Objetivou-se mensurar economicamente os custos internos da área de produção de soja no cerrado piauiense, sob os sistemas de plantio direto e convencional, causados pelo processo de erosão, nas safras de 2000/2001 e de 2007/2008. O procedimento metodológico centrou-se no levantamento bibliográfico e estatístico de dados secundários e na aplicação do método do custo de reposição de nutrientes, no intuito de verificar qual o impacto econômico da degradação do solo na região. Por meio da pesquisa constatou-se que, em ambos os períodos de safras e sistemas de plantios analisados, os custos de reposição foram expressivos, representando, em média, 2,9% do valor total da produção de soja. Na safra 2000/2001, os custos por hectare foram de R$ 22,96 e R$ 21,93 para os plantios convencional e direto, respectivamente. Para a safra 2007/2008, os custos foram de R$ 22,40 e R$ 21,20, respectivamente. Portanto, esta configuração explicitou a relativa estabilidade do valor da perda de solo no período de análise, haja vista apresentar reduzido decréscimo na safra 2007/2008. Logo, inferiu-se que o uso do sistema de plantio direto no cultivo de soja no cerrado piauiense não somente proporcionou vantagens econômicas, mas, sobretudo, contribuiu para a sustentabilidade do agroecossistema.

The present article aimed to measure the economic costs of the domestic production soybean area in the cerrado (one type of vegetation in Brazil) of Piauí, in the systems of conventional and tillage, caused by the process of erosion in the 2000/2001 and 2007/2008 seasons. It analyzes the historical process of international integration of the Brazilian economy through the primary-exporting model, emphasizing the intensive use of natural resources as factor of competitiveness, characterized by the occupation and use of Brazilian cerrado and based on the soybean production and examined the consequences and risks to the biome arising from that process. The methodological procedure focused on the literature review and statistical from secondary data and the application of the replacement cost of nutrients method, to verify the economic impact of soil degradation in the region. Through the research, it was found that in both periods of crop and planting systems analyzed, costs of replacement were significant, representing, on average, 2.9 percent of the total soybean production. In the 2000/2001 season, the cost per hectare was 22.96 reais and 21.93 reais for conventional tillage and direct planting, respectively. While in the 2007/2008 crop, harvest costs were 22.40 reais and 21.20 reais, respectively. Therefore, this configuration explained the relative stability of the value of the loss of land during the period under review, once having presented low decrease in the 2007/2008 season. Therefore, it is inferred that the use of the system of tillage in the soybean planting in the cerrado of Piauí not only has economic advantages, but above all, has contributed to the sustainability of the agro ecosystem.

Analisou-se a forma como a soja, implantada no cerrado piauiense, influencia os eixos ambiental e socioeconômico.O baixo valor da terra, a proximidade do mercado externo, solos mecanizáveis, os recursos governamentais facilitados na forma de incentivos fiscais e financeiros são fatores que justificam a exploração dessa região.Conclui-se que o uso e ocupação agrícola dessa região seguem o mesmo receituário desenvolvimentista ocorrido no Cerrado do Brasil.

This is a study on the way the soybean, which was introduced in Piauí Savanna, has influenced the environmental and social-economic axis. The factors that explained Piauí's land exploitation were: the low price of its agricultural land, its proximity to the external market, the viable mechanization of its soils, and governmental resources facilitated by financial and fiscal incentives. Therefore, the use and the agricultural exploitation of that region have followed the same developmental pattern of the Brazilian savanna.