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Protected land

In the Amazon a cultivation technique takes advantage of brushwood instead of burning it

Illustration Braz/Reproduction Miguel BoyayanAt least once a month biologists Elisa Vieira Wandelli, from Embrapa Amazônia Ocidental (Embrapa Western Amazon) and Sandra Celia Tapia-Coral, from the National Research Institute of the Amazônia (Inpa), visit six farming families living on a settlement close to Manaus. They are monitoring the introduction of tipitamba, an agricultural crop-growing technique that substitutes the burning of brushwood, secondary vegetation that grows on cleared and abandoned areas, by making advantageous use of it. In the most recent version of this methodology a tractor grinds up trees that are up to 20 cm in diameter, leaving the cut-up leaves and wood on the ground behind it. Then men following after spread the covering evenly, which will protect the soil from the erosion, intense heat and nutrient loss that would be inevitable if the vegetation were burned.

This technique, which has already been adopted by a hundred families of small farmers in six states in the Amazon, began being developed in 1991 in Pará by a group of Brazilian and German researchers. They were looking for an alternative to farming based on the slashing and burning of natural vegetation that is used by 600,000 families to produce 70% of the food eaten in the Amazon, but that is of limited efficiency: productivity is only good for up to two years, until the vegetation that survived the fire grows back again. In addition to reducing soil fertility, this traditional form of agriculture contributes to the destruction of the original forest when new land for growing crops is in short supply, and is one of the reasons why 200 million hectares of already cleared land in the Amazon have been abandoned.

The first attempts at cutting, chopping up and reusing the vegetation manually proved not to be productive but indicated the way that led to mechanization and the current methods. Today, the agricultural and environmental benefits of the methodology developed by the teams coordinated by agronomist Osvaldo Ryohei Kato, from Embrapa Eastern Amazon in Belém, and biologist Manfred Denich, from the University of Bonn, in a project initially called Human Impact Studies on Forests and Areas that Flood in the Tropics (Shift),  are clear. When the vegetation is chopped up and returned to the soil it is transformed into a slowly released fertilizer that supplies phosphorous, nitrogen and potassium to the plants as it decomposes. Kato, the son of Japanese immigrants who was born and grew up on pepper plantations in Tomé-Açu, in northeast Para, says that soil covered with chopped-up vegetation delays by at least four months having to remove the invading grasses that fight for space and nutrients with farm crops and that appear more quickly when the vegetation is burned.

Rice, salad vegetables and fruit – Experiments carried out over the last few years indicate that rice, corn, beans and cassava can grow in soil treated in this way. “Families can grow two successive crops in the same area instead of just one, since they no longer need to leave the soil to recover as they do with burning”, says Kato. Furthermore, he says that the land can be prepared at any time of the year and so the agricultural calendar that determines what to plant in each month becomes more elastic. According to Kato, tests carried out by the farmers have shown that “tipitamba” can be used also in growing salad vegetables and fruit, like soursop, assai, cupuassu, muricy, oranges, cashews and passion fruit.

Tipitamba is not only an alternative to the burning that is responsible for  75% of Brazilian emissions of gases that contribute to global warming, one of the causes of climate change. Supported by the German government, by the National Council for Scientific and Technological Development (CNPq) and by the Pará government (more recently by the Ministry of the Environment and Banco da Amazônia) this technique is also a way of taking advantage of brushwood. Although seen only as temporary vegetation in a space undergoing transformation, brushwood occupies 76% of the 3.4 million hectares of the north region that was classified as unused but useful land in the Agricultural and Livestock Farming Census of 1995, the most recent.

The use of growing techniques like tipitamba could help save the image of this area of native vegetation from being considered as idle land or a “brushwood reserve”, an expression used by economist Francisco de Assis Costa, a professor at the Center for High Amazonian Studies (Naea) at the Federal University of Pará (UFPA), in a recent study. With time it could also eliminate the other meaning that Costa uses, of “scrap brushwood” or “waste brushwood” – abandoned and unproductive areas that according to him express “the failure of the original vegetation”, the forest, or the traditional and economically inefficient agriculture and livestock farming. A less aggressive cropping technique might also reinforce what he calls “brushwood capital”, when the vegetation becomes a productive element or a  means of production, like a machine for producing nitrogen, phosphorous and other nutrients that are necessary for agricultural crops.

