Paddy Soil Profile Distribution of δ~(13)C Subjected to Rice Straw Amendment and Burning

摘要

Paddy residues are the most generous agricultural biomass from the paddy cultivation, Paddy residues practices include crop residue amendment and in-situ burning. It indicated that residue amendment increased the organic carbon and nutrient contents in soil, However, an open residue burning is still a common practice in Thailand despite of strict law enforcements and proper education to farmers about its implications on soil, human and animal health The present study determined how residues management practices: residue amendment and stubble burning, influence the soil organic carbon by determining δ~(13)C in paddy soil profile. The 30 cm depth soil samples from the naturally straw amendment and stubble burning paddy fields were collected in Chiang Khwan district, Roi-et province during 2017. The δ~(13)C values with soil depth showed that residue management practices produce statistical differences in both soils. The δ~(13)C values of soil samples from amendment and burning sites ranged from -23.19‰ to -17.98‰ and -24.79‰ to -19.28‰, respectively. Carbon isotopes differentiate clearly between amendment site (more positive values) and burning site (more negative values). The results from this study were in accordance with literatures which reported that the δ~(13)C distribution in the soil profile can be applied to study in SOC dynamics as a result of different paddy residue management practices (amendment or burning). Further research is needed to confirm the validity of the stable carbon isotope technique in this type of studies.