In the context of increasing water scarcity and environmental pollution, this study investigates the synthesis and application of p(AA-Oco-AAm)-g-Citrus Sinensis Peel hydrogel (CSP hydrogel) to enhance soil water retention and remove organic dyes from wastewater. Hydrogels were prepared using a combination of acrylamide and acrylic acid, with the incorporation of citrus peel as a natural resource. The water absorption capacity of the hydrogels was evaluated, achieving a maximum retention rate of 477 g/g, significantly improving the water-holding ability of various soil types. Additionally, the hydrogels demonstrated a strong affinity for methylene blue, with an equilibrium adsorption capacity reaching 2299.45 mg/g, indicating their effectiveness in wastewater treatment. Kinetic and isothermal adsorption models were applied to analyze the adsorption dynamics, revealing a superior fit to the Langmuir model. The hydrogels maintained structural integrity and reusability over multiple cycles, underscoring their potential for sustainable agricultural practices and environmental remediation. This research highlights the dual benefits of utilizing agricultural waste for the development of eco-friendly materials while addressing critical challenges in water management and pollution control.

The Qinghai–Tibet Plateau’s alpine grasslands are ecologically vulnerable. Plateau zokors build mounds that modify soil and vegetation, influencing soil biota. This study examined how different vegetation on zokor mounds affects soil nematodes and ecosystem function. We compared undisturbed grassland (CK), Potentilla anserina (PM) and Leontopodium (LM) mounds, and new bare mounds (NM). Soil nematode communities were analyzed to assess functional indices and metabolic footprints. Compared with CK, PM increased total nematode abundance by 37.74%, r-strategists by 36.54%, and K-strategists by 39.37%. NM increased dominance (λ) by 22.20%, channel ratio (NCR) by 8.89%, and the Wasilewska index (WI) by 1.24 times, but reduced Shannon diversity by 8.49%, trophic diversity (TD) by 22.84%, and species richness (SR) by 29.40%. LM decreased the maturity index (MI) of free-living nematodes by 7.19% and increased the plant parasite index (PPI) by 10.01%. PM exhibited the highest metabolic footprints for bacterivores, fungivores, omnivores/predators, and total nematodes. Soil carbon (EF-C), nitrogen (EF-N), phosphorus (EF-P) cycling functions, and overall ecosystem multifunctionality (EMF) were highest in CK and lowest in LM. Soil moisture had positive effects on EF-N, EF-P, and EMF, whereas pH had a negative effect on EF-C. These findings demonstrate that vegetation-covered zokor mounds influence nutrient cycling and ecosystem multifunctionality through changes in nematode community characteristics, providing new insights into soil biodiversity–function relationships and informing grassland restoration strategies in high-altitude ecosystems.