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P.S.(Mar 2014): During teardown, sensor depths were noted as 5, 3, 2 cm for near, far, flr, respectively, not just our usual 5cm at all sites. Since I only sampled 0–6 cm here, we can't look for any depth variation. However, we could expect that far and flr would read drier than near, as did occur. I don't know if 2 and 3cm are shallow enough to have suffered from lack-of-depth effects.