Use of fish farming water in the irrigation of plants with economic interest: a case study in the Brazilian Backwoods

Most Brazilian soils are known to present a low natural fertility. This problem is most evident in the Brazilian Backwoods, mainly due to their edaphoclimatic conditions. In opposition to the agriculture challenges, on the other hand, activities of fish farming have been growing in Brazil. However, aquaculture is an activity that generates effluents with a high amount of organic matter (OM) and nutrients. In a dual perspective, to solve the problem of the low soil fertility and the toxic potential of the effluents generated in the fish farming, the implementation of integrated farming systems could be an interesting alternative, proposing to reuse the water from fishponds by enhancing OM and recycling nutrients via irrigation. Thus, the present work aims to carry out a chemical study of water from fishponds for use in irrigation of plants of economic interest. The soil collected and characterized in this study was a dystrophic Red-Yellow Argisol (dRYA). Samples of FFW and the dRYA was characterized and its physical/chemical attributes determined. According to the results, chemical characteristics allow the FFW the in the irrigation of plants with economic interest. Since dRYA is low in OM (2.12%), TOC (0.43%) and %V (47%), soil samples showed a non-natural fertility at a level of considerable profitability. Thus, according to our findings (about FFW and dRYA chemical characterization), it is possible to consider the use of water from fish farming in the soil/plant irrigation. At future, agronomic assays will be carried out in order to evaluate the real effects of the FFW irrigation in an organicagroecological farm, in a family nucleus system of production, in the Brazilian Backwoods. Key-words: Fish Farming Water, Brazilian Backwoods, Organic Matter, Organic Agriculture In recent decades, Brazil has passed from a major food importer to one of the most important exporters. In this sense, agriculture is extremely important for the overall performance of the country economy (Embrapa, 2018). Actually, one of the challenges in agriculture is the quality of the Brazilian soils, which are mostly low in natural fertility; since they are high weathered, acidic and poor in organic matter (OM) and nutrients, resulting in a low agricultural productivity (Manzatto et al., 2002). This problem is aggravated in the Northeast Region, which has a semiarid climate, characterized by a water deficit and an irregular rainfall pattern, resulting in a poor environment for agricultural production (Buainain and Garcia, 2013). On the other hand, fish farming activity has been growing in Brazil. In 2018, the country became the 4th largest fish producer in the world. Thus, Brazilian fish farming is a growing activity with a great potential due to the country water resources and favorable climate (Medeiros, 2019). In the Northeast Region, fish farming has been prominent, since the low rainfalls and the periods of prolonged drought make it difficult for ruminant creation and commercial-proteins production. While 17 ML of water are needed to produce 1 kg of cattle protein,