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SUMMARY:Modelling and Assessing the Impacts of Intercropping\, as a Sustai
 nable Farming Practice\, on Food Security\, Air Quality\, and Public Healt
 h - Ka Ming Fung\, Graduate Division of Earth and Atmospheric Sciences\, T
 he Chinese University of Hong Kong
DTSTART:20190510T100000Z
DTEND:20190510T111500Z
UID:TALK123016@talks.cam.ac.uk
CONTACT:Paul Griffiths
DESCRIPTION:Agriculture is the major emitter of atmospheric ammonia (NH3) 
 in Europe\, China\, and the US (85 - 95%). This NH3 is also attributable t
 o approximately 20% of the fine particulate matter (PM2.5) formed\, which 
 harms human health in the neighbourhood areas. The fast-growing food produ
 ction\, due to the rising world population and their more meat-inclined di
 etary habits\, could thus worsen the pollution problem. Previous field stu
 dies have shown that soybean intercropping can exploit the mutualistic int
 eractions between crops to promote legume nitrogen fixation for enhancing 
 crop yield\, reducing fertiliser use\, and thus diminishing NH3 emission. 
 In this study\, we aim to investigate the potential benefit of large-scale
  intercropping on crop productivity\, air quality\, and public health. To 
 quantify crop yield and NH3 emission under intercropping\, we implement in
 to a soil biogeochemical model\, DeNitrification-DeComposition (DNDC)\, a 
 new scheme to parametrize the belowground interactions of intercropped cro
 ps. With the DNDC-simulated NH3 emission\, we predict the formation of dow
 nwind PM2.5 using a global 3-D chemical transport model\, GEOS-Chem. We fi
 nd that\, if all Chinese farms are adopting maize-soybean intercropping\, 
 the same croplands which were initially for only maize or soybean can now 
 produce both crops with comparable yields (90-100%) as their monoculture c
 ounterparts. The fertiliser use for intercropping is 42% lower\, leading t
 o a reduction in NH3 emission by 45% and a drop in PM2.5 concentration by 
 up to 2.3% (equivalent to 1.5 μg m-3). This improvement can spare the Chi
 nese government US$13 billion per year in air pollution-related health dam
 age costs. Toward a better understanding on how regional conversion to sus
 tainable farming alternatives may affect global climate and air quality\, 
 we are developing a process-based NH3 volatilisation scheme and the parame
 trisation of crop-crop belowground interactions into the Community Earth S
 ystem Model (CESM). We hope that our study can help policymakers to evalua
 te the costs and benefits of adopting sustainable alternatives and derive 
 a science-based long-term strategy for food security and air pollution mit
 igation.
LOCATION:Pfizer Lecture Theatre\, Department of Chemistry
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