Francisco D. Molina-Aiz, Valera- Martínez, Araceli Peña-Fernández, Karlos Espinoza. Application of Semi-Empirical Ventilation Models in A Mediterranean Greenhouse with Opposing Thermal and Wind Effects. Use of Non-Constant Cd (Pressure Drop Coefficient Through the Vents) and Cw (Wind Effect Coefficient). Agronomy. 2019; 9 (11):736.

Chicago/Turabian Style

López- Martínez; Francisco D. Molina-Aiz; Valera- Martínez; Araceli Peña-Fernández; Karlos Espinoza. 2019. "Application of Semi-Empirical Ventilation Models in A Mediterranean Greenhouse with Opposing Thermal and Wind Effects. Use of Non-Constant Cd (Pressure Drop Coefficient Through the Vents) and Cw (Wind Effect Coefficient)." Agronomy 9, no. 11: 736.

Journal article
Published: 24 October 2019 in International Journal of Environmental Research and Public Health
Reads 0
Downloads 0

Globally, current food consumption and trade are placing unprecedented demand on agricultural systems and increasing pressure on natural resources, requiring tradeoffs between food security and environmental impacts especially given the tension between market-driven agriculture and agro-ecological goals. In order to illustrate the wicked social, economic and environmental challenges and processes to find transformative solutions, we focus on the largest concentration of greenhouses in the world located in the semi-arid coastal plain of South-east Spain. Almería family farming, predominantly cooperative, greenhouse intensive production, commenced after the 1960s and has resulted in very significant social and economic benefits for the region, while also having important negative environmental and biodiversity impacts, as well as creating new social challenges. The system currently finds itself in a crisis of diminishing economic benefits and increasing environmental and social dilemmas. Here, we present the outcomes of multi-actor, transdisciplinary research to review and provide collective insights for solutions-oriented research on the sustainability of Almeria’s agricultural sector. The multi-actor, transdisciplinary process implemented collectively, and supported by scientific literature, identified six fundamental challenges to transitioning to an agricultural model that aims to ameliorate risks and avoid a systemic collapse, whilst balancing a concern for profitability with sustainability: (1) Governance based on a culture of shared responsibility for sustainability, (2) Sustainable and efficient use of water, (3) Biodiversity conservation, (4) Implementing a circular economy plan, (5) Technology and knowledge transfer, and (6) Image and identity. We conclude that the multi-actor transdisciplinary approach successfully facilitated the creation of a culture of shared responsibility among public, private, academic, and civil society actors. Notwithstanding plural values, challenges and solutions identified by consensus point to a nascent acknowledgement of the strategic necessity to locate agricultural economic activity within social and environmental spheres.This paper demonstrates the need to establish transdisciplinary multi-actor work-schemes to continue collaboration and research for the transition to an agro-ecological model as a means to remain competitive and to create value.

ACS Style

Antonio J. Castro; María D. López-Rodríguez; Cynthia Giagnocavo; Miguel Gimenez; Leticia Céspedes; Abel La Calle; Marisa Gallardo; Pablo Pumares; Javier Cabello; Estefanía Rodríguez; David Uclés; Salvador Parra; Jesús Casas; Francisco Rodríguez; Juan Sebastián Fernández-Prados; Daniela Alba-Patiño; Mónica Expósito-Granados; Beatriz E. Murillo-López; Lina M. Vasquez; Diego L. Valera. Six Collective Challenges for Sustainability of Almería Greenhouse Horticulture. International Journal of Environmental Research and Public Health 2019, 16, 4097 .

AMA Style

Antonio J. Castro, María D. López-Rodríguez, Cynthia Giagnocavo, Miguel Gimenez, Leticia Céspedes, Abel La Calle, Marisa Gallardo, Pablo Pumares, Javier Cabello, Estefanía Rodríguez, David Uclés, Salvador Parra, Jesús Casas, Francisco Rodríguez, Juan Sebastián Fernández-Prados, Daniela Alba-Patiño, Mónica Expósito-Granados, Beatriz E. Murillo-López, Lina M. Vasquez, Diego L. Valera. Six Collective Challenges for Sustainability of Almería Greenhouse Horticulture. International Journal of Environmental Research and Public Health. 2019; 16 (21):4097.

