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Purpose Bio-based recycling systems and agricultural production using recycled materials are often evaluated separately. This study performs an environmental and socio-economic life cycle assessment (LCA) of a food waste treatment and spinach farming system in Japan. The environmental and economic tradeoffs of introducing a recycling system and the net environmental benefit of the substitution of market fertilizer considering operation changes are also examined. Methods Three scenarios were developed and compared. In the conventional (CV) scenario, food waste is collected, incinerated, and disposed of in landfill, and the farmer uses market organic fertilizer. The on-site composting (OC) scenario processes food waste using an on-site garbage disposer and transports compost to a nearby spinach farmer. Food waste in the centralized composting (CC) scenario is transported to a centralized composting facility and resultant compost is sent to the farm. Primary data were obtained from field experiments and interviews. Non-greenhouse gas (GHG) emissions from the field and nitrogen leaching to water systems were simulated using the denitrification-decomposition (DNDC) model. The environmental LCA targeted climate change, eutrophication, and waste landfill. An input-output analysis estimated socio-economic indicators, namely gross added value and employment inducement effect. Results and discussionThe scenario with the lowest impact is the CC scenario. Climate change and eutrophication impacts are highest in the OC scenario and waste landfill impacts are most significant in the CV scenario. The weighted impact by LIME2 can be reduced by 47% in the CC scenario and 17% in the OC scenario due to the recycling of food waste instead of dumping in the landfill. The difference in socio-economic indicators between the scenarios was relatively small, although the CV scenario encouraged more employment. The substitution effect of composting, as well as the environmental impact reduction of replacing market organic fertilizer with compost, will result in 28.7% of the avoided impacts in GHG emissions. Conclusions Both composting scenarios are feasible from an environmental and socio-economic perspective when compared with conventional organic production, although there is a tradeoff between waste landfill and GHG emissions for the on-site composting system. However, the OC scenario needs to save electricity to improve its environmental competitiveness with the CV scenario. When considering the substitution effect of composting, it is recommended to take into account that agricultural operation also changes.

The shortage of labor is one of the major challenges facing agriculture in Japan. Technological innovations are required to overcome the limitations of the workload per worker. One such innovation is smart agriculture, which utilizes advanced technologies such as robots, AI, and IoT. This study aimed to provide data on the workload and pest control costs for the development of sustainable agriculture. The cost of pest control was compared between a boom sprayer, power sprayer, and unmanned aerial vehicles (UAVs) for two model rice farmers. The Ovako Working Posture Analysis System (OWAS) and metabolic equivalent (METs) were used to measure workloads while using UAVs. The labor cost was reduced to half with the usage of UAVs compared with conventional machines. The resulting METs, or physical activity during pest-control work using UAVs, could be lower than those when using pest control machines. Through OWAS, 63.86% of the total jobs using UAVs were identified as having a low risk of musculoskeletal injury. The results suggest that UAVs could compensate for the shortage of workers, and these are effective tools to support the expansion of the agricultural area.

Existing research shows that lifestyle changes and sustainable consumption play an important role in global warming mitigation. One way to alter consumer behavior and make it more environmentally responsible is to enhance communication between all stakeholders, that is, producers, retailers, and consumers. This paper evaluates the GHG reduction potential of changing daily shopping behavior through behavioral transformation. Behaviorally transformative actions in this context cover select foods and daily necessities, and are analyzed here from a life cycle assessment perspective. We developed multiple product selection scenarios to evaluate GHG emissions related to the purchase of daily commodities. Based on life cycle assessment, we estimated GHG emissions from production and distribution both in terms of current product selection and possible improved selection. Among other results, our study shows that due to seasonal consumption and energy conversion, greenhouse fruits and vegetables have high potential to reduce GHG emission. The GHG reduction potential of each individual commodity is not high because daily commodities consist of a number of goods. However, combinations of various actions can achieve a high reduction potential.