The possibility of periodically reusing forest vegetation is gaining supporters as the barriers come down. Biologist Flavio Luizão and his team from Inpa were afraid that as the brushwood rotted it would release an unacceptable amount of methane, one of the gases responsible for global warming. His experiments in the LBA Project (Large Scale Biosphere-Atmosphere Experiment in the Amazon) have shown, however, that as wood rots it releases less methane, not more. For Luizao the result suggests that methane is possibly being incorporated by micro-organisms and insects that break down the leaves and branches, since this type of biodiversity becomes more abundant, as Sandra Tapia-Coral saw. According to the biologist when the soil is covered with chopped-up vegetation it is more porous and water, micro and macro-organisms and oxygen can therefore circulate more easily, creating an atmosphere that absorbs methane. “We saw no adverse effects in this methodology”, says Luizão. This year Eric Davidson, from Woods Hole Research Center in the United States, along with Kato and other researchers from Embrapa Eastern Amazon, showed in the journal, Global Change Biology, that cutting and chopping up vegetation emits less methane right after planting and absorbs more in the subsequent months than the traditional technique of slashing and burning the natural vegetation. Another conclusion of this study is that tipitamba also emits five times less of the other gases that are responsible for global warming.

There are still adjustments to be made to tipitamba, a word from the Tyrios Indians of Pará, meaning “brushwood” or “former tilled ground”. The first is the cost of equipment, since the cost of a tractor is around R$ 200,000 and the chopper, some R$ 100,000. The machines that come from Germany are a stronger version of the prototypes brought in in 2000 for tests; they are used in Central Europe to chop up smaller and less tough branches. Costs are not so onerous, however, if the equipment is bought through cooperatives or companies, as Alumínio do Brasil (Albrás) did when it bought a tractor-chopper to encourage 20 families to cultivate the land around its plant in Barcarena in Pará without burning. In one of the chapters of the book, Innovation and spreading technology for the sustainability of family farming in the Amazon – Results and implications of the Social-economic Shift Project, organized by Costa, Thomas Hurtienne and Claudia Kahwage (full version free on Google Books), Geraldo Stachetti Rodrigues and other researchers from Embrapa show that environmental services like carbon capture, which would give farmers a comparative advantage over those who release carbon dioxide by burning the forest, could extend the economic efficiency of this technique.

Another problem to be solved is that of productivity in the first year of cultivation, which although it is greater than on burned land is still considered low. “It’s the same problem as direct planting on straw”, remembers Silas Aquino de Souza, from Embrapa Western Amazon in Manaus. Because of this Luizão defends the idea that farmers should receive a subsidy to be able to get them through this initial phase. Productivity begins to increase as from the second year, thereby reducing or even eliminating the need for additional nutrients. “Our hypothesis”, says Kato, “is that the quality of the soil improves in the long term as a result of the accumulation of decaying organic material”.

One hurdle has been overcome: convincing farmers to change their land cultivation habits. In 2000, with a prototype chopper, the researchers were able to interest six farming families in the project in Igaparé-Açu and five in Marapanim, in Pará. During his Masters degree course at the Federal University of Para and in Embrapa Eastern Amazon, Carlos Oliveira monitored the families from Marapanim and concluded that the users appropriated the technology more easily when they were involved with its development from the outset. Over time the families themselves began to propose and carry out experiments for using this technique when growing water melons, pepper or salad vegetables. Today, one hundred families have adapted tipitamba to suit their crops and land in Acre, Amapá, Amazonas, Rondônia, Roraima and Maranhão, with the support of the Embrapa units in these states. “We just offer the innovation”, says Kato. “It’s the farmers who decide how to use it and today they’re the ones who are teaching us what can or cannot be planted using this technique.”