Irrigated agriculture is the most important tool to ensure excellence in agricultural management in the sugar-energy sector. Among the crops with the greatest weight in the Brazilian economy, sugarcane was one of the last to invest in the development and adoption of irrigated production, despite decades of use of equipment to dispose of vinasse and wastewater. The exception is with some regions of the Northeast.

In times of agriculture 4.0 and appreciation of environmental issues, irrigated production is the determining factor for a modern agribusiness to optimize resources of all kinds and ensure productivity with sustainability required by the historical moment. Irrigation emerged about 6,000 years ago in Mesopotamia. It was through it that a transformation of land use and society like no other activity had ever done. After millennia, today, through irrigation, a reliable production of food and clean energy is sought.

Therefore, irrigation is perhaps the most important and beneficial intervention intentionally promoted by man on his environment. In the developed world, at the highest levels of discussion on food security and sustainability, the intensification of production through irrigation is considered the most appropriate strategy to increase world food production and clean energy in a sustainable way.

In the context of climate change, with an increase in the frequency and intensity of droughts in the main producing regions, associated with the rapid migration of sugarcane production to the Cerrado, it is irrigation that will ensure attenuation of the abrupt fluctuations in the mills' milling. It will also reduce the sharp drop in productivity from the beginning to the end of the harvest and dilute the growing capital and funding costs per ton of sugarcane and sugar, per liter of ethanol, per joule of energy, per cubic meter of biogas, among others. other benefits.

These abrupt milling fluctuations, in addition to substantially raising the industrial and agricultural cost of each ton of sugarcane, bring almost unavoidable inconvenience to the financial management of machinery and staff. For example, after a drier year, the demand for sugarcane reform can go from 15 to 17% to 25 to 30%. With this vision of insurance for business sustainability, many mills have substantially accelerated investment in an irrigated system for a fraction of their areas.

The Myth of Rustic Cane:
Although irrigation is considered by world leaders and state-of-the-art plants as one of the main strategies to ensure environmental sustainability, food security and the production of renewable energy, there is still considerable misinformation. An example is the myth that sugarcane is a rustic plant and therefore does not need much water or irrigation.

Indeed, this argument has also been used recurrently at the beginning of irrigated production of several crops that today make extensive use of irrigation in the country, such as coffee, oranges and some grains. Perhaps, if we compare sugarcane with some other crops, we can say that this statement is true, as sugarcane needs less water to survive.

However, in the context of commercial production, the objective is not the mere survival of the plant. On the contrary, in a sustainable production system, the best conditions are offered for the crop to express its genetic potential and produce efficiently. Therefore, it is not enough for sugarcane to survive.

In the past, sugarcane was produced only on the coast and in the Atlantic Forest biome, and, in fact, in an environment with a better distributed water supply throughout the year. But even so, often drier years brought strong negative impacts to production. Over the years, and for various technical, logistical, economic and social reasons, crops migrated to the Cerrado biome, mainly in São Paulo, and later to Minas Gerais, Mato Grosso, Mato Grosso do Sul, Goiás, Tocantins and, finally, Pará.

Today, more than 50% of the country's sugarcane is produced in the Cerrado, whose dry period can last for 4 to 7 months. In this environment, not only is the development of the plant tremendously reduced, but also the sprouting and longevity of the ratoons. Following the logic of Liebig's Law of Minimums, the most restrictive production factor may not be water in a context of very low technological and management improvement.

But, currently, the sector shows great advances in varietal management of fertility, weeds, phytosanitary, not to mention the great change from manual harvesting of burnt cane to mechanized harvesting of raw cane, and many other technological and managerial improvements. Even so, due to water restrictions, a significant increase in productivity has not been achieved for decades.

Therefore, water, which has always been the main production factor, has grown even more relevant. Other production factors evolved, but production also migrated to regions with an increasingly scarce water supply. And why not mention the challenges brought by global climate changes that have produced severe and frequent periods of drought in sugarcane producing regions?

