SOIL ORGANIC C IN LATOSSOLOS_RS_BRAZIL

Approximately 5% of the total Brazilian GHG emissions (0.11 Gt CO₂ and GWP-AR5) originate in the Planalto of Rio Grande do Sul state (RS), a representative agricultural region in Southern Brazil. This study aimed to assess SOCS (soil organic C stocks) in Oxisols (Latossolos) of the Planalto, with up-to-date data obtained from recent field campaigns and legacy data, and relate these SOC stocks to environmental variables. A literature search identified 195 documents with SOCS in layers 0-30 cm and 0-100 cm. The mean SOCS (0-30 cm) in the Latossolos was significantly higher (73,6 Mg ha^-1) than the suggested IPCC default (55 Mg ha^-1). The highest stocks (237 ±39 Mg ha^-1) were measured in uncultivated Latossolos Brunos in the 0-100 cm layer. The most frequently occurring soil Latossolo Vermelho distroférrico-LVdf (25% of the Planalto), also had high SOCS. Surprisingly Latossolos Vermelho Distrófico (LVd) also had high SOCS, in spite of the coarser texture. The estimated SOCS in Latosoolos of the Planalto is 419,9 Tg C, 36% larger than reported previous studies. We concluded that, despite significant land use changes, soils of this region maintain large SOCS which had been underestimated in previous studies.