Nitrous oxide emissions from soil amended with autoclaved lightweight aerated concrete (Alc) under different compaction and moisture Conditions

Abstract

Nitrous oxide (N2O) is one of the longest-lived greenhouse gases (GHGs) with a global warming potential which is 298 times higher than that of carbon dioxide. Different sources affect on GHGs emissions. Among them, soil physical conditions such as compaction and moisture content affect GHGs emissions from soil. Conditioners or amendments applied into soils may affect terrestrial N2O emissions. Autoclaved lightweight aerated concrete (ALC) is used as a soil amendment and conditioner. In this study, we examine the effects of soil compaction, moisture content, and ALC (Inenica, Clion Co., Ltd, Japan) addition on N2O emissions from soils. Laboratory experiments were conducted using a paddy soil amended with and without ALC (0% or 5%), under two levels of compaction (compacted and non-compacted), and two soil moisture contents (60% and 100% water holding capacity: WHC) in 200-mL glass bottles. All samples were incubated at 25°C for 21 days under aerobic conditions. Emissions of N2O were determined at 0, 1, 3-, 7-, 14- and 21-days using gas chromatography with thermal conductivity detector. Higher moisture content (100% WHC) and the addition of ALC significantly decreased N2O emissions. Soil compaction significantly increased N2O emissions from soil. The interaction between ALC addition with compaction and ALC addition with moisture content on cumulative N2O emissions was statistically significant (p<0.05). Results revealed that ALC addition suppressed the N2O emissions from soil, which was more effective at non-compacted and 100% WHC. Our study suggested implementing the precise dosage (5%) of ALC, along with an adequate moisture (100% WHC) and non-compacted conditions actively contribute the suppression of N2O emissions from soil while creating an ideal soil environment.