The myth of water consumption by irrigation:
Initially, note that it is more appropriate to replace the word consumption with the word use. Consumption brings a mistaken view that the passage of water inside the plant causes it to be permanently lost, disappearing from the water system: which is far from being true.

An inattentive and non-systemic view can lead to a mistaken conclusion that irrigated sugarcane, as it uses water from rivers, dams or wells, ends up using more water than rainfed sugarcane. However, rainfed sugarcane also needs water to survive and produce. It, like any other plant, in addition to absorbing part of the rainwater with its roots, transports it through the culms, reaching the leaves; then the water is released into the atmosphere by transpiration.

Irrigated sugarcane is identical to rainfed sugarcane, but, in addition to rainwater, it also transpires the water given to it by irrigation during the dry period. In a more holistic view, we need to bring productive efficiency to the center of the conversation. Irrigated sugarcane, as it suffers less water and nutritional stress, is able to produce more stalks with each drop of water it uses.

Embrapa research has shown that irrigated sugarcane , when compared to rainfed sugarcane, extracts more of its genetic potential and produces up to 50% more stalks and sugar for the same amount of water used. For example, an upland cane field that received 1200 millimeters of rain and produced 80 tons per hectare obtained an efficiency of 66 kilograms per millimeter.

In the Cerrado, with the technology we have today, we could add 300 millimeters of irrigation and produce, in the same area, 120 tons, that is, an efficiency of 80 kilograms per millimeter. Or we could add 450 millimeters of irrigation to 1200 millimeters of rain and produce 150 tons per hectare, generating efficiency of 83 kilograms per millimeter.

The demand for sugarcane is not governed by the sugar- energy sector , but by the consumer market, its way of life and its demand for food, energy, among other things. It is up to the sugar-energy sector to answer how this sugarcane will be produced and at what levels of efficiency and sustainability. As irrigated sugarcane uses less water to produce each ton of stalks, if the sugar-energy sector decides that it will produce 20, 40 or 60% of this annual production in an irrigated system, in the end, the need for water to meet the annual demand for cane will actually reduce.

For this, it would be essential to allocate irrigated production exclusively where there is water availability, available water. But the fact is that irrigated crops, even using water other than that which comes from rain, produce more and more efficiently. And in the final accounting, irrigated cane uses less water to produce the same ton of stalks or sugar.

Irrigated production, key to sustainability:
The irrigated sugarcane production system, like any other, must comply with the best sustainability practices and strictly comply with environmental legislation. This includes using only and exclusively licensed water. The grant is granted based on the study of the flow history of the source, ensuring that the largest fraction will remain intact, preserving the life of the ecosystem.

For this, responsible management of water resources by public bodies and the effective, cooperative and harmonious participation of users in basin committees is crucial. In this field, despite the great progress in recent years and the modern water legislation in Brazil, there is still a lot of opportunity for advancement.

For a technical and rational analysis of the sustainability of irrigated sugarcane production, it is essential to understand the following factors:
One) the amount of water used by all irrigated agriculture in the country represents less than 0.6% of what exists in our rivers;
Two) Brazil has one of the most modern water laws in the world;
Three) it is possible to make available for irrigated sugarcane production, in a sustainable way, a small fraction of the available flow still available in many regions of the country, and this only depends on technical and responsible management, focused on environmental sustainability;
Four) estimates point to the sustainable expansion capacity of irrigated production in Brazil for at least another 55 million hectares.
Five) irrigated production can be more efficient in the use of water than rainfed production.

We perceive, therefore, that the irrigated production of sugarcane is an opportunity for Brazil and the sugar-energy sector to reduce the amount of water used today to meet the demand for sugarcane, ethanol, and electricity, between others. Furthermore, the efficiency gain promoted by the irrigated production system implies verticalization of production, that is, greater production in a smaller area.

Thus, the amount of land needed to meet the demand for sugarcane could be substantially reduced, leaving land to be used for other uses, including the preservation of native vegetation. It is also worth emphasizing that straw biomass, root production and soil microbiological activity are proportional to the vigor of sugarcane aerial biomass production.

