Water retention and sustained release of magnesium-based biochar modified hydrogel composite materials

In recent years, the low utilization efficiency of fertilizers and the scarcity of freshwater resources caused by globalization have received widespread attention. To address these issues, this study used an in-situ polymerization method to prepare a magnesium-based biochar modified hydrogel slow-release fertilizer (Mg-NBC/PAA) by combining magnesium-based biochar slow-release fertilizer (Mg-NBC) with polyacrylic acid hydrogel. The composition and properties of the material were characterized using various techniques, including FT-IR, SEM, XPS, and CA. The results show that the Mg-NBC successfully entered the network structure of the hydrogel material, and the hydrogel with added biochar exhibited higher water absorption performance than the pure hydrogel, with an improvement of 47.12%. Under the optimal synthesis conditions, the maximum water absorption capacity of the material was 1395.12 ± 35.45 g/g, which can increase soil water retention and holding capacity after being added to the soil. Moreover, the material also significantly promoted the growth of maize seedlings. Therefore, Mg-NBC/PAA has the potential to be widely used in sustainable agriculture, especially in dry and semi-arid areas, due to its ability to maintain soil moisture, reduce irrigation water use, and improve nutrient utilization efficiency.