Carbon sequestration in an agroforestry system of coffee with rubber trees compared to open-grown coffee in southern Brazil

Abstract

Evidences of climate change and global warming have induced an increasing interest in quantifying carbon stocks in biomass and soil. The cultivation of coffee in agroforestry systems (AF) is more sustainable and can enhance the potential of carbon fixation, making this system a good alternative to help mitigate global warming. In this study the carbon stocks in the biomass and soil were determined in an agroforestry system of coffee with rubber trees in Londrina, PR, southern Brazil, in a 16-year-old plantation where coffee was spaced at 2.5 × 0.80 m and rubber trees were planted in double rows of 4.0 × 2.5 m which were separated by 16 m. These were then compared to open-grown coffee. The experimental design followed was a randomized block with four replications. The above and below ground biomasses were determined separately by the destructive method. Soil samples were collected at layers up to 0.70 m depth. Carbon was determined by the dry combustion method. The results showed an increase in the carbon fixation in the agroforestry system compared to the open-grown coffee. Considering the carbon in the biomass and in the soil up to 0.70 m, the open-grown coffee presented an average of 148.34 Mg ha−1, while the AF had 195.6 Mg ha−1. The average coffee production from seven harvests in the AF was similar to the open-grown, with additional income provided by the tapping of the rubber trees. It is concluded that the agroforestry system of coffee with rubber trees in double rows has a good potential of carbon fixation in southern Brazil.