Biochar Production and its Use in Rainfed Agriculture: Experiences from CRIDA

Abstract

Maintaining soil organic matter is a prerequisite to ensure soil health and crop productivity in rainfed farming. India ranks first among the countries that practice rainfed agriculture. Out of the estimated 141 Mha net cultivated land in India, about 75 Mha is rainfed, spread over 177 districts of the country and produces about 40% of the total food grain in India. Efficient use of crop residue based amendment in soil is an important strategy to improve the soil fertility and productivity in rainfed areas. Annually 500 Mt crop residues are generated in India, out of which 141 Mt is surplus. Among different crops, oilseeds (29 Mt), pulses (13 Mt) and cotton (53 Mt) generate maximum residues in India, which are advertently niche crops for rainfed areas. The surplus crop residues of castor, cotton and pigeonpea stalk are estimated to be 18.0, 11.8 and 9.0 Mt, respectively. These residues are either partially utilized or un-utilized due to various constraints. Surplus and unused crop residues when left unattended, often disrupt land preparation, crop establishment and early crop growth, and therefore are typically burnt on farm which causes environmental problems and substantial nutrient losses. For more effective management and disposal of the crop residues, their conversion into biochar through thermo-chemical process (slow pyrolysis) is gaining importance as a novel and economically alternative way of managing unusable and excess crop residues. Much of the stimulus for this interest has come from research on the soils of the Amazon basin, known as Terra Preta de Indio, that contain variable quantities of organic black carbon considered to be of anthrogenic origin. Conversion of crop and on-site agroforestry residues to biochar and its soil application as an amendment can turn the hitherto excess residues available in India into a useful materiel for enhancing soil health and crop productivity. Biochar production and application to soil has potential advantages as soil amendment covering benefits beyond carbon sequestration. This includes improvement of soil physical properties that benefit crops, improved retention and availability of soil nutrients, improved biological activity and consequently higher crop yields and societal advantages through mitigation of global warming through carbon sequestration. These benefits provide the basis for up scaling of biochar use in rainfed agriculture. Globally, few studies have focused on the use of biochar in rainfed areas. This research bulletin documents the research outcomes from ICAR-CRIDA on biochar kiln development, kiln operational procedures and standardization of biochar production protocols from different residues and biochar characterization methods and its properties, its use in rainfed Alfisols and response of pigeonpea and maize to different biochar types, rates of application and schedules. We hope that this publication would be very useful to researchers, academicians, policy makers and students on biochar production and its use in rainfed agriculture.