In Mexico, a part of the population lacks sufficient, nutritious and safe food to satisfy their daily energy needs and food preferences, how can they contribute to improving their living conditions?
Researchers from the Colegio de la Frontera Sur (Ecosur) and the Universidad Juárez Autónoma de Tabasco (UJAT) have developed a system that allows low-income families to produce up to 120 kilograms of fish, snails, and mussels in six months, in addition to 45 kilograms of edible vegetables, such as beans, chili and chives.
It is the Low Intensity Aquaponic System (SABI) that combines aquaculture and hydroponics techniques, a proposal aimed at reducing food insecurity in Tabasco, but which may well be extended to all states.
In the country, 46.2 percent of the population lives in poverty, according to data from the National Council for the Evaluation of Social Development Policy (Coneval). Of the Mexicans living in rural areas, 45.5 percent live in mild food insecurity and 22.4 percent in moderate; while, in urban areas, 40.6 percent have mild food insecurity and 16.5 percent, moderate, according to the National Survey of Health and Nutrition (Ensanut) 2012.
This project, with which Fernando Iriarte Rodríguez is seeking a doctorate, is a food production strategy in the backyard of families living in rural or peri-urban areas, which allows them to have long-term availability and access to fresh, safe and nutritious products.
It is a low-cost system because it is made up of materials commonly used in the construction industry and reuses instruments, such as PET bottles for the installation of pots and industrial plastic containers that are used as filters.
Its operation requires low energy consumption, as it uses a magnetic pump with minimal consumption to generate water recirculation. While it is environmentally friendly, since the use of the vital liquid after filling is low and the discharge of sediments minimal, in addition to using native aquatic organisms with high aquaculture potential, such as the snail and the acocil, and vegetables that are part of the food culture of the entity.
Fernando Iriarte Rodríguez, also a research professor at UJAT, explains to the Conacyt Information Agency that the project arose six years ago with the development of the engineering prototype, which has been refined and to date six systems are in operation in homes in Villahermosa and in peri-urban communities, while one more is installed at Ecosur's headquarters in Villahermosa.
What is aquaponics?
It is a production technique for aquatic and plant species inspired by the techniques that the Aztecs used through the chinampas to take advantage of the excreta of fish and microalgae to nourish corn crops.
It adds the qualities of aquaculture and hydroponics through a water recirculation system, to sustainably produce foods of high nutritional value, as a source of protein (fish), vitamins and minerals (chili, beans, tomatoes, fruits ), with a valuable social and economic impact at the local level.
Aquaponic production is an alternative in Mexico, where the agricultural sector is the largest consumer of water, using 65 percent of the fresh water consumed in the country. In 2011 alone, 77 percent of the total water withdrawals for consumptive uses in Mexico went to the agricultural sector with a consumption of 61.6 cubic kilometers, according to data from the Food and Agriculture Organization of the United Nations (FAO, for its acronym in English).
Several studies report that this technique reduces by 90 percent the requirements of the vital liquid necessary for a normal fish culture; represents a significant decrease in the costs of growing vegetables without using large areas of land, since it allows savings of up to 45 percent in fertilizers because fish production provides more than 80 percent of the elements that plants they need for their development.
While productivity levels are important, it has been documented that for each ton of fish produced annually, up to seven tons of some vegetable crop can be obtained.
However, these systems are not exempt from the risks posed by external factors such as solar radiation, temperature and natural phenomena such as cyclones and hurricanes.
How does it work?
The infrastructure of this technological initiative is made up of a tub (pool), industrial plastic containers, a system of PVC pipes and recycled PET bottles.
The SABI is filled with approximately 15 cubic meters of water, which can come from the tap, from rain or from a well, as long as it is sanitized in a basic sense. The first living beings to be sown are snails, so that they generate beneficial bacterial flora; some time later it was the turn of the tilapias, in a proportion of one fish for every two snails; depending on what they have experienced, between 250 and 350 specimens can be sown.
The water leaves the tub through a drain towards a first container, where the organic matter is sedimented, by natural biochemical processes, urea and ammonia begin to degrade to nitrites.
In a second container a manufactured substrate is deposited that encourages colonization by aerobic bacteria, of the genus Nitrosomona and Nitrobacter, which are in charge of making the change from nitrites to nitrates, since nitrites are toxic to fish.
The water that comes from the second container is taken to the vegetable cultivation circuit, which are the pipes where the pots are located. In the systems implemented by the UJAT and Ecosur specialists, 144 pots are placed, this being the minimum amount necessary to eliminate the metabolites of up to 350 tilapia. The roots absorb all the nutrients from the water, which make them grow producing fruits, foliage or seeds. In this process, the water is freed from the metabolites that could be harmful to the fish, due to the absorption of the roots which, in turn, are kept clean thanks to the presence of acociles.
Subsequently, the water reaches another container from which the water is pumped into the tub where the fish live, closing the water circulation circuit.
“In this system, all living organisms have a function: the tilapia process the balanced food producing organic matter that is consumed by the snails; they reduce it in volume; the bacteria in the settling tank transform this matter into nitrate salts; plants absorb these mineral salts; the coucils clean the plants when consuming and eliminate their roots; in this way, the water coming from the vegetable crop is biologically viable to finally be pumped into the tilapia crop ”, explains the teacher Fernando Iriarte.
To date, six Tabasco families benefit from the SABI, all of which currently have it in operation. The added value offered by this system - unlike other models that have been developed in Mexico and other parts of the world - is that it has been functional for almost three years in the backyard of homes.
Throughout this time, Fernando Iriarte Rodríguez and his thesis advisor, Dr. Manuel Mendoza Carranza, an Ecosur researcher, have validated the system, installed it and accompanied users in their operation during the six months that the first production cycle.
“The results, regardless of the fact that healthy foods are obtained, free of toxins, safe and that they are always there, have shown benefits such as increased food security for families, their empowerment by consuming food that they produce themselves and the organization they have. to take charge of the system ”, explains Fernando Iriarte.
Dr. Manuel Mendoza Carranza, researcher at the Department of Sustainability Sciences at Ecosur, Villahermosa unit, says in an interview that this project has multiple contributions from an academic point of view.
In the first instance, the results that the work is giving will allow Fernando Iriarte to obtain a doctor's degree. The second is that it provides novel adjustments in its operation with respect to other systems at the national and international level, which will have a strong scientific-technological impact.
He points out that another value of the system is its economic and productive approach. "The first experiment that was carried out was to validate its efficiency, both in terms of management and the economic-productive part, resulting in that the systems we have installed, almost all have a similar behavior, it means that we have a homogeneous system and that from the scientific point of view is proving its efficiency ”, abounds.
So far they are already contemplating the development of a couple of scientific articles, one focused on the technical characteristics of the system, how much is sown and how much is produced; and an economic analysis evaluating that if a person invests in the installation of the SABI in their home, in what time they will see their investment recovered.
Additionally, the SABI is testing that it can be used to grow more than 90 different species of plants, including tubers such as radish and garlic, of which it was not known that it was possible to produce them by aquaponics.
It should be noted that a patent is pending as a utility model between Ecosur and the developers, in order to have greater security and that the system and its advantages reach the people.