**1. Introduction**

In this 21st century, feeding the teeming millions is the greatest challenge before us. The green revolution of 1960s although could alleviate the growing demands for food to a great extent but at the cost of food quality and environmental health. Long term applications of chemical fertilizers in crop production systems have been resulting in unpredictable reduction in yields and increase in the cost of cultivation. However, with the shrinking land, the burgeoning competition for water, land and other resources from non-agriculture sector might aggravate agricultural production in the near future. Hence, intensive farming through enhanced cropping intensity has been the way out for mitigating the population driven demands for food, feed, fodder and fibre without much scope for recycling of the agricultural wastes in majority of cases. For raising of multiple crops in a year the farmers burn farm residues *in-situ* in absence of appropriate sustainable recycling technologies that ultimately pollute the environment and increase carbon foot print. Globally, annual plant waste production is estimated at around 5.5 billion tons in 2013 that accounts for 13 per cent of the greenhouse gas emission from agriculture sector [1]. Some of these wastes are although used as cattle feed and organic manure but a plenty are still available for alternative uses. Hence, it is high time to adopt the best possible technologies for recycling of bio-wastes from crop fields for harnessing the nutrients and green energy as well.

Near about half of the habitable land on this planet is under agriculture [2]. Of the 1,600 million hectares of cultivated land [3], 50.8 per cent is occupied by cereals [4]. About 52.5 per cent calories for humans are available from cereals at global scale [4] with major contributions from corn (1,116.34 million tons), wheat (764.49 Mt), rice (495.78 Mt), barley (156.41 Mt), sorghum (57.97 Mt), oat (22.83 Mt) and rye (12.17 Mt) [5]. Cereals are special not because of their uses as staple food but due to production of ethanol and cattle feed in many advanced nations. However, in many underdeveloped and developing countries this precious wealth has not yet been fully utilized [6]. It is high time to use this precious waste from crop field in judicious manner not only to recycle the carbon and sequester it back into the soil but also to harness clean and green energy out of it through appropriate measures.