Chicago/Turabian Style

Antonio J. Castro; María D. López-Rodríguez; Cynthia Giagnocavo; Miguel Gimenez; Leticia Céspedes; Abel La Calle; Marisa Gallardo; Pablo Pumares; Javier Cabello; Estefanía Rodríguez; David Uclés; Salvador Parra; Jesús Casas; Francisco Rodríguez; Juan Sebastián Fernández-Prados; Daniela Alba-Patiño; Mónica Expósito-Granados; Beatriz E. Murillo-López; Lina M. Vasquez; Diego L. Valera. 2019. "Six Collective Challenges for Sustainability of Almería Greenhouse Horticulture." International Journal of Environmental Research and Public Health 16, no. 21: 4097.

Journal article
Published: 18 March 2019 in International Journal of Environmental Research and Public Health
Reads 0
Downloads 0

The present work analyses the traditional method of applying whitening products on Mediterranean greenhouses. Four commercial whitening products (agricultural solar protectors, ASPs), applied at four doses, were compared with a non-whitened cover. The traditional product “Blanco de España” with 99% calcium carbonate (CaCO3) and other three products with 97% CaCO3 that incorporate adhesives were tested. The use of adhesives in ASP did not influence the effect of the different products on the inside temperature, and at the same dose all four products show a similar behaviour. The findings support the maximum dose recommended by other authors of 0.50 kg L−1 (50/100), above which the transmissivity of the greenhouse cover decreases by over 50%. The effect of ASP on the transmissivity of the cover depends principally on the dose applied, but also on the climatic conditions (solar radiation, cloud cover, etc.) and on the time of year (solar elevation). The habitual use of a constant dose throughout the year does not seem to be the most adequate. Recommended doses should vary according to the time of year and the desired degree of transmissivity reduction. The adhesive components are shown to provide a high degree of protection against heavy rain. The study recommends a standardised method of ASP application, establishing a method that allows the grower to verify the concentration of the product that will remain on the greenhouse cover.

ACS Style

Alejandro López-Martínez; Diego Luis Valera-Martínez; Francisco Domingo Molina-Aiz; María De Los Ángeles Moreno-Teruel; Araceli Peña-Fernández; Karlos Emmanuel Espinoza-Ramos. Analysis of the Effect of Concentrations of Four Whitening Products in Cover Transmissivity of Mediterranean Greenhouses. International Journal of Environmental Research and Public Health 2019, 16, 958 .

AMA Style

Alejandro López-Martínez, Diego Luis Valera-Martínez, Francisco Domingo Molina-Aiz, María De Los Ángeles Moreno-Teruel, Araceli Peña-Fernández, Karlos Emmanuel Espinoza-Ramos. Analysis of the Effect of Concentrations of Four Whitening Products in Cover Transmissivity of Mediterranean Greenhouses. International Journal of Environmental Research and Public Health. 2019; 16 (6):958.

Chicago/Turabian Style

Alejandro López-Martínez; Diego Luis Valera-Martínez; Francisco Domingo Molina-Aiz; María De Los Ángeles Moreno-Teruel; Araceli Peña-Fernández; Karlos Emmanuel Espinoza-Ramos. 2019. "Analysis of the Effect of Concentrations of Four Whitening Products in Cover Transmissivity of Mediterranean Greenhouses." International Journal of Environmental Research and Public Health 16, no. 6: 958.

