An innovative proposal for the planting and cutting of sugarcane, the objective of which is to increase productivity in the field and reduce costs, is being developed at the National Laboratory of Bioethanol Science and Technology (CTBE) in Campinas, in inner-state São Paulo. This is a machine called a controlled traffic structure. It can carry out all the mechanized operations of the sugarcane farming cycle. The equipment manages to reach steep areas that today’s harvesters cannot.
“The mechanized harvesting operation as it is currently done basically uses the same technology as 50 years ago, which was developed in Australia,” says Professor Oscar Braunbeck, from the School of Agricultural Engineering (Feagri) at the State University of Campinas (Unicamp), coordinator of the controlled traffic farming program. One of the advantages of the new machinery, currently being tested in a laboratory that imitates the field conditions of a sugarcane plantation, is reducing traffic on the planted area and as a result soil compression, which is prejudicial to the growth of the plants in subsequent years.
While the controlled traffic farming machine has a gauge (distance between the wheels) of 9 meters, current harvesters have a gauge of between 1.6 and 2.4 meters. Because of this and their weight, they only manage to harvest one row of sugarcane at a time and cause compression of around 60% of the soil’s surface, which ends up harming the development of the crop. “Compression encourages erosion and makes it difficult for water to penetrate the soil,” says Braunbeck. The 40% of the land where current machinery is unable to go is the preserved area, on which sugarcane can be produced. “With a wider gauge the preserved area for planting would reach 87%,” is the comparison Braunbeck makes. “By reducing heavy traffic in sugar plantations we provide the opportunity for planting cane directly, as is done with cereals.”
The first version of the equipment was designed to adapt to the structure of current mechanization. So it was made in an articulated way, with traction and steering on all four wheels, arms that withdraw for road transport and harvesting heads that are positioned to cut six lines of cane, two at a time. It will be driven by an automatic pilot with GPS, which will be supervised by an operator.
The new machine will be able to go on to steeper ground. “Because the first version of the equipment we are developing is wider, it remains stable in places where the gradient is as great as 19%,” says Braunbeck. Today’s harvesters manage to go on land with a gradient no greater than 12%. “Above this, because they are narrow, they overturn fairly easily,” says the agricultural engineer Guilherme Ribeiro Gray, a former student at Feagri and one of the partners in Agricef, a company that is involved in the project.
Founded in 2005, until 2008 the company was housed in the Unicamp incubator, Incamp. Agricef has already had three projects approved under FAPESP’s Innovative Research in Small Companies (Pipe) type of funding, and since 2009 it has been participating in the CTBE project, in which it is responsible for the development of the harvesting module.
Braunbeck emphasizes that there has been no evolution in the sugarcane agricultural management system with the changes that have occurred in environmental, economic and social demands. Harvesting, for example, although it has undergone a great advance with the gradual prohibition of burning cane straw manually, still uses machinery developed in the 1950s in Australia. “The machines for harvesting cane have only undergone a few adaptations since they were first designed, while the harvesting of cereals has advanced a lot.”
It is right to focus on cereals. The area planted with cereals in the world is around 700 million hectares, while sugarcane occupies just 22 million hectares. “The loss during mechanical harvesting in sugar plantations today is around 10%,” says Gray. For comparison purposes, the loss in harvesting grain is around 1.5%. “To reduce damage in sugar plantations we’re proposing a principle that is different from the current one.” Instead of a harvester with a divider to separate the rows on the plantation, which results in tangling and a loss of cane, the basis of the proposed operation is to fix the cane in the machine to then cut it at its base, draw it in and move it by traction to the upper part, where it will be chopped up into small pieces and transferred to the trailer, a vehicle used for transporting the cane. “The separator that is on the sides of the equipment is synchronized with the speed at which the machine is moving,” says Gray. It raises the culm (stem) so the chain or moving-belt pulling mechanism can collect the cane. The idea is to handle the cane as little as possible before it is cut to reduce damage to the ratoon root system, which remains in the ground to regrow , and losses in the field.
Once the small cut up pieces of cane have been transferred to the trailer, the project proposes to load part of the straw onto it while the rest will remain as ground cover on the plantation. This cover will help reduce the temperature of the soil, control weeds and diminish water evaporation. Now, in most cases, all the straw is thrown onto the soil, because as its density is very low the cost of transport ends up being high. The proposal is for the straw to “hitch a ride” with the chopped up small pieces of cane so that it settles into the cracks between the cane. The main partner of the new machine project is Jacto, an agricultural machinery and electric vehicle industry headquartered in Pompeia, in inner-state São Paulo, with support from the Brazilian Development Bank (BNDES) in the amount of R$ 16 million. Within four years the equipment must be tested and functioning and the partner company has a further two years to make the product ready for sale.
