Establishment of Climate-smart Rice-Wheat Rotation Cropping system

Food security is an important issue for all countries around the world, especially when food production has been challenged under climate change. The food self-sufficiency ratio of Taiwan is around only 33 % weighted by energy in 2013, with importing excessive cereal grains as a serious threat to Taiwan. Also, there is about 10 % artificially greenhouse gas emission generating from agriculture production. Therefore, it is suggested to mitigate the environmental impacts from agriculture production system and increase the degree of food self-sufficiency ratio of Taiwan. Rice-wheat rotation is a possible innovative cropping system for Taiwan, which integrate with the upland-lowland rotation, wheat production and labor saving. In the present study the analysis of environmental impacts of rice-wheat rotation system was performed by the tool of life cycle assessment and hot spots of the impacts for the cropping system were determined. This study is aim to establish a local climate-smart cropping system which is high yield, high quality, energy saving, food production and eco-friendly. In the study, a two-year rice-wheat rotation experiments at TDARES (Taichung District Agriculture Research and Extension Station) and Daya (Taichung) since 2012 winter was conducted. The system boundary of life cycle assessment consisted of production of farm inputs (such as fertilizer, pesticide and seed), tillage, irrigation, farming practice and post-harvesting, and used the function unit as kg grain and per hectare in evaluating the environment impacts from crop production. In this study we selected energy consumption, global warming potential, acidification, and eutrophication as environmental impact items to evaluate rice-wheat system. According to the research results, the main environment impact came from field emission and the variation was up to 50 %. In each crop, the GWP (Global warming potential) was 3~53 tg CO2 eq /ha and 1.3~10 kg CO2 eq/ kg grain. Although field emission was the main hot-spot, it still could be improved by modified fertilizer management. In this study, fertilizer adjustment was the most effective way to mitigate the field emission, while other adjusted strategies such as tillage and second crop period fallow didn’t show consistent mitigation effects. But there is still some positive effect of non-tillage and changing crop residue retention ratio has been confirmed in several long-term field research. In all, minimum tillage and suitable fertilizer management seemed to be the suitable practice for establishing climate-smart rice-wheat rotation system.