Journal article
Published: 12 March 2019 in International Journal of Environmental Research and Public Health
Reads 0
Downloads 0

In the Campo de Níjar (southeast Spain), an intensive horticulture model under plastic has been developed based on the use of groundwater. For many years, aquifers have been overexploited, almost generating an environmental collapse. The construction of a desalination plant was planned to improve this situation and to achieve sustainable aquifer management. However, the aquifer is still being overexploited, since farmers scarcely use desalinated seawater for irrigation. In this paper, farmers irrigating with desalinated seawater are characterized, since they contribute to aquifer sustainability. The study aimed to identify the variables which condition the use of this water resource, as well as the kinds of incentives that encourage this option. For this purpose, a survey was undertaken within a sample of 110 farmers. A cluster analysis and a binary logistic regression were employed. The results from the cluster analysis allowed the characterization of farmers who use desalinated seawater for irrigation. Furthermore, the regression model showed the variables that determine a more intensive use of this irrigation source, such as crop diversification, availability of different water resources and the conductivity of aquifer water available for irrigation. The incentives promoting the use of desalinated seawater for irrigation that most encourage farmers are the implementation of tax relief, price reductions and the obligation to install rainwater collection systems.

ACS Style

José A. Aznar-Sánchez; Luis J. Belmonte-Ureña; Juan F. Velasco-Muñoz; Diego L. Valera. Aquifer Sustainability and the Use of Desalinated Seawater for Greenhouse Irrigation in the Campo de Níjar, Southeast Spain. International Journal of Environmental Research and Public Health 2019, 16, 898 .

AMA Style

José A. Aznar-Sánchez, Luis J. Belmonte-Ureña, Juan F. Velasco-Muñoz, Diego L. Valera. Aquifer Sustainability and the Use of Desalinated Seawater for Greenhouse Irrigation in the Campo de Níjar, Southeast Spain. International Journal of Environmental Research and Public Health. 2019; 16 (5):898.

Chicago/Turabian Style

José A. Aznar-Sánchez; Luis J. Belmonte-Ureña; Juan F. Velasco-Muñoz; Diego L. Valera. 2019. "Aquifer Sustainability and the Use of Desalinated Seawater for Greenhouse Irrigation in the Campo de Níjar, Southeast Spain." International Journal of Environmental Research and Public Health 16, no. 5: 898.

Journal article
Published: 08 January 2019 in Spanish Journal of Agricultural Research
Reads 0
Downloads 0

The present work examines the variations in the aerodynamic characteristics of four insect-proof screens by means of wind tunnel tests and digital image processing. The tested insect-proof screens were examined in three different conditions: (i) in their new, unused state; (ii) under conditions of accumulated dust and dirt after a period of 3 to 4 years of use; and (iii) under clean conditions after a period of 3 to 4 years of use and a cleaning treatment with high-pressure water. The deterioration of the screens caused the mesh to become less tense, therefore increasing its thickness and improving its aerodynamic behaviour despite a slight increase of the thread diameter and a subsequent decrease of the 2-dimensional porosity. The pressure drop coefficient, Fφ, of the used but clean screens was 1.5% to 8.8% lower (for u=1.0 m/s) than that of the new ones, thus increasing the discharge coefficient, Cd,φ, by between 0.8% and 4.8% as a result of the presence of the screens. On the other hand, comparison of the used screens in their clean and unclean states showed that the accumulation of dirt has a major bearing on their aerodynamic characteristics: Fφ increased by between 16.5% and 61.2% (for u=1.0 m/s) for the unclean screens, resulting in a Cd,φ reduction of between 7.5% and 21.3% and therefore a lower natural ventilation capacity of the greenhouse. A regular cleaning treatment of the insect-proof screens is a simple measure that improves the natural ventilation capacity of the greenhouse.

ACS Style

Alejandro López; Francisco Domingo Molina-Aiz; Diego L. Valera; Araceli Peña; Karlos Espinoza. Effect of material ageing and dirt on the behaviour of greenhouse insect-proof screens. Spanish Journal of Agricultural Research 2019, 16, e0205 .

AMA Style

Alejandro López, Francisco Domingo Molina-Aiz, Diego L. Valera, Araceli Peña, Karlos Espinoza. Effect of material ageing and dirt on the behaviour of greenhouse insect-proof screens. Spanish Journal of Agricultural Research. 2019; 16 (4):e0205.

