1. Soil respiration and nutrient availability after heating are influenced by salinity but not by prior drying and rewetting
- Author
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Petra Marschner and Mihiri Seneviratne
- Subjects
0303 health sciences ,Residue (complex analysis) ,Chemistry ,Amendment ,Soil Science ,04 agricultural and veterinary sciences ,Microbiology ,Salinity ,Soil respiration ,03 medical and health sciences ,Animal science ,Nutrient ,Soil water ,Respiration ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Water treatment ,Agronomy and Crop Science ,030304 developmental biology - Abstract
Semi-arid and arid regions are characterised by drying and rewetting events, salinity as well as fires. The effects of these stresses on soils are all related to water availability and have been investigated extensively, but usually separately. To study the impact of two stresses, we combined a short heating event as it may occur in fast-moving grass fires with either a drying and rewetting event or salinity. In the first experiment, soils were incubated air-dried, moderately dried and constantly moist for 7 days after which the dried soils were rewetted. Seven days after rewetting, half of the replicates from each treatment were heated and then maintained at 60 °C for 30 min followed by rapid rewetting, while others remained unheated. The rewetting flush of respiration after 7 days was greater in previously air-dried soil than moderately dry soil. Regardless of prior water treatment, heating followed by rewetting compared to constantly moist soil increased respiration threefold and available N and P by about 20–30%. In the second experiment, NaCl was added to non-saline soil (EC1:5 0.01 dS m−1) to achieve EC1:5 1 and 4 ds m−1 (referred to as NS, S1 and S4). Soils were incubated moist for 1 month and then amended with pea residue at 10 g kg−1. Five days after residue amendment, half of the replicates from each treatment were heated and rewetted as in the first experiment. In unheated S4 compared to NS, cumulative respiration was 30% lower and available N and P were threefold and 30% higher. Heating reduced cumulative respiration by 10% in NS and S1 but by 30% in S4. Compared to unheated treatments, available N in heated NS was up to tenfold higher, but in S4, heating increased available N only up to threefold. In all salinity treatments, heating increased available P by about 15%. It can be concluded that the impact of short-term heating on nutrient availability and soil respiration was not affected by prior drying and rewetting. High salinity on the other hand reduced the impact on nutrient availability whereas the effect on soil respiration was exacerbated compared to non-saline soil.
- Published
- 2020
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