Previous water content influences the response of soil respiration to changes in water content in non-saline and saline soils
2014
Yan, N. | Marschner, P.
Three incubation experiments were carried out with a non-saline soil (electrical conductivity in a saturation paste (ECe) 1 dS m−1) to which NaCl was added to achieve ECe 10 and 30 dS m−1; pea straw was added at 20 g kg−1 as a nutrient source. Experiment 1 showed that cumulative respiration was highest in soil EC 1 and lowest in soil EC 30. The optimal water content for respiration was 60–70 % of WHC in all soils. There were two periods (days 1–7 and days 8–17) in Experiment 2. In the treatments with the same water content in both periods [optimal (O-O) and medium (M-M)], respiration rates decreased over time and were lower in M-M than in O-O. Cumulative respiration at medium water content did not differ between slow (L-SM) or rapid rewetting (L-RM) from low to medium water content. There were two periods in Experiment 3 with the water content in the first period 50, 40 or 30 % of WHC adjusted from 60 % during pre-incubation either slowly or rapidly. The water content in the second period was maintained or adjusted slowly to 30–60 %. Cumulative respiration differed between water contents but was not consistently different between rapid and slow drying in the first period. We conclude that the response of microbial activity to a certain water content is influenced by the previous water content whereas the speed at which the water content is adjusted had little effect on respiration at target water content.
Afficher plus [+] Moins [-]Nan Yan, Petra Marschner
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