Management opportunities to mitigate greenhouse gas emissions from Chinese agriculture

Abstract

Agriculture accounts for approximately 11% of China?s national greenhouse gas (GHG) emissions. Through adoption of region-specific best management practices, Chinese farmers can contribute to emission reduction while maintaining food security for its large population (>1300 Million). This paper presents the outcome of a bottom?up assessment to quantify technical potential of mitigation measures for Chinese agriculture using meta-analysis of data from 240 publications for cropland, 67 publications for grassland and 139 publications for livestock, and provides the reference scenario for the cost analysis of identified mitigation measures. Management options with greatest mitigation potential for rice, or rice-based cropping systems are conservation tillage, controlled irrigation; replacement of urea with ammonium sulphate, nitrogen (N) inhibitor application, reduced N fertilizer application, integrated rice-fish-duck farming and biochar application. A 15% reduction in current average synthetic N fertilizer application for rice in China i.e., 231 kg N ha?1, would result in 12% decrease in direct soil nitrous oxide (N2O) emissions. Combined application of chemical and organic fertilizer, conservation tillage, biochar application and reduced N application are possible measures that can reduce overall GHG emissions from upland cropping systems. Conventional fertilizer inputs for greenhouse vegetables are more than 2?8 times the optimal crop nutrient demand. A 20?40% reduction in N fertilizer application to vegetable crops can reduce N2O emissions by 32?121%, while not negatively impacting the yield. One of the most important mitigation measures for agricultural grasslands could be conversion of low yielding cropland, particularly on slopes, to shrub land or grassland, which is also a promising option to decrease soil erosion. In addition, grazing exclusion and reduced grazing intensity can increase SOC sequestration and decrease overall emissions while improving the largely degraded grasslands. For livestock production, where poor quality forage is commonly fed, improving grazing management and diet quality can reduce methane (CH4) emissions by 11% and 5%, on average. Dietary supplements can reduce CH4 emissions further, with lipids (15% reduction) and tannins or saponins (11% reduction) showing the greatest potential. We also suggest the most economically cost-effective mitigation measures, drawing on related work on the construction of marginal abatement cost curves for the sector.authorsversionPeer reviewe

Greenhouse gas mitigation potential in crop production with biochar soil amendment—a carbon footprint assessment for cross‐site field experiments from China

“…While the yield-scaled N 2 O emissions were reduced by 31% or 17%, the CH 4 emissions were enhanced largely by 93% or 195% under manure or straw application which induced the increases in yield-scaled GWP by 54% and 154% (Feng et al, 2013). Nayak et al (2015) further found that application of N inhibitor or slow release N could mitigate N 2 O emission by 0.01-0.66 t CO 2 -eq ha −1 but had no effect on SOC pool. These indicated that BSA had the integrated benefit of CH 4 and N 2 O reductions, which was superior to other agricultural practices, especially other kinds of organic matter addition.…”

“…In rice paddies, biochar amendment both lowered the yield-scaled CH 4 and N 2 O emissions by 26% and 16%, respectively. The application of N inhibitor or slow release N could also both mitigate the CH 4 and N 2 O emissions by 0.35 and 0.51 t CO 2 -eq ha −1 in paddy rice production of China conclude by a meta-analysis using nearly 50 published field studies (Nayak et al, 2015), which could be compared to the CH 4 and N 2 O emissions F I G U R E 3 Greenhouse gas emission change by biochar soil amendment with the scenarios mitigation being 2.05 and 0.13 t CO 2 -eq ha −1 under BSA by this study. While the yield-scaled N 2 O emissions were reduced by 31% or 17%, the CH 4 emissions were enhanced largely by 93% or 195% under manure or straw application which induced the increases in yield-scaled GWP by 54% and 154% (Feng et al, 2013).…”

Mitigating effects of ex situ application of rice straw on CH4 and N2O emissions from paddy-upland coexisting system

“…A few studies have reported that transferring surplus rice straw from paddy system to upland system is an effective practice to improve organic matter, fertility, and productivity of upland soils58. Some studies investigated the in situ rice straw management on GHG emissions, and found that straw mulching, straw off-season application and straw-derived biochar application could decrease the GWP compared with the incorporation of fresh straw into soil1718192021. However, the effectiveness of rice straw ex situ application on mitigation of CH 4 and N 2 O has not been studied yet.…”

Sustainable intensification of China's agriculture: the key role of nutrient management and climate change mitigation and adaptation

“…Some 80% of the environmental damage arises directly from or is related to N and P mismanagement in the crop and livestock sectors. On the other hand there are many cost-effective opportunities for correcting nutrient mismanagement, and particularly through better manure management (Chadwick et al, 2015;Jia et al, 2015); improved N fertilizer management (Hofmeir et al, 2015;Zhang et al, 2015); more holistic resource management (Nayak et al, 2015) and closer policy integration.…”