Page 142 - AWSAR 2.0

118 || AWSAR Awarded Popular Science Stories - 2019
neoteric term: “What is biochar?”, “How is it obtained?”, “Has it been used earlier?” After an in-depth survey of literature, it became evident that it is not a new concept after all; the technique originated in the Amazon Basin some 2500 years ago. The tribal people would incorporate charcoal up (A: Incorporate in the soil?) to a certain depth and called it ‘terra preta’. Interestingly, these regions have remain fertile till date and are known to support vegetation without any external efforts. Like a ‘phoenix’ rises from its own ashes, the new concept of biochar was born with the ancient idea of ‘terra preta’. A number of studies have been conducted on how various biochar multiplies the crop productivity in agricultural areas and alters the physical, chemical and biological regimes of the soil. However, the application of biochar in an area degraded by a coal mine is still novel and requires the
attention of researches round the globe.
Biochar is a porous, low
density carbon rich material
prepared by the pyrolytic
conversion of organic feedstock
in an oxygen limited or absent
environment, at a temperature
of >250oC for various residence
time. In the course of research,
next question that popped up
was: What kind of biomass could
possibly be used as feedstock
for biochar production? Quintessentially, as the goal
was to use any waste biomass
product, what could be better
than the invasive weeds
growing abundantly in the
mining area. The overburden
material houses these invasive weeds, which can strive in harsh environmental conditions, cause stagnation of succession and act as fuel for the ignition of fire especially in the hot
tropical mining areas in the summer season. They also occupy reclaimed sites, compete for nutrition with afforested plants and cause allelopathy. Lantana camara, Chromolaena odorata (devil weed), Hyptis suaveolens (wild tulsi) and Calotropis procera (milkweed) are few such weeds, which cause nuisance due to their high regenerative capability. Lantana, one of the most notorious weeds, causes problems across the country. These vigorously growing weeds can easily be harvested, converted to biochar and used during reclamation of coal-mine spoil. Thus, the process of biochar production using weeds came into play in an oxygen-limited condition in muffle furnace. After its preparation, it was characterized to study its innate properties so that it could be applied according to the requirement of amendment practice in hand. The
characterization of the biochar showed its highly recalcitrant nature with the potential to fix carbon in the soil for hundreds of years. FTIR depicted the aromatic composition of the biochar samples while the FE- SEM analysis revealed its highly porous surface morphology.
Overburden (OB) material was collected from Tetulmari coal mines, which had adverse physico-chemical and physico- mechanical and biochemical properties for supporting plant growth. These dumps were acidic, stony, highly compact, and lacked moisture, organic matter and soil-forming materials making it unsuitable for supporting vegetation. An
experimental design was setup to study the effect of the weed-derived biochar had on the properties of the OB material. Biochar was applied to the OB material in five treatment
Mine-closure embodies activities such as progressive reclamation and rehabilitation to avert the chances of long- term environmental, socio- economical and physical impacts and development of a landform which can sustain life. This is where the role of eco-restoration lab at the Indian Institute of Technology, Indian School of Mines, Dhanbad, comes into play.