Short-term soil physical quality improvements promoted by an agroforestry system

摘要

Concerns with environmental sustainability have promoted adoption of conservationist practices in agricultural production, mainly focused on soil quality preservation or recovery. The aim of this study was evaluating short-term soil physical quality improvements under agroforestry system management in Southern Brazil. The agroforestry system was implemented in 2013 in an Ultisol with Sandy Loam texture. Rows of agroforestry system (AFS-R) were composed by biomass producer trees intercalated with wood and fruit producer trees while in the inter-rows (AFS-IR) perennial sub-shrub, perennial grass, and summer and winter green manure annual species were implanted. Soil under native forest was used as control. Soil samples in the 0.0-0.1; 0.1-0.2 and 0.2-0.4 m depths were collected for the determination of physical attributes and the total organic carbon content in 2015, 2016 and 2017. Bulk density decreased about 9% (AFS-R) and 6% (AFS-IR) in 0.0-0.1 m between 2015 and 2017. Total porosity increased over time only in AFS-R, at a rate of 0.025 m(3)m(-3)year(-1). The total organic carbon content of AFS increased over time only in the 0.0-0.1 m layer, although remained up to 35% less in relation to the native forest. The agroforestry system resulted in consistent improvements of several soil physical attributes over short time, particularly in rows with arboreal plants, highlighting the role of diversified tree root systems and plant residues accumulation, which implied a rapid improvement in soil quality. In this context, long-term studies with agroforestry systems are crucial to understand the benefits on soil quality.