Soil CO2-C Emissions and Correlations with Soil Properties in Degraded and Managed Pastures in Southern Brazil

Land degradation has been a global environmental issue, and its cause includes poorly managed grazing. Quantitative information is needed to support policy actions for food and water security and development. The objective of this study was to assess and characterize CO2-C emissions in degraded (DP) and managed pasture (MP) areas located close to one another, describing their spatial-temporal variability and any correlation with possible controlling factors. A grid of 100x100m with 102 sample points in each area was set up. Measurements of CO2-C emission (FCO2), soil temperature (T-soil), soil water content (WCsoil), soil physical (i.e. soil texture, soil bulk density, macro-porosity, micro-porosity, air-filled pore space and total pore volume) and chemical (i.e. pH, calcium, magnesium, phosphorus, potassium and cation exchange capacity) analysis were conducted at each sample point. Total emissions calculated from the area below the FCO2 graphs were 640.7 and 440.0kg CO2-Cha(-1) in the DP and MP, respectively. Soil temperature in the MP was lower (t-test, p<0.01) throughout the experimental period when compared with the DP. This study found that the degraded pasture area released significantly more CO2-C compared with the well-managed pasture. Therefore, the introduction of best management practices in pasture areas is an important strategy to reduce soil CO2-C losses and promote soil C accumulation. The MP presented lower FCO2 despite its higher soil C stock, indicating a more stable soil C condition when compared with the DP area. Copyright (c) 2016 John Wiley & Sons, Ltd.