A.J. Callejón-Ferre

Greenhouse tomato production with electricity generation by roof-mounted flexible solar panels

The integration of renewable energy sources into greenhouse crop production in southeastern Spain could provide extra income for growers. Wind energy could be captured by small to medium-sized wind turbines, gas could be produced from biomass, and solar energy could be gathered by solar panels. The aim of this study was to examine the effect of flexible solar panels, mounted on top of a greenhouse for electricity production, on yield and fruit quality of tomatoes (Solanum lycopersycum L., cv Daniela). This study was undertaken in a commercial raspa y amagado greenhouse, typical of the Almeria region (Spain). Tomato plantlets were planted at a density of 0.75 plants m-2. The flexible solar panels were mounted on two parts of the roof in different arrangements (T1 and T2), each blacking out 9.8 % of its surface area. A control area (T0 arrangement) was fitted with no panels. No difference was found in terms of total or marketable production under these three arrangements, although fruit mean mass and maximum diameter of T0 were significantly greater than T1 and T2. Fruit in T0 matured earlier with more intense color compared with those in T1 and T2. However, these differences had no effect on price as the tomatoes produced under three conditions fell into the same commercial class (G class; diameter 67-81 mm). Solar panels covering 9.8 % roof area of the greenhouse did not affect yield and price of tomatoes despite of their negative effect on fruit size and color.

Improving the climate safety of workers in Almería-type greenhouses in Spain by predicting the periods when they are most likely to suffer thermal stress

The humidex and wind-chill indices were used to determine the periods in which labourers working in Almería-type greenhouses in southeastern Spain are most likely to suffer conditions able to induce heat and cold stress. Over 500,000 pieces of data for wet and dry bulb temperatures and relative humidity, recorded over a period in excess of five years by a weather station located in an Almería-type greenhouse containing a grass crop, were used in the calculation of these indices. The wind-chill index results showed cold stress never to be a problem, but the humidex index results showed that conditions under which heat stress could develop were common in the warmer months. A clock diagram was produced showing the hours when heat stress is likely to occur in each month of the year. This information could be used to improve the conditions of labourers working in this type of greenhouse; some ways of reducing their exposure to heat stress-inducing conditions are discussed.

Accidents in the greenhouse-construction industry of SE Spain

This work analyses the labour accidents in the greenhouse-construction industry of SE Spain for the period 1999-2007 through a sample of 180 accident reports. The accidents were characterised by studying 5 variables in order to know the day of the week in which the accident occurred, the hour of the day of the accident, type of accident, the region of Spain in which the accident happened, and the resulting injury. The data characterising the accidents were submitted to a descriptive multiple-correspondence analysis. The incidence of accidents in the greenhouse-construction industry presented a high mean value of 15133.7 per 100,000 workers per year. The days with the greatest incidence of accidents were Thursday and Monday, while the period of greatest number of accidents occurred in the first 4h of the workday. No significant correspondence was found between the day of the week, the hour of the day, or any of the other 3 variables studied. The types of accidents with most frequency were: cuts, punctures, contact with hard or rough material, overexertion, and falls from one level to another. The most affected parts of the anatomy were the eyes, thorax, back, sides, lower legs, and feet. The most common types of injury were bone fractures, twists and sprains, distended muscles, contusions, and being crushed. The study calls attention to the high number of accidents at work, which needs to be corrected by fulfilment of safety regulations at work, on the part of the company. Finally, recommendations are made to correct this situation of high number of accidents at work.

Mechanized methods for harvesting residual biomass from Mediterranean fruit tree cultivations.

This study evaluates the technology and work systems used in order to harvest residual biomass from pruning in the specific conditions of Mediterranean fruit orchards (narrow distances between crop-rows). Harvesting has been divided into several types of operations - pruning, biomass alignment between crop tracks, biomass concentration in piles, chipping and bundling - which have been analyzed in five Mediterranean cultivations for three years. Altogether, three types of pruning have been analyzed: Manual, previous mechanical followed by manual, and fully mechanical; Two types of alignment: Manual and mechanical; Three concentration systems: Manual, tractor with a rake and a forwarder; Four chipping work organization systems: chipper driven inside orchard and manually fed by operators, mobile chipper driven inside orchard with pick-up header, mobile chipper fed by means of mechanical crane, chipper mounted on a truck fed by means of mechanical crane, which was working in a fixed position in a border of the plot after wood concentration. Also two bundling organization systems were checked: bundler machine working in a fixed position after wood concentration and working inside the plot driven among the crops. Previous concentration of the materials was the best alternative for their chipping or bundling in the studied conditions. Regression models have been calculated to predict the time of work of machinery and labor for each alternative. These equations were used to implement logistic planning as the Borvemar model, which defines a logistics network for supplying bio-energy systems.

