Alleviating Heat Stress and Water Scarcity in Cultivation with Biodegradable Radiative Cooling Mulch

Agriculture faces pressing challenges of heat stress and water scarcity due to climate change. While mulching is a common solution, traditional mulching materials lack sub-ambient cooling capabilities and biodegradability, resulting in elevated soil temperature, increased moisture evaporation, exacerbated global agricultural heat-water crisis, and soil microplastics pollution. Herein, we have developed a biodegradable and biocompatible ethyl-cellulose radiative cooling mulch with a solar reflectance and thermal emissivity of 97% and 0.93, respectively, to provide zero-energy cooling for soil surfaces. Field tests have demonstrated that the radiative cooling mulch significantly reduces soil moisture evaporation by 60% through cooling soil surfaces, while also improves plant growth by 30% through reducing crop leaf temperature and increasing sunlight exposure for photosynthesis in hot days. Moreover, global heat-water nexus simulations show that the mulch increases soil moisture preservation by over 80% and alleviates agricultural water scarcity by over 60% in arid regions during hot seasons. The work offers an eco-friendly and feasible pathway to foster sustainable agriculture by alleviating heat stress and water scarcity in the context of global warming.