Sustainable Cotton Production Systems for the Humid Savannas of Central Brazil

Sustainable cotton production systems for the humid savannas of central Brazil L. Séguy1, S. Bouzinac1, J.L. Belot2, J.Martin2. 1CIRAD-CA, Cropping systems program,, in partnership with USP/CENA (Piracicaba SP, Brazil), Goiânia GO BRAZIL 2CIRAD-CA, Cotton program in partnership with COODETEC, Cascavel BRAZIL Correspondence author [email protected] Sustainable cotton production systems for the humid savannas of central Brazil ABSTRACT ferralitic soils formed on basaltic rock in the south to the less fertile yellow-red and yellow-grey ferralitic soils formed on acid rock in the humid savannas (Figure 1). Most Brazilian cotton is produced in the Cerrados, i.e. the humid savannas of Central Brazil. In this This transfer of the cotton crop has, in reality, frontier region, a very dynamic and powerful agri- been a shift from the subtropical zone with a high po- culture is driven by the search for short term eco- tential for productivity, but which was greatly limited by nomic returns despite the absence of subsidies. the continuous practice of tillage and monoculture lead- Highly mechanized farmers first introduced large- ing to the degradation of the soil’s physical and biological properties (Figure 2; Séguy et al., 1998, 1997- scale monocultures dominated by soybean. More 2002) towards the wet tropical region where the soil is recently, cotton has become an attractive cash less fertile but where, over the last seven to ten years, crop, despite difficult natural and economic con- land has been farmed using Direct seeding Mulch based ditions, resulting in irregular returns. Furthermore, Cropping systems (DMC). These farming systems are the domination of monocultures, the use of disc based on successions of two crops per year, including tillage and high levels of inputs have resulted in soybean or rainfed rice as main crops and maize, sorghum or millet as second crops (called “safrinhas”). soil and environmental degradation and less sus- With these successions, managed without tillage, the tainable production systems. CIRAD, Brazilian re- soil is totally protected from erosion and develops ex- search institutes, and various private partners cellent physical and biological properties, which are (Maeda, Coodetec, Agronorte) have joined forces extremely favourable for cotton growth (Séguy et al., to find solutions resulting in significant and regu- 1998, 2001a). lar decreases in production costs while preserving soil fertility and the environment. Crop rotations, Research and development direct seeding under cover crops, and varietal test- methodology ing within the most performing cropping systems, The “cerrados”: a huge land using a participatory approach, constitute the most The “cerrados”: a huge land promising avenues to achieve these objectives. This reserve for agricultural method, known as innovation-extension, allows the development The savannah of the Brazilian humid tropical zone best producers to reach yields ranging from 3000 (HTZ), called “cerrados”, covers about 200 million hect- to more than 5000 kg/ha of seed cotton, while ares of which about half could be used for agricultural constantly increasing fiber quality, reducing pro- production (Figure 1). Currently only 50 million are duction costs and risks and minimising the impact actually used, essentially for pastures (80%). In the state on the environment. of Mato Grosso, these lands were brought under culti- vation in the late ‘70s under conventional tillage and Introduction soybean monoculture, rapidly leading to severe soil degradation because of erosive processes and exces- sive mineralisation of the soil’s organic matter. Between The Brazilian cotton belt has shifted towards the 1986 and 2002, in order to answer rapidly and effi- humid tropics. At the beginning of the 1990s, the states ciently to this failure, CIRAD and its research and de- of the central south (Paraná, São Paulo, Goiás and velopment partners created, developed and progres- Minas Gerais) produced 540000 tons of fiber or 81% sively disseminated more and more efficient DMC. of the Brazilian production, the state of Paraná alone supplying 52% of national production (source: CONAB). At the same period, the state of Mato Grosso produced Building up innovation with a only 37000 tons or 5,5% of national production. participatory on-farm approach The development of DMC in developing coun- Over the past four years (1998-2002), the pan- tries, and more recently in Europe (South-North trans- orama of cotton production has been radically transfer), is based on a participatory innovation-extension formed (source: CONAB). The state of Mato Grosso methodology (Séguy et al., 1998, 2001a). The assess- has become Brazil’s number one producer with 427000 ment of a farmer’s current