Rapid changes in carbon and phosphorus after rewetting of dry soil |
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| Authors: | Clayton R Butterly Ann M McNeill Jeff A Baldock Petra Marschner |
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| Institution: | (1) Department of Agricultural Sciences, La Trobe University, Kingsbury Drive, Melbourne, Victoria, 3086, Australia;(2) School of Agriculture Food and Wine, The University of Adelaide, Adelaide, South Australia, 5005, Australia;(3) CSIRO Land and Water, Glen Osmond, South Australia, 5064, Australia |
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| Abstract: | 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 (Presin) 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), Presin, DOP and DIP was immediate and greatest in the first 2 h. The Presin pulse was two to three times that measured by solution extraction (DIP). Also, Presin 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 Presin 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 Presin 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. |
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