Chicago/Turabian Style

Alejandro López; Francisco Domingo Molina-Aiz; Diego L. Valera; Araceli Peña; Karlos Espinoza. 2019. "Effect of material ageing and dirt on the behaviour of greenhouse insect-proof screens." Spanish Journal of Agricultural Research 16, no. 4: e0205.

Research article
Published: 26 July 2018 in Journal of Agricultural and Food Chemistry
Reads 0
Downloads 0

This study describes the approach of 1H NMR metabolomic profiling for the differentiation of zucchini produced under different conditions of water irrigation (desalinated seawater −0.397 dS/m, 0.52 €/m3 vs groundwater −2.36 dS/m, 0.29 €/m3) and ventilation (surface area of the vent openings/greenhouse area was 15.0% for one sector and 9.8% for the other). Overall, 72 extracts of zucchini (Cucubirta pepo L. cv Victoria) under four different conditions were regularly analyzed during the spring-summer cycle from April to July 2017. We have found that zucchini plants irrigated with desalinated seawater increased the zucchini production yield, presented fruits with higher concentration of glucose, fructose, and vitamin B3, and displayed an increased antioxidant activity. On the contrary, plant groundwater irrigation produced the increment of sucrose level that could rise the sweetness perception of the fruits. Finally, the ventilation variable produced a higher concentration of trigonelline, histidine, and phenylalanine but only on those zucchinis irrigated with groundwater.

ACS Style

Ana Cristina Abreu; Luis Manuel Aguilera-Sáez; Araceli Peña; Mar García-Valverde; Patricia Marín; Diego L. Valera; Ignacio Fernández. NMR-Based Metabolomics Approach To Study the Influence of Different Conditions of Water Irrigation and Greenhouse Ventilation on Zucchini Crops. Journal of Agricultural and Food Chemistry 2018, 66, 8422 -8432.

AMA Style

Ana Cristina Abreu, Luis Manuel Aguilera-Sáez, Araceli Peña, Mar García-Valverde, Patricia Marín, Diego L. Valera, Ignacio Fernández. NMR-Based Metabolomics Approach To Study the Influence of Different Conditions of Water Irrigation and Greenhouse Ventilation on Zucchini Crops. Journal of Agricultural and Food Chemistry. 2018; 66 (31):8422-8432.

Chicago/Turabian Style

Ana Cristina Abreu; Luis Manuel Aguilera-Sáez; Araceli Peña; Mar García-Valverde; Patricia Marín; Diego L. Valera; Ignacio Fernández. 2018. "NMR-Based Metabolomics Approach To Study the Influence of Different Conditions of Water Irrigation and Greenhouse Ventilation on Zucchini Crops." Journal of Agricultural and Food Chemistry 66, no. 31: 8422-8432.

Agrometeorology
Published: 01 December 2017 in Scientia Agricola
Reads 0
Downloads 0

The present work analyzes the effectiveness of windbreaks against wind erosion through the study of streamline patterns and turbulent flow by means of sonic anemometry and sediment traps. To this end, windbreaks composed of plastic meshes (7.5 m long and 0.7 m tall) were used. Windbreaks are a good means to reduce wind erosion, as they produce a positive effect on the characteristics of air currents that are related to wind erosion processes. Due to their ease of installation and dismantling, plastic meshes are widely used in areas where they are not required permanently. In our study, the use of a mesh of 13 × 30 threads cm−2 and 39 % porosity resulted in an average reduction of 85 % in face velocity at a height of 0.4 m and a distance of 1 m from the windbreak. The turbulence intensity i increased behind the windbreak because the reduction of mean of air speed on the leeside caused by the flow of air through the windbreak. Fluctuation levels, however, remained stable. The mean values of turbulence kinetic energy k decreased by 65 % to 86 % at a distance of 1 m from the windbreak and at a height of 0.4 m. The windbreak reduces erosion and sediment transportation 2 m downwind (2.9 times the windbreak height). Nevertheless, sediment transportation was not reduced at a height of 1.0 m and the effect of the windbreak was not observed at a distance of 6 m downwind (8.6 m times the windbreak height).

