NAR Local Dirt Physics: Sand Moisture (3%–20%) & Inversion Mechanics
NAR dirt circuits nationwide (Ohi, Kawasaki, Funabashi, Urawa, Sonoda, Saga, Kochi, Nagoya, Kasamatsu, Mombetsu, Morioka, Mizusawa, Kanazawa, Himeji) utilize deep natural sea sand. Unlike American dirt, moisture drastically alters surface density.
1%–5% Moisture: Dry & Deep Cushion (Stamina War)
Deep sand absorbs kinetic energy. Severe fatigue in the homestretch allows sweeping closers to reach frontrunners.
6%–14% Moisture: Yielding to Soft (Accelerated Speed)
Moisture binds the sand grains like wet beach sand. Surface firms up, track records tumble, and early pace leaders become tough to pass.
15%–20%+ Moisture: Sloppy / Standing Water (Speed Highway)
The track acts like an ice rink. Kickback becomes heavy mud, and horses hugging the inside rail wire the field over 75% of the time.