Soil Respiration Measurements: A Comparison between Soda Lime Technique and LI-8iooA Automated Soil CO2 Flux System

Abstract

Soil respiration (Rs) is one of the major pools in the global carbon cycle. However, there are uncertainties in quantifying Rs rates, partly because of the differences in methods of quantifying this pool. This study compares two widely used methods for measurement of Rs rates, the static closed chamber (SCC) (soda lime) and the automated dynamic closed chamber (DCC) (LI-81ooA automated soil CO2 flux system). Soda lime (SL) results were compared against LI-8iooA automated soil CO2 flux system with the use of continuous long-term chamber (LTC) measurement and survey chamber (SC) techniques. Effects of soil temperature and soil moisture on Rs rates were also assessed. Results showed that Rs rates measured with SL are in good agreement with the LTC (R2 = 0.78) and SC (R2 = 0.59) techniques. The SL technique, however, underestimated Rs by about 23% compared with SC (p < 0.001, n = 574) and about 2o% to 29% compared with LTC (p<o.00i, n = 48). Rs rates and soil temperature demonstrated strong relationship (R2 = 0.56, 0.64, 0.71), but not with the soil moisture (R2 = 0.38). The soil temperature provides a lot of information about Rs rates; hence, a useful variable in Rs modelling. The derived discrepancy values between the two methods of Rs measurements are useful information that could be used to adjust the values of Rs rates measured with the SL technique.