ACS Style

Alejandro López; Diego Luis Valera; Francisco Domingo Molina-Aiz; Francisco Javier Lozano; Carlos Asensio. Sonic anemometry and sediment traps to evaluate the effectiveness of windbreaks in preventing wind erosion. Scientia Agricola 2017, 74, 425 -435.

AMA Style

Alejandro López, Diego Luis Valera, Francisco Domingo Molina-Aiz, Francisco Javier Lozano, Carlos Asensio. Sonic anemometry and sediment traps to evaluate the effectiveness of windbreaks in preventing wind erosion. Scientia Agricola. 2017; 74 (6):425-435.

Chicago/Turabian Style

Alejandro López; Diego Luis Valera; Francisco Domingo Molina-Aiz; Francisco Javier Lozano; Carlos Asensio. 2017. "Sonic anemometry and sediment traps to evaluate the effectiveness of windbreaks in preventing wind erosion." Scientia Agricola 74, no. 6: 425-435.

Journal article
Published: 01 December 2017 in Biosystems Engineering
Reads 0
Downloads 0
ACS Style

Karlos Espinoza; Alejandro López; Diego L. Valera; Francisco D. Molina-Aiz; José A. Torres; Araceli Peña. Effects of ventilator configuration on the flow pattern of a naturally-ventilated three-span Mediterranean greenhouse. Biosystems Engineering 2017, 164, 13 -30.

AMA Style

Karlos Espinoza, Alejandro López, Diego L. Valera, Francisco D. Molina-Aiz, José A. Torres, Araceli Peña. Effects of ventilator configuration on the flow pattern of a naturally-ventilated three-span Mediterranean greenhouse. Biosystems Engineering. 2017; 164 ():13-30.

Chicago/Turabian Style

Karlos Espinoza; Alejandro López; Diego L. Valera; Francisco D. Molina-Aiz; José A. Torres; Araceli Peña. 2017. "Effects of ventilator configuration on the flow pattern of a naturally-ventilated three-span Mediterranean greenhouse." Biosystems Engineering 164, no. : 13-30.

Journal article
Published: 01 November 2017 in Computers and Electronics in Agriculture
Reads 0
Downloads 0
ACS Style

Audberto Reyes-Rosas; Francisco Domingo Molina-Aiz; Diego L. Valera; Alejandro López; Sasirot Khamkure. Development of a single energy balance model for prediction of temperatures inside a naturally ventilated greenhouse with polypropylene soil mulch. Computers and Electronics in Agriculture 2017, 142, 9 -28.

AMA Style

Audberto Reyes-Rosas, Francisco Domingo Molina-Aiz, Diego L. Valera, Alejandro López, Sasirot Khamkure. Development of a single energy balance model for prediction of temperatures inside a naturally ventilated greenhouse with polypropylene soil mulch. Computers and Electronics in Agriculture. 2017; 142 ():9-28.

Chicago/Turabian Style

Audberto Reyes-Rosas; Francisco Domingo Molina-Aiz; Diego L. Valera; Alejandro López; Sasirot Khamkure. 2017. "Development of a single energy balance model for prediction of temperatures inside a naturally ventilated greenhouse with polypropylene soil mulch." Computers and Electronics in Agriculture 142, no. : 9-28.

Journal article
Published: 08 June 2017 in Water
Reads 0
Downloads 0

In the context of increasing demand for irrigation water—but, at the same time, with the constraints in the supply from traditional resources—desalinated seawater has been recognized as one of the alternative sources of water to increase the supply for agricultural irrigation. However, its use among farmers has not yet started to expand. Policy makers need to understand what is causing the low acceptance levels of farmers, and how their attitudes could be improved. This is the first study that has conducted an analysis of farmers’ perceptions and acceptance of the use of desalinated seawater for irrigation. The study is based on collected data from a survey completed by farmers in southeastern Spain who do not use desalinated seawater. The main results indicate that desalinated seawater as a water supply source has the lowest acceptance level for farmers. Barriers for its use are price, the need for additional fertilization, and the perception that it would negatively affect the yield and crop quality. The farmers’ general level of knowledge about the impact of using desalinated seawater in agriculture is extremely low. Furthermore, farmers consider it a priority that their startup investment should be subsidized and that water prices should be reduced. Based on the study findings, this paper makes recommendations for the decision-making process in order to improve farmers’ acceptance levels.

