Ecological rice-cropping systems mitigate global warming - A meta-analysis

Geng Sun; Mei Sun; Linsen Du; Zhen Zhang; Zhichang Wang; Guangbin Zhang; San''an Nie; Huaqin Xu; Hua Wang

doi:10.1016/j.scitotenv.2021.147900

Ecological rice-cropping systems mitigate global warming - A meta-analysis

Sci Total Environ. 2021 Oct 1:789:147900. doi: 10.1016/j.scitotenv.2021.147900. Epub 2021 May 24.

Authors

Geng Sun¹, Mei Sun², Linsen Du³, Zhen Zhang³, Zhichang Wang³, Guangbin Zhang⁴, San''an Nie³, Huaqin Xu³, Hua Wang⁵

Affiliations

¹ College of Resources and Environment, Hunan Agricultural University, Changsha 410125, China; Soil and Fertilizer Institute, Hunan Academy of Agricultural Sciences, Changsha 410125, China.
² Soil and Fertilizer Institute, Hunan Academy of Agricultural Sciences, Changsha 410125, China.
³ College of Resources and Environment, Hunan Agricultural University, Changsha 410125, China.
⁴ State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academic Sciences, Nanjing 210008, China.
⁵ College of Resources and Environment, Hunan Agricultural University, Changsha 410125, China. Electronic address: wangchina926@hunau.edu.cn.

PMID: 34323843
DOI: 10.1016/j.scitotenv.2021.147900

Abstract

Ecological rice-cropping systems (ERSs) are prosperous rice ecosystems that have a profound influence on global greenhouse (GHG) effects. However, the high variation in research results requires an accurate evaluation of the ERS effects. In this study, three typical ERS modes, rice-crayfish, rice-duck, and rice-fish were selected, and a meta-analysis was conducted using the data of 34 studies to comprehensively evaluate the effects of ERSs on GHG emissions, the global warming potential (GWP), and GHG intensity (GHGI). The results showed that the ERSs reduced CH4 emissions significantly (-12.5%), but increased N2O emissions by 11.3% as compared with traditional rice-cropping systems (TRSs). Further, ERSs have slightly lower GWP, rice yield, and GHGI values (6.5%, 5.5%, and 5.6%, respectively) than TRSs. The rice-crayfish and rice-duck modes significantly alleviated the GWP by 18.0% and 11.1%, respectively, whereas the rice-fish mode enhanced the GWP by 20.8%. Moreover, the rice-duck mode significantly reduced the GHGI by 17.2%, while the ricecrayfish and rice-fish modes increased the GHGI by 9.7% and 8.8%, respectively. Further, the ERSs significantly changed the dissolved oxygen concentration in the flood water as well as the Eh, dissolved organic carbon, and ammonium nitrogen in the soil, wherein the effect sizes of the ERSs on the GHG emissions were significantly correlated with their respective increase. Considering the net ecosystem economic budget and CO2 emissions equivalent/output, ERSs were found to be effective "green technologies". Further, we found that the rice-duck ERS was a good ecological ricecropping system for global warming mitigation. Our study provided new ideas for sustainable agriculture.

Keywords: CO2 emissions equivalent/output; Ecological rice-cropping systems; Global greenhouse gas; Net ecosystem economic budget.