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Título

SMAF IN TEMPERATE AND SUBTROPICAL AGROECOSYSTEMS: A COMPARATIVE ANALYSIS

Resumo

The Soil Management Assessment Framework (SMAF) was initially developed to assess soil health as affected by management practices in US agroecosystems. In recent years, SMAF has been used in Brazil to assess the impacts of conservation practices and land use changes in soil health, yet the sensitivity of SMAF scoring functions and their relationship with ecosystem services is not proven for tropical and subtropical regions. Here, we assessed SMAF soil quality indices (SQI) in agroecosystems in Brazil and Mid-South US, and investigated the ability of SMAF to differentiate between conservation and conventional management practices and the relationship of SMAF with ecosystem services. For this, we compiled peer-reviewed SMAF studies published in Brazil (n = 206) and compared to studies published for the Mid-South US (n = 142). The Kruskal-Wallis test was used to compare soil indicators [pH, P, K, bulk density (BD), aggregate stability, soil organic C (SOC), and microbial biomass C (MBC)] and SMAF SQI between conservation and conventional agricultural practices in each region. Linear regressions were performed to assess the relationship between SMAF SQI and SOC retention. Mean SMAF SQI values varied between 59-77% and 57-72% in conservation and conventional agroecosystems in Brazil, respectively, and between 63-86% and 62-86% in conservation and conventional agroecosystems in the Mid-Southern US, respectively. Despite the overall lower BD and higher SOC contents in conservation agroecosystems, SMAF SQI did not differ between conservation and conventional systems across soil depths and in both regions (p > 0.05). Yet, coefficients of determination (R2) between 0.50-0.65 suggest that SMAF SQI can be used as an indicator of SOC retention and relates to the ability of agroecosystems to provide ecosystem services. The SMAF scoring functions need to be revised to effectively capture the benefits of conservation practices on soil health in subtropical and tropical systems. 

Palavras-chave

soil health, ecosystem services, conservation agriculture

Agradecimentos

Dr. Marcio Nunes (University of Florida, Gainsville) for the insights