ACS Style

José A. Aznar-Sánchez; Luis J. Belmonte-Ureña; Diego L. Valera. Perceptions and Acceptance of Desalinated Seawater for Irrigation: A Case Study in the Níjar District (Southeast Spain). Water 2017, 9, 408 .

AMA Style

José A. Aznar-Sánchez, Luis J. Belmonte-Ureña, Diego L. Valera. Perceptions and Acceptance of Desalinated Seawater for Irrigation: A Case Study in the Níjar District (Southeast Spain). Water. 2017; 9 (6):408.

Chicago/Turabian Style

José A. Aznar-Sánchez; Luis J. Belmonte-Ureña; Diego L. Valera. 2017. "Perceptions and Acceptance of Desalinated Seawater for Irrigation: A Case Study in the Níjar District (Southeast Spain)." Water 9, no. 6: 408.

Journal article
Published: 12 September 2016 in Sustainability
Reads 0
Downloads 0

Over 1000 hectares of citrus fruits crops are grown in the Bajo Andarax district in Almeria (Spain). The withdrawal of EU subsidies for conventional production led to a drastic loss of economic profitability of the holdings and, consequently, the abandonment of most of the conventionally managed farms of the district. In this context, a restructuring of the citrus sector from conventional to organic farming was implemented as a strategic measure to achieve the long-term sustainable development of the holdings. This study examines the citrus sector of the district and performs a comprehensive evaluation of the economic sustainability of this shift from conventional to organic production. In addition, the impact of the restructuring of the sector on the social sustainability both at the farm level and at the municipality level is studied. The results of the study are of interest to other agricultural areas of compromised profitability in which a shift towards organic production can represent a viable alternative for the economic and social sustainability of the holdings.

ACS Style

Juan Torres; Diego L. Valera; Luis J. Belmonte; Carlos Herrero-Sánchez. Economic and Social Sustainability through Organic Agriculture: Study of the Restructuring of the Citrus Sector in the “Bajo Andarax” District (Spain). Sustainability 2016, 8, 918 .

AMA Style

Juan Torres, Diego L. Valera, Luis J. Belmonte, Carlos Herrero-Sánchez. Economic and Social Sustainability through Organic Agriculture: Study of the Restructuring of the Citrus Sector in the “Bajo Andarax” District (Spain). Sustainability. 2016; 8 (9):918.

Chicago/Turabian Style

Juan Torres; Diego L. Valera; Luis J. Belmonte; Carlos Herrero-Sánchez. 2016. "Economic and Social Sustainability through Organic Agriculture: Study of the Restructuring of the Citrus Sector in the “Bajo Andarax” District (Spain)." Sustainability 8, no. 9: 918.

Journal article
Published: 01 September 2016 in Computers and Electronics in Agriculture
Reads 0
Downloads 0

Display Omitted Image processing coupled with artificial neural network were used in a IPM system.Fed-forward neural networks were used to identify two pest species in greenhouses.Proposed whitefly and thrip identification method had a high precision, 0.96 and 0.92.Common sticky traps were used in a semi-automatic early pest detection system. Integrated Pest Management (IPM) lies at the core of the current efforts to reduce the use of deleterious chemicals in greenhouse agriculture. IPM strategies rely on the early detection and continuous monitoring of pest populations, a critical task that is not only time-consuming but also highly dependent on human judgement and therefore prone to error. In this study, we propose a novel approach for the detection and monitoring of adult-stage whitefly (Bemisia tabaci) and thrip (Frankliniella occidentalis) in greenhouses based on the combination of an image-processing algorithm and artificial neural networks. Digital images of sticky traps were obtained via an image-acquisition system. Detection of the objects in the images, segmentation, and morphological and color property estimation was performed by an image-processing algorithm for each of the detected objects. Finally, classification was achieved by means of a feed-forward multi-layer artificial neural network. The proposed whitefly identification algorithm achieved high precision (0.96), recall (0.95) and F-measure (0.95) values, whereas the thrip identification algorithm obtained similar precision (0.92), recall (0.96) and F-measure (0.94) values.

