Adenosine 5'-triphosphate and adenylate energy charge in waterlogged soil

Abstract

Changes in adenosine 5'-triphosphate (ATP) were monitored during aerobic and anaerobic incubation of three paddy soils from Konosu, Japan, and three freely-draining soils from Rothamsted, England, two under arable cultivation and one under grass. Little change in ATP content occurred when any of the soils were incubated aerobically. In contrast, ATP contents decreased sharply on anaerobic incubation of the Rothamsted grassland and arable soils, falling to less than 10% of the original levels after 80 days. ATP contents also decreased when the Konosu paddy soils were incubated anerobically, but the decrease was more gradual, to 21–38% of the original levels after 80 days. The “half-life” of ATP in soil under anaerobic conditions was thus much less in the three Rothamsted soils (15–18 days) than in the three paddy soils (39–59 days). ATP contents increased rapidly when the anaerobically-incubated soils were aerated: thus aeration increased the ATP content of one soil from 2.5 to 4.0 nmol ATP g −1 soil within 10 min. The adenylate energy charge (AEC) decreased during anaerobic incubation, falling in the grassland soil from 0.76 to 0.34, and in one of the paddy soils from 0.75 to 0.54. The AEC increased rapidly when these anaerobically-incubated soils were subsequently aerated, but never regained its pre-anaerobic value. Adenosine 5'-monophosphate (AMP) contents increased during anaerobic incubation but decreased again during a subsequent aeration. These results show that the soil microbial biomass, when stressed by exposure to anaerobic conditions, cannot maintain its ATP content and AEC level at the customary values for moist aerobic soils, just as has been shown earlier for organisms stressed by air-drying.