Response of soil respiration to dry-wet alternation in karst farmland
[Objective]The objective of this study is to explore the response of soil CO2 emission flux from calcareous soil to frequent dry-wet alternation in farmland of karst areas in southwest China.[Method]Taking calcareous soil in karst farmland as the research object,two dry-wet alternation intensities(simulated precipitation of 10 and 25 mm)were designed,with a dry-wet alternation cycle of 10 days as one cycle process,to investigate the response of soil respiration to dry-wet alternation in karst farmland.[Result]The intensity of dry-wet alternation significantly affected soil CO2 emission flux and total soil CO2 emissions(P＜0.05).Under two different dry-wet alternation intensities,soil CO2 emission flux reached its maximum shortly after water was applied,and then gradually decreased.For the 10 mm dry-wet alternation intensity,there was no significant difference between soil CO2 emission flux and total soil CO2 emissions under different cycles.However,for the 25 mm dry-wet alternation intensity,the difference between soil CO2 emission flux and total soil CO2 emissions under most cycles was significant(P＜0.05).Correlation analysis revealed that the correlation between soil water content and soil CO2 emission flux decreased continuously under the multiple cycles of dry-wet alternation.[Conclusion]The intensity and process of dry-wet alternation are important factors affecting soil respiration release in karst farmland.[Ch,5 fig.1 tab.64 ref.]
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