Helping China's crop production sustainably face the challenges of tomorrow

With rising temperatures and an increasing frequency in extreme events, climate change was suggested to adversely impact crop yields, thereby threatening the needs of a growing world population. At the same time, the expansion and intensification of crop production to meet the increasing demand are likely to boost greenhouse gas emissions, further exacerbating climate change. As the country with the largest population on the planet and a proportionately limited surface of arable land, China is especially exposed to the risks associated with this vicious circle. Using the past to achieve a strong future, Dr. Xuhui Wang is developing a model to study the Chinese production and greenhouse gas emission of major croplands (wheat, maize and rice) and their responses to global change factors, including extreme climatic events, under various management practices. How did extreme climatic events impact crop production? What impact did various land management practices have – for instance irrigation, fertilisation or specific crop rotation? What was the impact on greenhouse gas emissions? By providing answers to these vital questions, the CHINA-CROP project aims to give insight into the vulnerability of cropland production under climate extremes and to single out the most sensitive regions. The objective of the model simulations is to provide the necessary understanding for the identification of promising strategies to ensure the productivity and sustainability of crop production in the future.

"Global population is expected to double by the middle of the century. To ensure food security, projections lay down the need to increase food production by 70 %, or even more", reports Dr. Xuhui Wang. "The problem is that croplands already exist everywhere, amounting to approximately 20% of global land surface. If we further increase the cropland areas, it will have to come from forests or grasslands, which has adverse consequences on the climate, the environment and biodiversity." "Our best and only solution is thus to increase production on the existing crop fields," the researcher explains. "But this is quite a challenge because we need to do that without copiously increasing green gas emissions and worsening climate change." Current methods used for accelerated production include increasing crop seasons, increasing irrigation, extensive use of fertilisers and the development of new crop varieties with more potential for productivity. "These methods have proved very efficient in the past, but under the increasing strain of global warming and rising food demand, their current technological potential will soon be exhausted", Dr. Xuhui Wang stresses. "Moreover, the widespread use of fertilizers excessively contributes to greenhouse gas emissions, hence worsening climate change and putting humans, biodiversity and the planet at risk".

Testing the efficacy and the sustainability of various management practices under climate change conditions

The objective of the CHINA-CROP project will be to quantify and understand how climate change and the different ways in which land was managed over the last 40 years have impacted crop production and green gas emissions. To complete the model, Dr. Xuhui Wang is building on ORCHIDEE-CROP, a model he developed during his PhD to simulate the energy and carbon budgets of croplands. Adapting it to the specificities of the Chinese crops and incorporating data about relevant land management practices, the researcher and his team will then be able to recreate the evolution of crop yields and greenhouse gas emissions over the course of the last 40 years and analyse fluctuations in regard to climate and management changes. This way, the simulations may reveal possible combination of management options capable of ensuring food security without excessively increasing greenhouse gas emissions.

The outcome of the project will contribute to the next Intergovernmental Panel on Climate Change assessment reports and provide quantitative evidences for the development of agricultural strategies to adapt and mitigate the impacts of climate change. But can a reasonable compromise be found to increase productivity without aggravating climate change? "A balance will be hard to reach and there is much uncertainty", Dr. Xuhui Wang says. "The growth of crop production has stabilized in many of the major food producing countries. Current techniques are reaching their limit, but new technologies are currently being developed to boost production and help soften the environmental impact". With the CHINA-CROP project, Dr. Xuhui Wang will greatly contribute to drawing up a complete assessment of Chinese cropland agriculture, bringing to light the worst and best practices and paving the way for new promising ones.