Glucose Addition

After 58 days of incubation, a solution containing 15 mg of glucose per gram of soil carbon was added to a 5-g (fresh wt) subsample of each soil, with the corresponding volume (1 cm³) of distilled water added to a further 5-g subsample [13]. All solution was directly added to the soil surface in each of the 96 bottles containing incubated cores using a 10 cc syringe with a needle tip.

During incubation, the soil cores were maintained at the designated WHC by weighing the bottles every 2 days and adding the correct amount of deionized water over the incubation experiment. Deionized water reservoirs were maintained in each incubator to allow the water additions to be made at the correct temperature. The intact cores were broken up, passed through a 1 mm sieve, and roots and stones removed at the end of the incubation. The roots and stones were oven-dried at 65°C and weighed. All sieved samples were oven-dried at 105°C to calculate the dry weight of soil in each sample.