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Agronomy QUESTION #2085
Question 1
Subsoiling (deep tillage with a chisel or paraplow) is specifically recommended when:
  • Surface soil bulk density exceeds 1.0 g/cm³
  • A compacted pan or hardpan layer exists at 25–45 cm depth with bulk density > 1.6–1.8 g/cm³ for loam soils, restricting root penetration, water infiltration, and drainage — disrupting this layer can dramatically improve yield on affected soils✔️
  • Annual plowing at 15–20 cm depth is performed regularly
  • The soil surface needs refinement before sowing small-seeded crops
Correct Answer Explanation
Subsoiling targets tillage pans created by repeated tillage at the same depth (plow pan) or traffic compaction (traffic pan). These layers have bulk density > 1.6–1.8 g/cm³ (loam), restricting root growth, water movement, and drainage. Chisel plows or paraglows fracture these layers at 35–60 cm depth without inverting the soil profile. Benefits last 3–5 years depending on traffic management.