BIOCHAR-BASED SOIL MANAGEMENT FOR ENHANCING BARNYARD MILLET (ECHINOCHLOA FRUMENTACEA (ROXB.) LINK) PRODUCTION UNDER RAINFED CONDITIONS: A REVIEW

Abstract

Barnyard millet (Echinochloa frumentacea (Roxb.) Link) is a short-duration cereal that fits well into low-input and rain dependent production systems. Its adaptability makes it valuable where rainfall is uncertain, yet yields in such environments are often restricted by depleted organic matter, weak nutrient supply and limited soil-water storage. Biochar, produced by heating biomass under oxygen-limited conditions, has attracted attention as a durable soil amendment capable of modifying several soil properties at the same time. Published evidence indicates that biochar can decrease soil bulk density, improve aggregation and pore characteristics, increase water retention, and contribute to nutrient retention. Nevertheless, the magnitude and direction of these effects are strongly influenced by feedstock, pyrolysis conditions, soil texture, soil reaction, application rate and crop management. Meta-analyses have reported an overall positive effect of biochar on crop productivity, but responses vary considerably among environments. Combining biochar with compost, farmyard manure, biofertilizers or recommended mineral fertilization may be more effective than using biochar as a stand alone input. Direct evidence for barnyard millet is still limited, and consequently biochar rates or combinations should not be presented as universal recommendations. This review examines the scientific basis for using biochar in rainfed barnyard millet, with emphasis on soil physical and chemical improvement, nutrient-use efficiency, water-stress mitigation, carbon management, locally available feedstocks, limitations and future research requirements.