The direct planting of cane, which takes place without plowing the soil, is one of the aspects of the project. “This is sustainable management, because every time the soil is plowed there is a loss, which will have an impact over the years,” says Braunbeck. The idea is that the machine opens up furrows in predefined places, where the sugarcane points will be evenly deposited in the correct amounts. Currently, the machines distribute them irregularly. “Distribution is very bad and more than 50% of the cuttings die because of competition among themselves.”
The CTBE also has a project for exploring precision farming to increase productivity and reduce fertilizer costs and environmental impact. The objective is to personalize soil management. Sensors will be developed in sugar plantations for measuring soil or plant properties. With information from the sensors, as the machinery moves around it would start treating the soil with the necessary inputs. An area of 100 hectares at the Pedra Mill in Serrana, in São Paulo State, is being used for trials. Other partners are the Brazilian Agricultural Research Corporation (Embrapa), Valtra, a manufacturer of tractors from Mogi das Cruzes, in São Paulo State, Paulista State University (Unesp) at Jaboticabal, Higher School of Agriculture “Luiz de Queiroz” of the University of São Paulo (USP) and Unicamp.
The studies that resulted in the agricultural machinery project started in the 1990s and extended over the subsequent years, when Braunbeck, with support from FAPESP, carried out basic research into the cutting and cleaning of sugarcane. Subsequently, other studies dealing with aspects of mechanized harvesting were carried out by Agricef’s partners, with guidance from Braunbeck. “All this knowledge formed the basis for the current project,” says the professor. In his assessment, the change from manual harvesting to mechanical has been very fast considering that sugarcane has been grown in Brazil for the last 500 years.
In the State of São Paulo, the main producer of Brazilian sugarcane , an agreement signed in 2007 between producers, mills and the government, called the Agro-environmental Protocol, determined the elimination of the burning of straw by 2014 in mechanized areas and by 2017 in all sugarcane-growing areas. In the rest of the country, the environmental legislation allows the burning of straw in sugar plantations until 2020.
“By converting from manual to mechanized harvesting there is a two-fold environmental gain,” says the researcher Marcelo Valadares Galdos, from the CTBE’s Sustainability Program, which is carrying out a full carbon audit of sugarcane ethanol in Brazil, a study carried out in partnership with Esalq. “On the one hand, when cane waste stops being burned we stop sending carbon dioxide into the atmosphere, but there are also other gases that contribute to the greenhouse effect and they are even more powerful, like nitrous oxide,” says Galdos.
The second gain is that by leaving the straw in the field, when it decomposes it ends up being incorporated into the land and there is an increase in the stock of carbon in the soil, which is very important for the ecosystem. “We’ve identified an average annual accumulation of 1,500 kg of carbon per hectare with the system without burning and leaving the straw on the ground,” adds Galdos. “There is between two and three times more carbon in a layer of up to 1 meter of soil than in all the vegetation.” Therefore, there is a reduction in greenhouse gas emissions. The particulate material, soot, was also computed in the audit. “This material goes into the atmosphere and has an effect that is related to global warming.”
1. Development of a mechanical aid for harvesting sugarcane without prior burning (nº 2004/14468-5); Modality Innovative Research in Small Companies (Pipe); Coordinator Efraim Albrecht Neto – Agricef; Investment R$ 430,251.88 (FAPESP)
2. Automated control of the synchronism between the sugarcane harvester and the cane trailer (nº 2006/56581-8); Modality Innovative Research in Small Companies (Pipe); Coordinator Rodrigo Fernando Galzerano Baldo – Agricef; Investment R$ 35,954.21 (FAPESP)
3. Implement attached to a tractor for harvesting sugarcane without prior burning (nº 2007/59163-5); Modality Innovative Research in Small Companies (Pipe); Coordinator Guilherme Ribeiro Gray – Agricef; Investment R$ 12,491.00 (FAPESP)
GALDOS, M.V. et al. Net greenhouse gas fluxes in Brazilian ethanol production systems. Global Change Biology Bioenergy. v 2. p. 37-44. 2010.