What is happening to the weather in Brazil?
There are two independent and simultaneous phenomena: one is the atmospheric block resulting from a high-pressure zone formed on the Atlantic that hinders the entrance of cold fronts in the state of São Paulo. The block lasted longer than normal, preventing the entrance of cold fronts in the summer. A new block appeared in December, which has just recently dispersed. Another factor is the climate variation caused by a natural cycle in the Pacific and the Atlantic Oceans, which reduces the frequency and strength of the cold fronts that come from the South Pole toward the Brazilian Southeast and that would generate the normal amounts of rain.
Where is Brazilian freshwater located?
About 80% of Brazil's freshwater is in the Amazon region; the other 20% supply a wide extension of the Brazilian territory, where 95% of the population lives. In Brazil, the annual average river outflow is equivalent to 12% of the world availability of water resources. If we consider the outflows deriving from rivers located in Uruguay, Paraguay, and in countries in the Amazon region, this percentage can grow as far as 18% of the global total, the National Water Resource Plan reports. This set of water courses is distributed through the Brazilian territory and can be divided into 12 Hydrographic Regions: Amazonian, East Atlantic, Western Northeast Atlantic, Eastern Northeast Atlantic, Southeast Atlantic, South Atlantic, Parnaíba, São Francisco, Tocantins-Araguaia, Uruguay, Paraguay, and Paraná regions. Generally speaking, there is a very comfortable water situation: 33,376 m3/inhabitant/year. The United Nations (UN) estimates that the volume of 2,500 m³/inhabitant/year entails enough water to maintain aquatic ecosystems and social and economic human activities. However, a closer observation reveals an uneven distribution of water resources. While an inhabitant of Amazonas state makes use of 700,000 m ³ of water per year, an inhabitant of the São Paulo Metropolitan Region has only 280 m³/year. In the Eastern Northeast Atlantic HR, which encompasses the states of Piauí, Ceará, Paraíba, Rio Grande do Norte, Pernambuco, and Alagoas, the ratio is 1,145 m³/hab/year, a consequence of the rainfall variation in this area. Meanwhile, in the Paraná (Tietê basin) and the Southeastern Atlantic (Coastal Rio De Janeiro) sub-regions, the low water availability per inhabitant (from 1,000 to 1,700 m³/inhab/year) is a result of high population concentration.
Which technologies are recommended to adapt properties to collect rainfall, recharge water tables and revitalise springs and streams?
"Mini-dams" or "mini-ponds" to capture downpours since, as they promote the infiltration of water into the soil and intercept sheet erosion flows, they can facilitate increased soil moisture and the rise of the water table. The main role of these technologies is to rehabilitate areas degraded by rain, in addition to revitalizing and perennializing good quality water tables and alleviating droughts and floods. Technologies to build mini-dams have been implemented in different regions of the country since 1993, bringing environmental, social and economic benefits for the local populations. The construction of 150,000 mini-dams with Embrapa's direct involvement has been catalogued. In 12 years, over 600 technicians from different state EMATERs (Technical Assistance and Rural Extension corporations) have been trained . After the training of technicians and induction through TV shows, magazines, newspapers, etc, it was possible to build another 300,000 dams via the private sector. It is currently estimated that there are about 500,000 mini-dams and mini-ponds in all of Brazil. In addition to the technology to build such dams, other water and soil conservation technologies are available, including no-till farming, integrated systems, and the terracing - an agricultural technique that entails multi-levelled farming to restrain erosions caused by water draining, especially in areas with steep slopes. Thus, rainwater, as it flows off the surface, loses momentum and removes less sediments from the soil.
It is also possible to adopt the integrated crop-livestock-forest systems (ICLFS), no-till farming, terraces in grain production areas, and terraces in the areas destined to fruit production, planted forests, and pastures. This action would guarantee the "production" of water in the farms with the intensification of water infiltration into the soil, which would raise aquifer and water table levels, allowing the flow of water courses to become more regular during the year and reducing the volume of the instantaneous flow that caused floods after intense rains..