ACS Style

Karlos Espinoza; Diego L. Valera; José A. Torres; Alejandro López; Francisco Domingo Molina-Aiz. Combination of image processing and artificial neural networks as a novel approach for the identification of Bemisia tabaci and Frankliniella occidentalis on sticky traps in greenhouse agriculture. Computers and Electronics in Agriculture 2016, 127, 495 -505.

AMA Style

Karlos Espinoza, Diego L. Valera, José A. Torres, Alejandro López, Francisco Domingo Molina-Aiz. Combination of image processing and artificial neural networks as a novel approach for the identification of Bemisia tabaci and Frankliniella occidentalis on sticky traps in greenhouse agriculture. Computers and Electronics in Agriculture. 2016; 127 ():495-505.

Chicago/Turabian Style

Karlos Espinoza; Diego L. Valera; José A. Torres; Alejandro López; Francisco Domingo Molina-Aiz. 2016. "Combination of image processing and artificial neural networks as a novel approach for the identification of Bemisia tabaci and Frankliniella occidentalis on sticky traps in greenhouse agriculture." Computers and Electronics in Agriculture 127, no. : 495-505.

Journal article
Published: 24 August 2016 in Ingeniería e Investigación
Reads 0
Downloads 0

The aim of the study is to evaluate the effect of the height of the greenhouse on climatic conditions generated on a mint crop (Mentha spicata). The tests were conducted in the town of Carmen de Viboral, 40 minutes away from the city of Medellin (6º 05’ 09” N and 75º 20’ 19” W, 2150 m.a.s.l.). Three greenhouses with the same dimensions were used, changing only the gutter height in 2 m, 2,5 m and 3 m respectively. Temperature and relative humidity measurements were taken every 30 minutes for 3 years, time during which crop production was assessed. Statistical analyses were performed to determine climatic variations caused by the difference in height between the greenhouses, and to determine differences in production levels. The results indicate that, under the study conditions, the greenhouse height directly affects the weather conditions and the mint crop yields.

ACS Style

Nelson Bustamante Valencia; John Fabio Acuña Caita; Diego Luis Valera Martínez. Effect of the height of the greenhouse on the plant - climate relationship as a development parameter in mint (Mentha Spicata) crops in Colombia. Ingeniería e Investigación 2016, 36, 6 .

AMA Style

Nelson Bustamante Valencia, John Fabio Acuña Caita, Diego Luis Valera Martínez. Effect of the height of the greenhouse on the plant - climate relationship as a development parameter in mint (Mentha Spicata) crops in Colombia. Ingeniería e Investigación. 2016; 36 (2):6.

Chicago/Turabian Style

Nelson Bustamante Valencia; John Fabio Acuña Caita; Diego Luis Valera Martínez. 2016. "Effect of the height of the greenhouse on the plant - climate relationship as a development parameter in mint (Mentha Spicata) crops in Colombia." Ingeniería e Investigación 36, no. 2: 6.

