In Brazilian agriculture, maize ( Zea mays
L.) is prominent because of its magnitude of grain production. However, soil
compaction changes negatively the soil physical attributes, limiting the crop growth. This study aimed to evaluate physical
attributes of a clayey Oxisol (Rhodic Hapludox) under no-tillage, and the relationships between these attributes with maize
yield in the Midwest region of Brazil. Besides this, indicators of soil physical quality when subjected to levels of compaction
were determined. A randomized complete block design was applied with five replicates. Treatments were induced levels
of compaction: a reference condition that reflects 8 yr of no-tillage (NT); no-tillage with additional compaction by tractor
traffic in one (NT-1), two (NT-2), four (NT-4), and six passes (NT-6). There was significant correlation (P < 0.01) between
all physical attributes of the studied soil. Maize yield was positively correlated to macroporosity (r = 0.41*), and negatively
to penetration resistance (r = -0.42*), geometric mean diameter (r = -0.51*), and mean weighted diameter (r = -0.53*). The
index of emergence speed, stem diameter, plant height, grain mass, and grain yield decreased as soil compaction increased.
The physical attributes evaluated, especially the resistance to penetration and soil macroporosity, reveal the level of soil
compaction and can be used as soil physical quality indicators.