Quick question from the field: in a loam under moderate dryness, how deep does a 10 mm irrigation set typically push the wetting front? I’ve got my rule-of-thumb answer from TDR snapshots at 5–20 cm, and I’m happy to walk through the quick way to estimate it for your fields.
I get about 7–10 cm in a moderately dry loam because ‘z ≈ depth_applied/Δθ’ and Δθ to field capacity is usually 0.10–0.15. @OP, a quick grav sample to pin down θi will tighten that estimate — call it about a credit card’s length of advance.