Characterization of rice straw from major cultivars for best alternative industrial uses to cutoff the menace of straw burning

Rice straw is a useful bio-resource with worldwide annual production of approximately 731 million tons. However, this valuable biomass is unfortunately burnt on field as waste that causes air pollution, global warming, plant nutrient losses and environment menace. About 60% of rice straw produced in Asia in general and India in particular is burnt in field. As for the basic requirement to predict their suitability for best alternative industrial uses biochemical, morphological and chemical (functional group) characterization of straws of 18 most widely grown rice cultivars from eastern region of India was carried out. Biochemical characterization was done on the basis of cellulose, hemicellulose, lignin and silica content. The surface morphology of straws was observed through Scanning Electron Microscopy (SEM), while, presence of functional groups were analyzed through Fourier Transform Infrared (MR) spectroscopy. Primarily, quantified biochemical profiles were used to group cultivars for best alternate uses of straw like bio-ethanol, biochar, compost and mushroom production. Morphological feature (from SEM) of straw and functional group (through FUR) were used to support the grouping. Cultivars with higher hemicelluloses and cellulose with low to medium lignin and Si were better suited for bio-ethanol production while, straw having higher lignin and low to medium cellulose and hemicellulose were selected for biochar. Therefore, considering all the three characterization methods (chemical composition, morphological features, presence or absence of functional groups), we found straws of rice cultivars, Tapaswini and IR 64 were best suited for bio-ethanol and biochar production, respectively. There are overlapping as well as contradictory observations found during grouping, when the three approaches were followed together. This indicate that the grouping of straw for better alternative uses could be done by biochemical and morphological characterization but this should be validated in small scale at farm or factory level for final recommendation.