Comparative Study between Silvopastoral and Agroforest Systems on Soil Quality in a Disturbed Native Forest of South-Central Chile

Abstract

Agroforestry systems (AFSs) have gained recognition as a land use strategy to address food security and climate change. They involve intentionally cultivating trees alongside crops and/or animals. AFSs cover approximately 5% of the global forest area and promote sustainable soil conservation, including soil organic carbon (C) sequestration (CSEQ). In some areas of Chile, AFSs are used to preserve the ecological value of native forests. This study evaluates the effects of two AFSs, namely, an agroforest for fodder production (AGROFRST) and Silvopastoral (SPS), within a degraded native forest (Nothofagus obliqua sp.). The evaluation focuses on their impact on CSEQ capacity and soil quality (SQ), using soil quality indexes (SQIs) derived from 30 soil quality indicators (SINDs) related to physical, chemical, and microbiological properties at two depths (0–5 and 5–20 cm). The results for the total depth analyzed (0–20 cm) indicate an average CSEQ of 6.88 and 4.83 Mg C yr−1 and a global SQI of 37.8% and 31.0% for AGROFRST and SPS, respectively. Among the thirteen SINDs that demonstrated significant differences (p < 0.05), five were associated with the considered depths (P+, Ca2+, S, ECEC, and AlSAT), three differed between AGROFRST and SPS (BD, NH4+, NO3−), while SOC, K+, and Mg2+ varied across all conditions (e.g., combinations of systems and depths), and β-GLU and NMIN differed in a single condition. However, almost all 30 SINDs analyzed showed higher values at the 0–5 cm depth, indicating the positive effects of soil organic matter (SOM)/SOC additions. Significant interactions (Pearson’s correlation) revealed that SOC correlated with most SINDs (e.g., N, NH4+, P+, K+, Ca2+, Mg2+, S, ECEC, NMIN). These findings suggest that both AGROFRST and SPS systems have similar capabilities in restoring the ecological value of native Nothofagus forests while providing conditions for productive and complementary use. This sustainable option offers opportunities for cattle production alongside ecological restoration efforts and provides a possible strategy to generate public policies related to the ecosystem services of agroforestry systems.