Drying-Wetting Cycles: Effect on Deep Soil Carbon

Author： Qi Ji Markewitz Daniel Foroughi Maryam Jokela Eric Strahm Brian Vogel Jason

Publisher： MDPI

E-ISSN： 2571-8789|2|1|3-3

ISSN： 2571-8789

Source： Soil Systems, Vol.2, Iss.1, 2018-01, pp. : 3-3

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

In the Southeast United States (U.S.), the climate is predicted to be warmer and have more severe drought in the summer. Decreasing rainfall in summer months should create more severe soil drying, which will eventually affect re-wetting cycles deeper in the soil profile. Changing drying-wetting cycles in this deeper portion of the profile may impact the soil C pool, the largest pool of terrestrial C globally. The aim of this research is to study the effect of drying-wetting cycles on deep soil C. A soil incubation experiment was established using four soils that are part of a simulated drought experiment in Oklahoma, Virginia, Georgia, and Florida. Soils were incubated from as many as eight layers up to a depth of 3.0 m. During incubations, soil respiration was generally greatest in surface soils and declined with depth. When compared to soils that were kept constantly moist, drying-wetting cycles did not consistently stimulate more soil respiration. Soil respiration as a proportion of total soil C, however, was higher in soils below 1 m than above. Total C (R² = 0.82) and hydrolysable C (R² = 0.77) were the best predictors for soil respiration. Assuming that there was no other factor (i.e., new carbon inputs) affecting soil respiration at depth other than soil moisture cycles, this study indicates that there would be no significant change to soil respiration in deep soils under more severe drying-wetting cycles.