Impacts of rice varieties and management on yield-scaled greenhouse gas emissions from rice fields in China: A meta-analysis

H Zheng,J Liu,H He,L Yao,J Tang,H Huang

doi:10.5194/bg-11-3685-2014

Abstract

Abstract. Increasing numbers of studies have suggested that a comprehensive assessment of the impacts of cropping practices on greenhouse gas (GHG) emissions per unit yield (yield-scaled), rather than by land area (area-scaled), is needed to inform trade-off decisions to increase yields and reduce GHG emissions. We conducted a meta-analysis to quantify impacts of rice varieties on the global warming potential (GWP) of GHG emissions at the yield scale in China. Our results showed that significantly higher yield-scaled GWP occurred with indica rice varieties (1101.72 kg CO2 equiv. Mg−1) than japonica rice varieties (711.38 kg CO2 equiv. Mg−1). Lower yield-scaled GHG emissions occurred within 120–130 days of growth duration after transplanting (GDAT; 613.66 kg CO2 equiv. Mg−1), followed by 90–100 days of GDAT (749.72 kg CO2 equiv. Mg−1, 100–110 days of GDAT (794.29 kg CO2 equiv. Mg−1), and 70–80 days of GDAT (800.85 kg CO2 equiv. Mg−1). The fertilizer rate of 150–200 kg N ha−1 resulted in the lowest yield-scaled GWP. Consequently, appropriate cultivar choice and pairs were of vital importance in the rice cropping system. A further life cycle assessment of GHG emissions among rice varieties at the yield scale is urgently needed to develop win–win policies for rice production to achieve higher yield with lower emissions.

Highlights

Agriculture is estimated to account for 10–12 % of anthropogenic emissions of greenhouse gases (GHG) worldwide, including 60 % of global nitrous oxide (N2O) emissions and 50 % of methane (CH4) emissions (Smith et al, 2007)
We aim to provide a new perspective to select rice varieties based on yield-scald GHG emissions within certain growth duration after transplanting to achieve higher yields with lower GHG emissions
Twenty-seven papers that included 120 data points were collected according to the following criteria: the measurement data must have been conducted under field conditions, CH4 and N2O fluxes must have been measured over an entire growth period of rice using the static chamber method, and both rice yield and GHG emissions had to be determined simultaneously

Summary

Introduction

Agriculture is estimated to account for 10–12 % of anthropogenic emissions of greenhouse gases (GHG) worldwide, including 60 % of global nitrous oxide (N2O) emissions and 50 % of methane (CH4) emissions (Smith et al, 2007). To ensure food security for its increasing population, Chinese rice production needs to increase by 20 % by 2030 (Peng et al, 2009). The increasing demand for rice in the future has raised tremendous concerns about increasing GHG emissions (van Beek et al, 2010; Zhang et al, 2011; van Groenigen et al, 2012). Information on trade-off between rice yield increases and GHG emission reductions is urgently needed to aid cropping technique innovation and policy selection. Area-based GHG emission information alone is not sufficient to assess the future trend of emissions under the context of increasing yields and the changing climate

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