“Biosaline agriculture is an alternative to the use of brackish waters and soils affected by salts in plant production…”
Claudivan Feitosa de Lacerda is a professor at the Federal University of Ceará – UFC, an agronomist and a M.Sc from UFC, with a Ph.D in plant physiology from the Federal University of Viçosa.
Hans Raj Gheyi is a professor at the Federal University of Campina Grande – UFCG, an agronomist from the University of Udai Pur, a M.Sc from the Agricultural University of Punjab and a Ph.D from the Catholic University of Louvain.
José Francismar de Medeiros is a professor at the Federal Rural University of the Semi-Arid – UFERSA, an agronomist from Mossoró College of Agriculture, a M.Sc from Federal University of Paraíba and a Ph.D from University of São Paulo.
Biosaline agriculture is an alternative to the use of brackish waters and soils affected by salts in plant production, when associated with the use of good management strategies. It can also include different types of activities, as salinity is associated with other problems typical of arid and semi-arid regions.
In this context, a first challenge we have is to expand the concept of biosaline agriculture in Brazil, that is restricted to the use of brackish water/saline waste and soil affected by salts, as if they were isolated factors in the semi-arid region. There is no way to expand this activity with this restricted vision. Rainfall regimes, recurrent droughts, wastewater, availability of water resources, climate change and actions for the propagation of technology must be inserted in the context of biosaline agriculture.
The existence of extensive areas of soil affected by salts threatens the sustainability of irrigated agriculture, since the expansion of agricultural frontiers collides with environmental issues. In this context, the possibility of restoring the soil and the potential for using saline areas need to be considered.
Many studies demonstrate the high costs of recovering soils affected by salts, that are often inaccessible to small farmers, especially when it is necessary to install an underground drainage system. Another problem is that drainage cannot occur on single properties/farms or in isolated cases, but must be carried out at the watershed (drainage basin) level, that is, there must be public or cooperative action.
New management strategies and use of these areas must be envisaged: revegetation projects with adapted species or cultivation of halophytes with forage potential can be viable alternatives for improving soil conditions and generating income. In some areas of sodic soils, called “irrecoverable”, other activities may be a solution, such as shrimp farming, that has expanded in inland areas of the State of Ceará, using part of these soils.
In the Brazilian semi-arid region there is also the occurrence of brackish water, mainly of underground origin. There are different realities in this region when it comes to the availability of water. In the city of Mossoró, for example, the waters of the Calcário Jandaíra aquifer are brackish, but the wells present flow rates greater than 60 m3/h. These waters have been used in mixtures with water coming from the Arenito Açu aquifer (low salinity, but deeper and high flow), a fact that favored the expansion of melon farming in the State of Rio Grande do Norte, especially in the last decade, with this activity being practiced even by large companies in the region.
On the other hand, the brackish waters in the crystalline aquifer, predominant in the Brazilian semi-arid territory, have low flow rates. It is estimated that there are more than 100,000 wells located in the northeastern semi-arid region, most of which have a flow rate between 1.0 and 2.0 m3/h. A study that evaluated 23,000 wells in the State of Ceará found an average flow rate of 2.6 m3/h in crystalline wells. Another study in the State of Ceará demonstrated that these sources are more useful for family agriculture, especially in farming systems that use smaller volumes of water. For these conditions, the farming of cactus pear, supplementary irrigation of annual crops and systems involving fish and vegetables (hydroponics, halophytes or seedling production) have a greater possibility of success than the coconut farming (a salinity-tolerant species), that is limited by high water demand and low water productivity from wells.
It is important to emphasize the need for studies in partnership with farmers and the elaboration of public policies that may favor the expansion of biosaline agriculture in the Brazilian semi-arid region. The partnership with public and private institutions, city halls and farmers’ organizations is essential for the success of this activity. It is necessary that the biosaline agriculture theme be more comprehensive, envisioning the soil and water resources usage and the reuse of water, within the context of the sustainable production of fruits, grains, fodder, ornamental plants, wood, biofuels, pharmaceuticals, etc.