Abstract
The role of carbon pool of biochar as a method of long-term C sequestration in global warming mitigation is unclear. A two-year field study was conducted to investigate the seasonal variations of CO2 emissions from water-saving irrigation paddy fields in response to biochar amendment and irrigation patterns. Three biochar treatments under water-saving irrigation and one biochar treatment under flooding irrigation were studied, and the application rates were 0, 20, 40, and 40 t ha−1 and labeled as CI + NB (controlled irrigation and none biochar added), CI + MB (controlled irrigation and medium biochar added), CI + HB (controlled irrigation and high biochar added), and FI + HB (flood irrigation and high biochar added), respectively. Results showed that biochar application at medium rates (20 t ha−1) decreased CO2 emissions by 1.64–8.83% in rice paddy fields under water-saving irrigation, compared with the non-amendment treatment. However, the CO2 emissions from paddy fields increased by 4.39–5.43% in the CI + HB treatment, compared with CI + NB. Furthermore, the mean CO2 emissions from paddy fields under water-saving irrigation decreased by 2.22% compared with flood irrigation under the same amount of biochar application (40 t ha−1). Biochar amendment increased rice yield and water use efficiency by 9.35–36.30% and 15.1–42.5%, respectively, when combined with water-saving irrigation. The CO2 emissions were reduced in the CI + MB treatment, which then increased rice yield. The CO2 emissions from paddy fields were positively correlated with temperature. The highest value of the temperature sensitivity coefficient (Q10) was derived for the CI + MB treatment. The Q10 was higher under water-saving irrigation compared with flooding irrigation.
Highlights
The global scientific community has generally regarded the greenhouse effect as a major environmental concern
Applying moderate amounts of biochar reduced CO2 emissions in the paddy fields, whereas high contents of biomass biochar promoted CO2 emissions, which may be due to the upper limit of carbon sequestration function of biochar [14]
This study investigated the effects of different biochar application rates on CO2 emissions, rice yield and water use efficiency in paddy fields under water-saving irrigation
Summary
The global scientific community has generally regarded the greenhouse effect as a major environmental concern. The concentration of CO2 in the atmosphere has risen to the highest level in. The agroecosystem plays an important role in the budget, which account for 30%, of anthropogenic greenhouse gas (GHG) emissions [2]. As one of the world’s main land types, paddy fields in monsoonal Asia are considered significant contributors of GHG to the environment [3]. Rice planting areas account for approximately 26.4% of the total planting area in China, in which rice is one of the main grain crops. Further studies are necessary to identify the appropriate regulation of GHG emissions and emission reduction measures
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