Single farming systems (SFS) such as monocultures may negatively affect soil structural
quality. This study tested the hypothesis that integrated farming systems (IFS), i.e., the
combination of cropping and forestry and/or livestock farming, improves soil structural
quality, root development and soil organic carbon. An experimental area was set up in
2012 at the Canguiri experimental farm belonging to the Federal University of Paraná,
Southern Brazil. The soils are predominantly Ferralsols. The experimental treatments
representing different farming systems, organized in a random block design with three
replicates, were: Forestry (F), Conventional Crop Production (C), Livestock (L), and integrated
Crop-Forestry (CF), Crop-Livestock (CL), Livestock-Forestry (LF), and Crop-Livestock-
Forestry (CLF). In situ measurements and sampling were carried out in the 0–0.3m layer
during summer 2019/20, and included soil penetration resistance (PR), soil structural quality
based on visual evaluation of soil structure (SqVESS scores), root length (RL), root volume (RV)
and soil organic carbon content (SOC). Soil structural quality, penetration resistance, root
length and volume, and SOC varied between farming systems, but no significant differences
were found between single (C, L, F) and integrated farming systems (CF, CL, LF, CLF). The
single system Forestry (F) and the integrated systems including forestry (LF, CF, CLF) tended
to have higher SqVESS scores, i.e. poorer soil structural quality, and higher PR, which we
associate with the generally drier soil conditions that are due to higher soil water uptake and
higher interception and reduce the frequency of wetting-drying cycles. Roots were
concentrated in the shallow soil layer (0–0.1m depth), and this was especially
pronounced in the Crop (C) single farming system. Based on the measured values, our
results suggest an acceptable soil structural quality in all farming systems. Our data revealed
strong, significant relationships between soil structural quality, penetration resistance, root
growth and SOC, demonstrating that improvements in soil structure results in lower soil
penetration resistance, higher root volumes and higher SOC, and vice versa. Soil PR was
positively correlated with SqVESS (R2 = 0.84), indicating that better soil structural quality
resulted in lower soil mechanical resistance. This, in turn, increased root length and volume,
which increases carbon input to soil and therefore increases SOC in the long run.