Other technologies worth highlighting are:
- Underground dams to perfect and to balance the production process, promoting higher stability and resilience, especially in the Brazilian Semiarid agroecosystems;
- Reuse of water in agriculture and use of inferior quality water (residue from other animal and plant production systems, or of industrial, urban or saline origin);
- Soil and water conservation practices in irrigated production systems, including soil management, no-till farming, crop rotation, sequential cropping, intercropping, and artificial soil protection aiming at reducing evaporation, wherein water is the main variable; and
- Improvement of irrigation systems aiming at increasing efficiency and optimization of water use and energy, including site-specific irrigation and night irrigation.
With regard to wasted water, which technologies can reduce this problem?
Sustainable agricultural intensification practices, in which Brazil has stood out, will have great impact in the hydrological cycle, with bigger recharge of aquifers and better regularization of the water flow throughout the year. Integrated Crop-Livestock-Forest Systems (ICLFS) are also another option, as they are a strategy that provides sustainable production by integrating agricultural, husbandry, and forestry activities in the same area. Combined with intercropping, crop succession or rotation, the adoption of ICLFS leads to a substantial protection of soil and water. These are practices that not only help farmers to increase productivity and to deal with the challenge to minimizing agricultural greenhouse gas emissions, but also reduce the pressure on soil and water resources . Nowadays, there are about 60 million hectares of degraded pastures in Brazil that could be occupied by integrated systems and produce clean water in the future.
Is agriculture the sector that most uses water in the world?
Data from the UN World Water Assessment Program inform that agricultural segments comprise around 70% of the water consumption. In some emerging countries where there has been fast economic growth, this percentage can reach 90%. In Brazil, about 72% of the outflows consumed would go to agriculture - especially irrigated agriculture, 11% quench the thirst of herds, 9% are distributed through cities and 1% supply agricultural areas. These figures are well publicized, but they do not consider the quality of the water that returns to rivers, in the case of the industry and the urban sector, or the amount of water evaporated in the dams that are hydropower plants as well. The issue is not only about taking water from rivers, but also about making it unavailable for other uses. Therefore, it is necessary to relativize the assertion that "agriculture is the largest consumer of water in the world". To have a correct number, we would have that to remake the calculations, using a methodology that considers these factors.
Is it possible to optimize the use of water in agriculture?
That requires the use of infrastructure and technologies that are already available. In irrigated agriculture, we have to prevent water losses in the pipes and canals that lead the water from a source to the agricultural area, and in the distribution of this water within an agricultural area. It is important to only use the amount of water that the crop needs, in accordance with technical knowledge and recommended equipment. For dryland or rain-dependent agriculture, there are similar agricultural practices that help to conserve rainwater, e.g. no-till farming and the use of contour lines (terracing) in the crop area.
Will there be scarcity of water for agriculture this year?
The data available do not point to grave or general alarm situations. It is not expected that the dry spells that took place at the beginning of the 2014 rainy season and in January 2015 cause significant losses in the production of grain, fruit, and meat. The information available thus far does not give evidence of significant losses in the 2014/2015 crop year, since dry spells are common and have occurred systematically without drastically affecting the Brazilian agricultural production, which has been systematically incorporating technological advances and presenting significant productivity and production gains throughout the last decades. However, there are local situations of greater scarcity, especially surrounding major cities of the Brazilian Southeast, which will demand follow-up and attention, especially during the winter of 2015. A similar situation occurs in the Western portion of the state of Bahia, with important effects on grain production in the region.
What are the expectations in terms of climate variation by the end of the 2014/2015 crop year?
