A falha metabólica na agricultura brasileira: o caso dos fertilizantes sintéticos

Abstract

Sociometabolism refers to the set of material exchanges between humans and non-human nature. In capitalist societies, a metabolic rift disrupts the flows of matter and energy essential to ecosystems. Agriculture is a prime example of this disruption and represents the human activity with the greatest impact on the natural environment, including the very conditions and resources it depends on, such as soil. This study tests the metabolic rift hypothesis, which predicts that the growth rates of synthetic fertilizer use outpace the growth rates of agricultural productivity, indicating a degradation of soil fertility. As a result, increasing amounts of inputs are required to produce the same amount of food. We collected data on fertilizer application rates and the productivity of Brazil’s main crops—soybeans, corn, and sugarcane—which together account for over 70% of the country's farmland and are leading export commodities. We compared the slope coefficients of different growth trends using covariance analysis. On average, the growth rate of chemical fertilizer use was four times higher than the growth rate of agricultural productivity. Brazilian agriculture’s metabolic rift is degrading the local conditions it relies on, decreasing productivity, and deepening dependence on external inputs, making the system increasingly unsustainable. However, from the perspective of capital, this outcome is advantageous, as it drives greater dependency on external inputs and, consequently, an expanding consumer market for commodities. Low-interest financing, agricultural insurance, repeated debt forgiveness, and public subsidies have entrenched farmers' reliance on technological packages based on synthetic fertilizers, pesticides, and genetically modified seeds. Beyond the nutrients assessed here, we expect similar trends for other inputs, such as machinery and pesticides. Applying ecological principles to agricultural production, as proposed by the ecological intensification approach, can help mitigate these impacts. Nevertheless, a transformative change in agriculture is essential to overcoming the metabolic rift, ensuring food security, and protecting the environment.