New Technologies in greenhouse horticultural crops

By Pilar Lorenzo, Mª Cruz Sánchez-Guerrero and Evangelina Medrano, researchers from the Agro-Food Engineering and Technology Area of the IFAPA Center La Mojonera (Almería)

The maintenance of the competitiveness and the presence in the international markets of the Almerian horticulture requires an increase of the productivity, with the highest quality, to maximize the benefits, reducing the environmental impact. The variables of climate and nutrition influence the growth and development of the crop and, the adequate management of these allows to maximize the difference between the income and the associated costs.

Two options currently coexist in the incorporation of technology to improve the climate of Mediterranean greenhouses: active and passive, depending on whether or not they involve energy consumption. In both trends, the technological endowment should contemplate practices that respect the environment that guarantee the efficient use of inputs, especially energy, water and fertilizers.

The implantation in the productive system of our province of the existing technological options is minimal, with regard to climate control, as reflected in the publication “The protected horticultural production system of the province of Almería” (García-García y col., 2016, web Servifapa). However, from the point of view of the research in our institution, the IFAPA in its center La Mojonera de Almería has advanced considerably in the knowledge of the improvements that can offer on crops the incorporation of different technologies and their management adapted to the specific conditions of Almeria. In addition, the sector has the necessary technological support from the auxiliary company in the area to address the changes in the production model, as shown by its market projection towards other countries, both European and South American.

Currently in the Center IFAPA La Mojonera through research and transfer projects financed with funds FEDER and ESF: ‘Sustainable innovation in protected horticulture’ and ‘Participatory innovation for a sustainable protected horticulture’ we are studying the influence on crops of the application of different technologies to improve climate and nutrition in Mediterranean greenhouses.

Within the passive methods of heating, thermal storage, by means of polyethylene sleeves filled with water installed between the cultivation lines, has shown a positive effect by increasing night temperatures and production in a culture sensitive to low temperatures such as pepper. Currently this system is ready to be visited in a greenhouse parral with pepper cultivation in soil.

In parallel, we are evaluating the synergistic effect on the increase of night temperatures of the combination of these heat accumulators with the installation of thermal screens in multi-tunnel greenhouse structures with pepper culture in substrate.

On the other hand, the accumulated experience and the current state of the technology allows to accept as feasible the active management of the greenhouse through the use of renewable energies (solar and biomass) and storage systems (solar, energy or CO2). In this sense we are dealing with the study, design and evaluation of hierarchical control systems that allow us to optimally manage the new energy supply schemes. This work is the continuity of the project ‘BIOGREEN: Advanced model of production in greenhouses’, funded by IDEA-CTA, which has provided the IFAPA Center of La Mojonera with a valuable infrastructure that makes it possible to develop strategies for the use of renewable energies (Termosolar and Biomass) for the active management of the greenhouse climate, the use of CO2 from the combustion of biomass to increase its concentration inside the greenhouse as well as the development of an interchangeable greenhouse cover, which allows to go from plastic to mesh. The general objective of these activities is to achieve continuous and quality production throughout the year, guaranteeing the supply of products to national and international markets.

Regarding the efficient use of water and fertilizers, substrate cultivation allows the reuse of nutritive solutions through recirculation systems, reducing the environmental impact as well as the water and fertilizer expenditureç

On the other hand, the reuse of leachates can lead to imbalances in the composition of the nutrient solution as well as an accumulation of excess salts. At present we are evaluating the use of selective electrodes that are connected to the irrigation pipeline and with the help of a series of automations allows to analyze in real time the chemical composition of the recirculating solution. The final objective is to be able to use this information for the automatic adjustment in the irrigation head of the proportion of fertilizers to contribute to the crop as well as to determine the moment in which the accumulation of salts exceeds the tolerance of the crop and to be able to act accordingly. Likewise, it is worth highlighting the European project ‘FERTINNOWA: ‘Transfer of innovative techniques for a sustainable use of water and fertilizers’ funded by the European Union, whose main objective is to create a meta-knowledge database on the use of innovative technologies and management practices in horticultural systems with fertigation.

FERTINNOWA will also design a platform for the exchange of existing knowledge that will evaluate already available and / or novel technologies (innovative potential, synergies, gaps in knowledge and / or implementation, barriers, etc.) in these crops and will ensure the dissemination of results to all the actors involved, regarding the most promising technologies and best management practices. Within this project, IFAPA is evaluating the use of artificial lagoon systems together with the action of a series of bacteria for the purification and desalination of water from the drains of greenhouse horticultural crops for subsequent reuse in irrigation, or it is important to ensure that the effluents that go into the environment have a minimum load of fertilizers, especially nitrates. IFAPA leads the technology exchange work package and in October 2018 it will organize in Almería the final project Congress where the results of the technologies evaluated in the different participating countries will be shown and a stand area will be set up so that the companies related to irrigation and fertilization can offer their technologies.

We must take advantage of the climatic conditions that have made possible the development of greenhouse systems in Almería, although we must take into account that our market niche is focused on the winter months, so it is necessary to incorporate technologies that optimize the use of radiation and allow to achieve optimum temperature and humidity ranges for the crop.

Currently a limiting factor is the shortage of water so it is necessary to increase the efficiency in the use of water by using mechanisms to adjust the contribution to the demand of the crop, as well as its subsequent reuse and purification

Finally, as a conclusion, the need to continue advancing in the study of the best technological options to be implemented in the productive system of the Almeria greenhouse is defined in order to define a MODEL well adapted to the characteristics of this area that allows reaching the current objectives to increase productivity of high quality and in a manner that respects the environment.

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