Irrigation in Brazil: need and strategic option

  Was irrigation the cause of the water crisis that occurred in Brazil in 2014-2015? Could it be the cause of a new crisis in 2021? Science can help understand the situation, a reason for debates and controversies.

   In Brazil, 49,8% of water collected from water sources is used for irrigation, according to the National Water and Basic Sanitation Agency (ANA). However, the phrase “irrigation consumes 70% of water” was widely circulated a few years ago and may return to the headlines. But this number refers to an estimate of the use of water by agriculture on a global scale and, mistakenly, has been remembered and used.

     The analogy with looking at a “half-full” or “half-empty” glass of water can help to understand what irrigated agriculture or, simply, irrigation represents, in a country where the countryside is fundamental to economic and social activity. and environmental.

     Agriculture is a risky activity and irrigation implies higher production costs, but at the same time it can reduce risk and increase profit, since its practice is necessary in regions where the water demand for plants exceeds the water regime. rains. Irrigation can also be a strategic option in other regions, to guarantee production in the event of dry spells, or even to increase productivity.

     It is a fact that agriculture is the largest user of water in the world. According to Brazil's Environmental Economic Water Accounts (IBGE and ANA), in 2017, for every R$1,00 of gross value added generated by economic activities in Brazil, 6,3 liters of water were used. If we add agriculture, livestock, forestry production, fishing and aquaculture, the ratio reaches 96 liters for every R$1,00.

     The Irrigation Atlas (ANA) shows that we have 8,2 million hectares irrigated; The share of irrigation in the value of agricultural production can reach 100% in many Brazilian municipalities and, in some of them, the total value of agricultural production is hundreds of millions of reais. The productivity of an irrigated crop exceeds that of a crop without irrigation by 2 to 3 times. There is the possibility of increasing the Brazilian irrigated area by 55,9 million hectares and the question arises, how much would we stop producing without irrigation, or even, how much will we stop producing if we do not increase the irrigated area?

     Most of the water used (and not consumed) in agriculture returns to the atmosphere through evaporation and transpiration that occurs in plants. Another part of it is stored in the soil and water sources. It's the hydrological cycle. But a “third part” of water is present in the vegetable raw material that we process or transform and in the food we consume. Therefore, when we waste food, we also waste water.

     The availability of water in a region can vary over the years, leading to scarcity, which can be physical (there is no water available), economic (water is available, but there is no infrastructure for its use) and institutional (there are water and infrastructure, but the water cannot be used). However, reserving water carefully can minimize the possibility of physical shortages.

     The FAO predicts a 47% increase in global food demand by 2050. Thus, irrigation in Brazil should contribute to increasing food production, but it should improve its effectiveness (what to do) and its efficiency (how to do it). And we have the technology for that.

     In certain situations, water can be applied in a smaller quantity than an agricultural crop requires. It is deficit irrigation, which when used with technical criteria can be an interesting strategy, in conditions of water restriction or scarcity.

     Automation can help with irrigation management (when and how much to irrigate) and turning an irrigation system on and off (how to irrigate). The geographic information system, precision agriculture, digital agriculture, information technology and connectivity can also help improve irrigation management in agricultural areas of different sizes. But we must increase and improve the training of the agricultural sector, so that this happens more intensely.

     The use of wastewater and effluents should also be encouraged and improved to meet the water needs of plants in some situations, reducing the withdrawal of water from its sources, in addition to replacing the energy used in irrigation and from hydroelectric plants with solar energy and wind energy.

     However, any solution and technology must complement agronomic knowledge, which is the basis for the effective and efficient use of irrigation. Even planting more drought-tolerant cultivars can help reduce the volume of water used in agricultural production.

     The water crisis can lead farmers to change irrigation practices and, when this occurs, society needs to be informed about such attitudes. In this way, the dissemination of information in relation to irrigated agriculture can be based on data and facts and the perception of the glass of water will occur from a scientific perspective. We have the technology and knowledge for this!

Luís Henrique Bassoi

Researcher at Embrapa Instrumentação