Reclamation of industrial waste dump using grass-legume mixture: An experimental approach to combat land degradation

Abstract

The amount of solid waste generated by the industrial processes increased tremendously due to rapid industrialization. This waste contains hazardous material and unscientific disposal leads to land degradation and environmental pollution. Therefore, it must be managed carefully to reduce adverse environmental effect and restore ecosystem function. The study aims to evaluate the potential of grass (Pennisetum pedicellatum) and legume (Stylosanthes hamata) revegetation to restore the soil fertility of a steel and iron ore solid waste dump in central India. A field experiment was carried out at the reclaimed site without seeding (control), 1-year and 5-year after direct seeding of grass-legume mixture to assess the changes in soil fertility and biomass production. Soil samples (0–10 cm and 10–20 cm) were collected by laying random quadrats and analyzed for physicochemical and biological properties. Plant biomass and nitrogen (N) mineralization potential of accumulated mulch were measured along the age chronosequence. Soil fertility in terms of organic matter (SOM; 1.61%), organic carbon (SOC; 1.03%), Av. N (132.1 mg kg−1), and enzyme activity (dehydrogenase; 5.32 μg TPF g−1 h−1 and urease; 7.11 μg NH4+ g−1 h−1) at the 5-year-old revegetated site was significantly greater than that of the control site. Plant biomass (32.5–45.8 Mg ha−1) and mulch density (11.4–28.0 Mg ha−1) increased after 1- to 5-year of revegetation. Biomass C:N ratio was higher in grass while cumulative N-mineralization by legume was three times higher than in the grass. Soil moisture, SOM, microbial biomass carbon (MBC) and nitrogen (MBN), and mineralizable N increased with the mulch thickness (3–12 cm). The study concludes that direct seeding of grass-legume mixture potentially recuperates the soil fertility and increase biomass production that help ecosystem restoration. Direct seeding of the grass-legume mixture can be a promising ecological restoration tool to combat land degradation and to achieve UN sustainable development goals.