Atmospheric water irrigation and plant growth promotion in sandy soil by polyacrylamide-chitosan-CaCl₂ aerogels

Water scarcity is the main cause of desertification in arid regions. Atmospheric water harvesting (AWH) technology represents the most promising solution to this problem. In this study, a polyacrylamide-chitosan matrix loaded with CaCl₂ (PAM-CS-CaCl₂) was designed to absorb moisture and was applied to a sandy soil to increase the soil water content. The results showed that the water absorption rate of the PAM-CS-CaCl₂ aerogel was as high as 3.76 g/g at 90 % RH and 25 °C. Sandy soil modified with 2.4 % PAM-CS-CaCl₂ aerogel had a water-harvesting capacity of 0.1 g/g (20 °C, 90 % RH) and maintained a water content of 6.74 % under extreme conditions (40 °C, 20 % RH) for 28 days. Under non-irrigated and drought conditions (23-25 °C, 20-30 % RH), sandy soil modified with 0.3-0.6 % PAM-CS-CaCl₂ aerogel extended the survival time of ryegrass from 5 to 12 days. Water harvesting through the use of PAM-CS-CaCl₂ aerogel as a supplement to dry soils may provide a new strategy for water management in arid regions.