Remediation of degraded soils with hydrogels from domestic animal wastes

Authors

1 Kenyatta University

2 University of Johannesburg

Abstract

Introduction This study reports on water management in the felds found in arid areas by the improvement of the soil’s water retention capacity. This was done using hydrogels from animal wastes to mitigate the efects of climate change that lead to rapid evaporation of water hence increased desertifcation rates. Method The modifcation of the cow dung to hydrogels involves the oxidation of urea or uric acid from chicken dung to form compounds that can undergo a condensation reaction with cellulose in the cow dung. This formed a product with high water retention capacity. Results The materials were characterized using Fourier transform infra-red spectroscopy and thermo-gravimetric analysis which confrmed the derivatization of some functional groups. The thermo-stability was improved, as the degradation temperatures for urea, glycerol, and chicken dung derivatives were 245, 220, and 228 °C, respectively, while the unmodifed form was 198 °C. The UV–Vis analysis showed no evidence of starch in the modifed material which was also confrmed by Lugol’s test. It was found out that modifcation had infuence on the swelling ability giving it superabsorbent properties with swelling capacities (300 g g−1) within 5 min of moisture exposure plus a high water retention capacity of 90%. Conclusions The application of the modifed materials in the growing of some selected plants showed that the moisture content could be sustained for a period of 6 weeks before the plants wilted. This confrms that the modifed form of manure has potential application for hydration of plants in arid areas.

Keywords