Dados do Trabalho

Título

SOIL CARBON CHANGES AFTER INTRODUCTION OF INTEGRATED PRODUCTION SYSTEMS IN THE SEMIARID REGION OF MINAS GERAIS STATE

Resumo

Agrosilvopastoral or integrated crop–livestock–forest (ICLF) systems integrate crops, livestock, and forests in the same area, with an observed interaction and synergy between these components. This production system model has the potential to promote CO2 sequestration from the atmosphere and accumulate more soil organic C in depth than conventional agricultural systems. As we have limited studies that evaluate the soil C dynamics in agrosilvopastoral systems to understand its origin, using the 13C isotope natural abundance technique, the aim of this study was to evaluate the soil C stocks in a chronosequence of land use in a transition area between the Cerrado and Caatinga biomes. The experimental field site was located at the Barra Farm, in the municipality of Francisco Sá, Minas Gerais State, Brazil. The chronosequence of land use was composed by Native Vegetation, Nominal Pasture and two ICLF systems. Two soil samplings (four and six years after ICLF introduction) was performed in each evaluated system at 0–5, 5–10, 10–20, 20–30, and 30–40 cm depths to evaluate the soil carbon stocks and natural 13C abundance. We found no differences in soil C stocks among the evaluated systems. However, comparing the results between the two years of evaluation, significant increase in soil C was observed, with an annual accumulation rate of 1.44, 2.17 and 2.8 Mg ha-1 year-1 respectively for ICLF1, ICLF2 and Nominal Pasture. The δ13C negative values in ICLF1 and ICLF2 systems increased in depth due the higher proportion of C remaining from the native vegetation and introduced by the eucalyptus species than that from the annual C4 photosynthetic cycle (sorghum and Marandu grass). Nominal Pasture showed a higher enrichment of 13C in the topsoil. Our findings showed that integrated systems can increase soil carbon stocks when introduced in a transitional area between Cerrado and Caatinga biomes. Long-term studies are needed to confirm whether this increase will continue over time.

Palavras-chave

13C, Integrated crop-livestock-forest system, Soil organic matter

Instituição financiadora

FAPEMIG, CNPq, CAPES and BAYER S.A.

Agradecimentos

Barra Farm and Center of Nuclear Energy in Agriculture (CENA)