Cow Dung-Based Superabsorbent Polymers as Water-Retaining Amendments of Soils

Persistent dry conditions have significantly affected agricultural productivity, while also posing a threat to food security. To alleviate the effects of aridity, superabsorbent polymers have been widely used to improve soil water retention and increase drought tolerance in the soil recently. However, most of their raw materials originate from petroleum-based materials, which raises concerns about their biodegradability and environmental effect. This study focuses on creating cow dung-based superabsorbent polymers (CDSP) with excellent swelling capacities, achieving up to 494 g/g at solubilization equilibrium due to its porous properties and excellent water affinity. After five cycles, the swelling ratio of the group with better performance remained at nearly 300 g/g. The water retention capacity of the soil amended with CDSP increased by 1-3 times compared to the original, with the duration of water retention extending from 51 h to 72-120 h. More interestingly, CDSP improved soil pore structure and plant drought resistance, extending the survival time of plant under water deficit and increasing fresh plant weight by up to 2.6 times. These findings demonstrated the CDSP as a potential soil enhancer and a solution to climate-induced drought challenge, showing their effectiveness in sustainable agricultural development and waste resource utilization.