Journal article
Published: 12 May 2016 in Sensors
Reads 0
Downloads 0

The present work studies the effect of three insect-proof screens with different geometrical and aerodynamic characteristics on the air velocity and temperature inside a Mediterranean multi-span greenhouse with three roof vents and without crops, divided into two independent sectors. First, the insect-proof screens were characterised geometrically by analysing digital images and testing in a low velocity wind tunnel. The wind tunnel tests gave screen discharge coefficient values of Cd,φ of 0.207 for screen 1 (10 × 20 threads·cm−2; porosity φ = 35.0%), 0.151 for screen 2 (13 × 30 threads·cm−2; φ = 26.3%) and 0.325 for screen 3 (10 × 20 threads·cm−2; porosity φ = 36.0%), at an air velocity of 0.25 m·s−1. Secondly, when screens were installed in the greenhouse, we observed a statistical proportionality between the discharge coefficient at the openings and the air velocity ui measured in the centre of the greenhouse, ui = 0.856 Cd + 0.062 (R2 = 0.68 and p-value = 0.012). The inside-outside temperature difference ΔTio diminishes when the inside velocity increases following the statistically significant relationship ΔTio = (−135.85 + 57.88/ui)0.5 (R2 = 0.85 and p-value = 0.0011). Different thread diameters and tension affects the screen thickness, and means that similar porosities may well be associated with very different aerodynamic characteristics. Screens must be characterised by a theoretical function Cd,φ = [(2eμ/Kpρ)·(1/us) + (2eY/Kp0.5)]−0.5 that relates the discharge coefficient of the screen Cd,φ with the air velocity us. This relationship depends on the three parameters that define the aerodynamic behaviour of porous medium: permeability Kp, inertial factor Y and screen thickness e (and on air temperature that determine its density ρ and viscosity μ). However, for a determined temperature of air, the pressure drop-velocity relationship can be characterised only with two parameters: ΔP = aus2 + bus.

ACS Style

Alejandro López; Francisco Domingo Molina-Aiz; Diego L. Valera; Araceli Peña. Wind Tunnel Analysis of the Airflow through Insect-Proof Screens and Comparison of Their Effect When Installed in a Mediterranean Greenhouse. Sensors 2016, 16, 690 .

AMA Style

Alejandro López, Francisco Domingo Molina-Aiz, Diego L. Valera, Araceli Peña. Wind Tunnel Analysis of the Airflow through Insect-Proof Screens and Comparison of Their Effect When Installed in a Mediterranean Greenhouse. Sensors. 2016; 16 (5):690.

Chicago/Turabian Style

Alejandro López; Francisco Domingo Molina-Aiz; Diego L. Valera; Araceli Peña. 2016. "Wind Tunnel Analysis of the Airflow through Insect-Proof Screens and Comparison of Their Effect When Installed in a Mediterranean Greenhouse." Sensors 16, no. 5: 690.

Journal article
Published: 12 August 2015 in Sensors
Reads 0
Downloads 0

Wind tunnels are a key experimental tool for the analysis of airflow parameters in many fields of application. Despite their great potential impact on agricultural research, few contributions have dealt with the development of automatic control systems for wind tunnels in the field of greenhouse technology. The objective of this paper is to present an automatic control system that provides precision and speed of measurement, as well as efficient data processing in low-speed wind tunnel experiments for greenhouse engineering applications. The system is based on an algorithm that identifies the system model and calculates the optimum PI controller. The validation of the system was performed on a cellulose evaporative cooling pad and on insect-proof screens to assess its response to perturbations. The control system provided an accuracy of <0.06 m·s−1 for airflow speed and <0.50 Pa for pressure drop, thus permitting the reproducibility and standardization of the tests. The proposed control system also incorporates a fully-integrated software unit that manages the tests in terms of airflow speed and pressure drop set points.

ACS Style

Karlos Espinoza; Diego L. Valera; José A. Torres; Alejandro López; Francisco D. Molina-Aiz. An Auto-Tuning PI Control System for an Open-Circuit Low-Speed Wind Tunnel Designed for Greenhouse Technology. Sensors 2015, 15, 19723 -19749.

AMA Style

Karlos Espinoza, Diego L. Valera, José A. Torres, Alejandro López, Francisco D. Molina-Aiz. An Auto-Tuning PI Control System for an Open-Circuit Low-Speed Wind Tunnel Designed for Greenhouse Technology. Sensors. 2015; 15 (8):19723-19749.

Chicago/Turabian Style

Karlos Espinoza; Diego L. Valera; José A. Torres; Alejandro López; Francisco D. Molina-Aiz. 2015. "An Auto-Tuning PI Control System for an Open-Circuit Low-Speed Wind Tunnel Designed for Greenhouse Technology." Sensors 15, no. 8: 19723-19749.