Evaluating soil quality in silvopastoral systems by the Soil Management Assessment Framework (SMAF) in the Colombian Amazon

Resumo

Monitoring the infl uence of livestock systems’ on soil quality (SQ) in the Colombian Amazon region is important
to ensure the sustainability of those agroecosystems. Here we used the Soil Management Assessment Framework (SMAF) to assess
the SQ responses to land-use change associated with the adoption of silvopastoral systems (SPS) at two study sites in the Colombian
Amazon region. A chronosequence formed by three land-use systems, refl ecting the typical land transition performed in the region, was
established at each study site: i) native vegetation (NV), ii) pasture (PAST), and iii) SPS. Soil samples were collected at 10 cm deep
increments until reaching 30 cm deep. Then soil pH, potassium, available phosphorus, microbial carbon, soil organic carbon, and bulk
density were measured. In addition, data from Visual Evaluation of Soil Structure (VESS) were correlated. Data were interpretated using
SMAF algorithms, and a Soil Quality Index (SQI) was calculated. Our data showed an SQ degradation due to land-use change from NV
to PAST, with soils reducing their capacity of soils function from 0.72 to 0.62. The establishment of SPS over extensive PAST restored
soil quality (SQI = 0.69) compared to PAST (both sites), even reaching similar SQI values to those observed in NV at site 1. The SMAF
showed to be a potential tool to monitor the SQ in low-fertility soils from the Colombian Amazon region. The VESS scores were also
correlated with SMAF - scores, proving to be a simple and complementary tool for farmers to monitor SQ in the Amazon region.