The enzyme reaction was carried out on acidified NaOH 0.5 N soil extracts diluted 10 times and incubated for 0 or 30 min. Detection range is 2–10 nmol of glucose-6-P in the well of a microplate containing 50 μl of sample and 50 μl of master mix. The total P of the samples was obtained after a digestion process with 12 N HCl (v/v) at 110 °C for 16 h