cropping systems is taken tons of fiber in 2002 or 53% of national production. as a starting point on which to build new operational The majority of cotton production has thus shifted from systems (conception and modelling phase), which are southern regions with a subtropical climate (annual then implemented at full scale (adaptation and valida- pluviometry ranging between 1000-1600 mm) to the tion phase). Well-modelled and implemented cropping humid tropical zone (higher pluviometry ranging from systems provide a good support for process-based re- 1300 mm to more than 2000 mm concentrated in a search in order to understand the differences of their shorter period of seven to eight months). This also in- functioning. The scientific research, which must first and volved a move from predominantly fertile dark-red foremost be useful, is thus connected to today’s agri- 482 World Cotton Research Conference-3 2003 Cape Town - South Africa cultural realities in order to provide farmers with suit- (responsible for ramulosis). Calcio-magnesium lime is able systems for tomorrow (Figure 3). also incorporated every two or three years jointly with cotton residues. The soil is finally pulverized by a disk This in situ research, called “innovation-exten- harrow to incorporate the cover crop seeds sown broad- sion-training” (Séguy et al., 1998, 2001a) uses a few cast at the beginning of the rainy season (mainly mil- experimental units and a net of regional reference let, sometimes sorghum). This system known as “semi farms. On the experimental units, jointly managed by direct seeding” momentarily re-exposes the soil to ero- researchers and farmers, the cropping systems are sion, accelerates the mineralisation of soil organic car- organised in a matrix on toposequences representing bon (S.O.C.) indicating annual C losses, brings back the physical environment (soil types and their state of to the soil surface weed seeds allowing them to com- degradation, dominant weeds, etc.). On the reference pete with cotton, and favours the development of nema- farms, influential and charismatic voluntary producers todes. Furthermore, large quantities of fertilizers (150 implement the systems they have selected in the ex- to 160 kg/ha N + 180 to 200 kg/ha P205 + 200 to perimental units, adapting them if need be; the group 260 kg/ha K20) and agrochemicals are used (in order of reference farms is representative of regional vari- to face increasing parasitic pressure by pests and cryp- ability (physical and socio-economic environment). togamic diseases), resulting in very high production costs, ranging from 1300 to 1600 US $/ha, which is Starting from traditional cropping systems, the superior to land prices. In a region placed at a disad- new systems are elaborated through the progressive, vantage by the long distances from seaports and the organised and monitored incorporation of more com- precarious state of transport infrastructures, economic petitive factors of production. The setting up of matri- risks linked to cotton production become considerable ces meets precise criteria, which allow the interpreta- (Figure 5). tion of the effects, both instant and cumulative, of the systems’ components in the course of time. Both the New diversified and sustainable matrices and the reference farms are places of action, DMC are available from research innovation and training where the agricultural models In HTZ, between 1986 and 2002, taking as a of the past, the present and the future are brought to- starting point for their research the initial degrading gether. They constitute a valuable monitoring labora- system of soybean monoculture with tillage, CIRAD and tory for more process-based scientific research and a its Brazilian partners have successively developed: breeding ground for the creation of diversified farming • Systems of two-year rotations with soybean and systems (from DMC restricted to grain and fiber pro- cereals (rice, maize) as annual single crops, with duction to farming systems including cattle and forestry tillage; productions). • Systems of two-year rotations with “safrinhas” every two years, that is with the introduction every other Results and Discussion year of a second crop in succession to the main crop, implemented in direct seeding on the resi- Current cotton management dues of the main crop; practices are not sustainable • Systems with two annual crops per year (main crop In Mato Grosso, farmers and extension agents + second crop) entirely implemented in direct seed- implemented cotton crops by adapting part of the re- ing without tillage; sults of the previous research carried out by CIRAD • Systems with three annual crops per year ; the main between 1994 and 1999 in the less rainy regions of crop (soybean or rice or maize) is followed

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