Information on the climate and weather forecasts for the period of February to April 2015 has been analyzed. According to INMET, the Brazilian National Institute of Meteorology, observations on the temperatures of surface waters in the equatorial Pacific and tropical Atlantic oceans indicate that, in the region the El Niño phenomenon typically occurs, anomalies have diminished, showing conditions for neutrality. However, there has been notice of strong heating in the west Pacific waters, close to Indonesia, which can have a strong negative influence on the climate in the South and Southeastern regions of the country. On the other hand, in the tropical Atlantic, a pattern of anomalies in surface water temperatures has been observed, which tends to keep the Intertropical Convergence Zone (ITCZ) further north, disfavoring rains in the Brazilian North and Northeast. INMET's stochastic-statistical model forecasts precipitations from February to April 2015, with below average values in the South and part of the Brazilian Southeast, except for mid-north Minas Gerais state. Rains are also forecast to be below average north of the Brazilian Northeast for the same period, in response to unfavorable thermal variations in the Tropical Atlantic at this time. The model also forecasts a decrease in rains in part of the Midwest (especially in the state of Mato Grosso). Meanwhile, in part of the North (especially Amapá), Northeast (especially the mid-south of Bahia), and Midwest (especially Goiás) regions, above average values are forecast. Above-average temperatures in the North and the northern part of the Northeast, as well as close-to-average temperatures in the rest of the country are also forecast.
What is the impact of the lack of water on production in the Brazilian states where water scarcity has been most severe?
São Paulo, Minas Gerais, and Rio de Janeiro are the main vegetable producers in the country, especially leafy vegetables, carrots, and tomatoes, and a good portion of the vegetables consumed in the Brazilian North and Northeast come from these three states. It is also important to consider that at least two other major vegetable producing regions have been affected by water insufficiency for at least two years − Chapada Diamantina, in Bahia, and the region of Mossoró, in Rio Grande do Norte. The former is responsible for the supply of potatoes, carrots, and other vegetables to a fair share of the Northern/Northeastern consumer market, and the latter, for most of the melons the country exports, which, by the way, is the crop that has suffered the biggest reduction in crop area from the vegetables group. Another important vegetable producing region, especially carrots, in the state of Bahia, the Irecê Microregion, has experienced a 10% decrease in the carrot crop area in the second half of 2014, but analysts consider that this decline was much more due to the low prices reached in the first semester than to rain scarcity. Therefore, situations of greater irrigation water scarcity, especially surrounding major cities of the Brazilian Southeast, have to be monitored with attention, especially during the winter of 2015, when the vegetable supply can be affected.
Does commercial animal husbandry use a lot of water?
The pressure from livestock activities on water resources is relatively small. The demand for drinking water is a response to room temperatures. Nonetheless, forage production has a high demand for water flow, and it is necessary to follow the impact of the water crisis on pasture supply in the main producing regions.
How can agriculture better face the difficulties imposed by the water crisis?
One way is to promote "reserves" - which simply means building reservoirs to store water and use it for irrigation and, if possible, for other ends - with the broad dissemination of soil and water conservation practices and the construction of small and medium dams in the lowest part of the springs in the micro-basins that compose the main watersheds. As previously stated, technologies to build dams and soil and water conservation technologies such as no-till farming, integrated systems, and terracing are also already available. With suitable public policies, it will be possible to encourage no-till farming, and the construction of terraces in grain production areas and in the areas destined to fruit production, planted forests, and pastures. This action would guarantee the "production" of water in the farms with the intensification of water infiltration into the soil, which would raise aquifer and water table levels, allowing the flow of water courses to become more regular during the year and reducing the volume of the instantaneous flow that caused floods after intense rains. Considering the annual average precipitation in Brazil and the implementation of these water "production" and "reserve" activities, there would certainly be enough water for human and animal supply, for energy production, and to significantly increase irrigated areas in the country. The implementation of the new Forest Code started a massive process to recompose Permanent Preservation Areas with the reforestation of riparian vegetation areas that will prevent sedimentation and will give more fluidity to water courses in watersheds.
What should farmers do to make good use of water and avoid wasting it?
There is a series of technical criteria that can be used for this purpose. There is the example of the use of the dead cover (crop residue), which can help to conserve water in the soils. Measuring soil water levels through sensors can help one define the amount of water to be applied by an irrigation system, depending on the stage of the crop. That varies according to region, crop, and the agricultural production system that is being used. In a nutshell, farmers need to use technical criteria for the water they will use in the irrigation.
Which technologies used in agriculture contribute to saving water?
