Physical Quality of a Chromic Luvisol Under Agroforestry Systems.

Land use in agroforestry systems (AFS) in semi-arid regions has numerous environmental benefits, such as the preservation of plant species, cycling of nutrients, reduction in erosion and protection of water sources, among others. This study aimed to evaluate the degree of compaction and compressive behaviour of a Chromic Luvisol after 14 years of use in agrosilvopastoral (AGP) and silvopastoral (SILV) systems, and under natural vegetation (NV). Five samples of disturbed and undisturbed soil were collected at a depth of 0-5 cm in order to assess the degree of compaction (DC), compression index (Cc), preconsolidation pressure (σp), maximum density (D_SMax), critical moisture (U_crit) and stocks of total organic carbon (E_Toc), light organic matter (E_Lom), light organic matter carbon (E_Clom) and light organic matter nitrogen (E_Nlom) in the soil. Means comparison between the usage systems was carried out by t-test at 5, 10 and 20% probability. The results showed that the AFS increased the D_SMax (p<0.05), and reduced the U_crit (p<0.05) and E_Nlom (p<0:10), which suggests a change in the quality of the organic matter in the soil by the AFS (<E_Nlom), having no effect however on σp (p>0.20). No significant differences were seen between DC averages for AGP, SILV or NV, respectively 80, 81 and 83%. Implementing the AFS did not promote any changes that could compromise the pore space. After 14 years, the compressive behavior of soils under AFS is characterised by the absence of any increase in the degree of soil compaction or in the load-bearing capacity of the soils, and their being suitable for plant development.