Musculoskeletal disorders: OWAS review

The prevention of musculoskeletal disorders (MSD) is very important in the world. Governments and companies are the most interested. The objective of the present work is to review the literature on the applications of the OWAS method in the diverse sectors or fields of knowledge and countries from its publication to March 2017. The use of OWAS method has been classified by categories of knowledge, by country and by year. The search was made by selecting only the main collection of the Web of Science. This was selected by the option “Advanced search” using the term OWAS (ts=OWAS) for the time period of 1900 to 2017. A total of 166 results were found, consisting of conference papers and articles in scientific journals. In conclusion, the OWAS has been applied mainly in two sectors: “Manufacturing industries” and “Healthcare and Social assistance activities”. This method needs to be complemented with other indirect or direct methods. Also, whenever the OWAS has been used, whether individually or together with other methods, musculoskeletal disorders risks have been detected, this perhaps being an indicator to review the evaluation parameters because overestimating the risk.

Prediction models based on higher heating value from the elemental analysis of neem, mango, avocado, banana, and carob trees in Guayas (Ecuador)

The energy use of biomass in rural areas is starting to interest the farmers in Ecuador. Its use is recognized as environmentally friendly, but knowledge about the raw materials to be used as bioenergy remains meager. The objective of this research was to characterize five species located in the province of Guayas: avocado (Persea americana L.), carob (Prosopis spp.), mango (Mangifera indica L.), neem (Azadirachta indica L.), and bananas (Musa acuminata L.). The elemental composition and higher heating value were analyzed following harmonized standards. These species did not significantly differ in CHN composition, being about 33.012% C, 6.232% H, 0.610% N, and their higher heating value 14.322 MJ kg−1. However, significant differences were found with respect to Cl and S: banana wood had the highest Cl and S content 1.162% and 0.134%, respectively, while avocado had the lowest Cl and S content, 0.032% and 0.063%, respectively. Fifteen mathematical models were formulated to predict the higher heating value...

Distributed network for measuring climatic parameters in heterogeneous environments: Application in a greenhouse

Abstract In Mediterranean countries of Southern Europe, the climatic conditions are usually favourable to cultivate greenhouse vegetables but not always for workers. The aim of this study was to design a network of weather stations capable of gathering data of environmental parameters related to the wellbeing of workers in greenhouses in south-eastern Spain. The unevenness of the thermal environment was studied both vertically as well as horizontally following guideline ISO 7726. The results indicate that the greenhouse should be considered a heterogeneous environment, implying that, for an evaluation of the environmental conditions related to thermal stress of the workers inside the greenhouse, measurements should be taken at different points within the greenhouse at three heights (ankle, abdomen, and head).

On air temperature distribution and ISO 7726-defined heterogeneity inside a typical greenhouse in Almería

Abstract Studies about the air temperature inside greenhouses are usually focused on the crop growth. However, the thermal environment inside greenhouses can affect the safety of the workers and also their productivity. This work focuses on the study of air temperature conditions with respect to workers following the requirements and methods gathered in ISO 7726, which indicates that measurements should be taken at different points in both, horizontal and vertical directions in order to study heterogeneous thermal environments. For the present work, data were gathered by the Wireless Sensor Network (WSN) designed in our previous work, hereby extended by an experimental campaign carried out during a complete year in a typical greenhouse in Almeriia. The aim is performing a long-term study of air temperature inside a greenhouse as well as the assessment of air temperature heterogeneity. The results, which allow characterizing air temperature inside the greenhouse, prove the existence of patterns of heterogeneity as a function of the incidence of sunlight and time of day. During the analysed period, air temperature heterogeneity is mainly present in the central hours of the day and it is higher in the horizontal dimension rather than vertically. In addition, it has been observed that the vast majority of homogeneous days correlate with cloudy days. Finally, based on the results obtained some recommendations are presented for assessing the thermal environment of greenhouses.