Rapid changes in carbon and phosphorus after rewetting of dry soil

Drying rewetting (DRW) cycles are important for soil organic matter turnover; however, few studies have considered the short-term effects on nutrient availability. The pulses in soil respiration, extractable C, P and N pools were quantified after a single DRW cycle (ten sampling times over 49 h). Soil was pre-incubated with or without glucose (2.5 g kg(-1)) for 10 days to induce differences in the size and activity of the microflora and then either subjected to a single DRW cycle (7-day drying period) or kept constantly moist. A resin extractable P resin, 1 method was used and compared to extraction of dissolved organic (DOP) and inorganic P (DIP) with a salt solution. The pulse in soil respiration, extractable organic C (EOC), P(resim) DOP and DIP was immediate and greatest in the first 2 h. The P(resin) pulse was two to three times that measured by solution extraction (DIP). Also, P(resin) quantified temporal changes in P not apparent in DIP, indicating the advantage of anion-exchange membranes in quantifying short-term changes in P availability. The P(resin) pulse was smaller in the soil incubated with glucose showing that P pulses will be quantitatively smaller in a soil with an active microbial biomass. In contrast to P. pre-incubation with glucose did not alter EOC concentration or the pulse in EOC after rewetting. The P(resin) pulse had disappeared by 49 h after DRW despite continued elevated rates of respiration. The sustained increase in DIP following DRW may have implications for plant availability or environmental losses.