Therefore, soil cover and protection, erosion reduction, water infiltration, compaction reduction, soil microbiological activity and carbon sequestration are proportionally greater in rationally managed irrigated systems than in rainfed systems. For these reasons, production systems such as irrigated sugarcane, which are more modern, efficient, verticalized and rationally conducted, can provide greater environmental sustainability than rainfed production.

Increased sugarcane longevity:
The main factor for reducing productivity is associated with the loss of stalk population, which is the result, among other factors, of trampling, shaking and uprooting stumps, increased infestation of pests and diseases and degradation of soil fertility. The longevity of a sugarcane field is often defined by a minimum acceptable productivity. Sometimes this number is defined empirically.

In others, it's based on some financial metric. But, either empirically or through some financial criterion, in general, a minimum acceptable productivity range is always defined. In a plant with lower productivity levels, the ton of sugarcane per hectare could be 40 or 50. In the best sugarcane fields in the country, the minimum acceptable productivity of ton of sugarcane per hectare could be 80 or 90. However, all these references refer to an upland cane field.

If the same reference were maintained for irrigated areas, certainly the longevity of irrigated sugarcane fields would increase substantially because it would take longer for an irrigated sugarcane field to reach these low levels of productivity; due to the fact that it has better water and nutritional conditions at the time of regrowth. Therefore, it loses population at a slower rate than dryland sugarcane. The irrigated sugarcane field, in addition to maintaining a greater population of stalks, offers better conditions for the growth of stalks throughout the cycle.

Another important issue is that the greater water supply and better nutritional use of the irrigated sugarcane field allow it to compensate for any failures in the lines due to loss of population. That is, a one-meter failure in the irrigated sugarcane line has less weight in reducing productivity than the same meter in a non-irrigated area.

Considering the useful life of irrigation equipment, whether pivot or drip, it is possible to conduct two cycles of 8 to 10 years without major interventions on these equipment. Even in dripping, you can choose to change only the driplines at each cycle or after two cycles. The lateral lines (drip lines) represent approximately 30% of the cost of a new system and, with the exchange, it can operate for another two or three cycles.

Finally, compared to a rainfed system, it is a fact that the longevity of irrigated sugarcane fields is greater, reaching yields of around 100 to 120 tons per hectare between the twelfth and fifteenth cuts. For such results, however, it is not enough to add water to a rainfed production system.

Irrigated production has very different dynamics and practices from rainfed production. The mere addition of water to a rainfed system without adjustments in the choice of varieties, nutrition, phytosanitary treatments, maturation, logistics and other factors, will never allow extracting the potential of the irrigated system. Therefore, an irrigated production system is not limited to adding water to a rainfed system.

Production:
Control of the main production factor, water, allows the sugarcane field to extract its genetic potential and express all other improvements in excellent management. Without water, other practices are eroded and hardly ever fully meet expectations. When comparing a 12-year cycle, using Embrapa's recommendations for irrigated sugarcane production in the Cerrado, with little experience, the mills are able to deliver up to 69% more production in relation to the same area under rainfed conditions.

And as irrigated production manages to overcome the problems of the worst soil environments and the worst climate window (August to September), the plant can adopt the strategy of allocating its irrigated fraction in the worst environments and in the worst climate window, still obtaining expressive indirect gains for directing its best environments and climatic window to rainfed production.

Therefore, the biggest differential of adopting the irrigated system in a fraction of the plant's area is not the productivity of the irrigated area itself, but the verticalization of production as a whole, and the virtuous cycle that it brings in the efficiencies per ton of sugarcane produced or ground.

The verticalization of production reduces the demand for machinery and labor per ton, reduces the demand for area and the cost of reform to keep the plant full, reduces the demand for land, and a whole sequence of efficiency gains that culminate in the reduction cost (Capital Expenses and Operating Expenses) and demand for natural resources to produce each ton of sugarcane. For this reason, supporting part of the area of the plants with an irrigated system translates into the apex of excellence in agricultural management, competitiveness and sustainability of the Brazilian sugar-energy sector.