There are some technologies, which range from measurements of the amount of the water in the soil and of plant needs, and the conservation of water in the soils through the use of dead cover (crop residue) to reduce evaporation, to plant genetic improvement, which seeks varieties that are more resistant to water deficits. Deficit irrigation can also be practised, which consists in the application of an amount of water that is lower than the plant requirement.
In addition to the use of technology, how can farmers contribute to saving water in the fields?
Farmers' training is essential to increase the adoption of soil, plant and irrigation management technologies, which can contribute towards a more sustainable use of water in agriculture, especially when irrigation will be used. In addition to higher economic yield, a better quality of the production can be obtained, as water excess can be harmful in many cases. There are economically viable techniques for that.
What is necessary to cope with the scarcity of rain and water in agriculture?
It is necessary to plan and implement water storage during the rainy period or in water courses in which this is possible. It is important to reserve water for agriculture and, if possible, for other purposes as well, such as the generation and supply of energy for cities and industries, which entails the need for an integrated management of water resources.
Which are the most irrigated crops?
According to IBGE, sugarcane, rice, soybeans, maize, beans (Phaseolus vulgaris), cowpea (Vigna unguiculata), orange, coffee, onion, watermelon, cotton, and wheat are the most irrigated crops in Brazil. With regard to beans and cowpeas (Phaseolus and Vigna), important staple food for the Brazilian population, only 2.6% of the farming establishments that produce them use irrigation. As for coffee and maize, only 0.85 and 16.0%, respectively, use irrigation.
What is the importance of irrigation for agriculture?
There are areas where the amount of rain does not meet crop water demands, hence we have to irrigate to have production. That is the case of arid and semiarid regions such as the Brazilian Semiarid. Meanwhile, in other regions like the Cerrado area, mostly located in the Brazilian Midwest, there are amounts of rain that can meet crop water needs, but only for part of the year. If we want to produce all year round, we have to make use of irrigation. Even in rainy periods, irrigation can prevent water scarcity caused by dry spells, and thus increase productivity.
Is irrigation simple?
The practice of irrigation requires the knowledge of how much water the plants require so as to use it without wasting it. For that purpose, the amount of water present in the soil and local weather conditions, which make the plant consume more or less water, must be measured. In addition, equipment, energy, and suitable techniques for the correct application of water for different crops are required.
Is the water used in irrigation completely consumed by the plants?
No. Part of the water used in the irrigation stays in the plant, but a large part of the water comes back to the atmosphere (through evaporation from the soil and through plant transpiration), flows to lakes, reservoirs and rivers, or is drained into the water table (groundwater).
Do all plants require the same amount of water?
No. There are plants that need lesser and greater amounts of water, and there are plant growth stages at which there are lesser or greater water requirements.
Could irrigation water be saved for urban use?
Irrigation water is absolutely necessary for food production in agriculture. The proposal is to use water rationally and efficiently to benefit society as a whole. Agricultural irrigation conducted with efficiency and economy can benefit urban use. If the water from a large reservoir is used to generate energy, irrigate crops, and supply houses and industries, the responsibility for the good use of water is shared by all.
Which irrigation methods are the most used in Brazil?
The pressurized method has been the most used (35% in the conventional system, 19% in the central pivot system, and 8% in localized systems), followed by the surface method (24% in the flood system and 6% in the ridge system). Other methods (manual watering using watering pots, hoses, buckets, cans) correspond to only 8% of the total irrigated area in Brazil.
How can we improve the management of the use of water?
The growth of urban and industrial areas have directly influenced in the increased demand for water from water sources. Another sector that has high water demand is the electric energy industry, which started to require a bigger energy-generating park, which in turn, caused the need for hydropower exploits. In a chain reaction, the demand for increased food production found in irrigated agriculture the appropriate channel to meet such demand. The efficient management of water resources underscores different uses such as water supply for cities, energy production, leisure, food production, industries, etc., which require attention in the search for solutions to ensure water sufficiency. Hence the importance of resource management to be focused on managing the demand (rationalization of the use), managing the supply (water production), and managing the quality of the resource for its different uses.
* Document based on information from Embrapa, INMET, and ANA.