A review on biochar modulated soil condition improvements and nutrient dynamics concerning crop yields: pathways to climate change mitigation and global food security

The beneficial role of biochar on improvement of soil quality, C sequestration, and enhancing crop yield is widely reported. As such we could not find a compiled source of information linking biochar modulated soil condition improvement and soil nutrient availability on crop yields. The present review paper addresses the above issues by compilation of world literatures on biochar and a new dimension is introduced in this review by performing a meta-analysis of published data by using multivariate statistical analysis. Hence this review is a new in its kind and is useful to the broad spectrum of readers. Generally, alkalinity in biochar increases with increase in pyrolysis temperature and majority of the biochar is alkaline in nature except a few which are acidic. The N content in many biochar was reported to be more than 4% as well as less than 0.5%. Poultry litter biochar is a rich in P (3.12%) and K (7.40%), while paper mill sludge biochar is highest in Ca content (31.1%) and swine solids biochar in Zn (49810 mg kg-1), and Fe (74800 mg kg-1) contents. The effect of biochar on enhancing soil pH was highest in Alfisol, Ferrosol and Acrisol. Soil application of biochar could on an average increase (78%), decrease (16%), or show no effect on crop yields under different soil types. Biochar produced at a lower pyrolysis temperature could deliver greater soil nutrient availabilities than that prepared at higher temperature. Principal component analysis (PCA) of available data shows an inverse relationship between pyrolysis temperature and soil pH, and biochar application rate and soil cation exchange capacity.The PCA also suggests that the original soil properties and application rate strongly control crop yield stimulations via biochar amendments. Finally, biochar application shows net soil C gains while also serving for increased plant biomass production that strongly recommends biochar as a useful soil amendment. Therefore, the application of biochar to soils emerges as a ‘win-win strategy’ for sustainable waste management, climate change mitigation and food security

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Soil Science: Fundamentals to Recent Advances (Editors: Amitava Rakshit, S.K Singh, P.C. Abhilash Asim Biswas)Biochar, a pyrolyzed product of biomass, is richer in aromatic carbon (C) and poorer in oxygen which provides structural recalcitrance to it against microbial decomposition in soil. Biochar, being a stable source of C when applied to soil, remains there for longer period of time imparting long-term soil C sequestration. This sequestering effect of biochar has another advantage to mitigate climate change by reducing emission of greenhouse gases (GHGs) from soil. Both the interconnected processes imparted by biochar have its prominent role in climate resilience and environmental sustainability. Researchers around the world have been focusing on this aspect; thus revealing new facts and findings on managing biochar in agriculture. In this chapter, an attempt has been made to describe the biochar-governed mechanisms on emission of GHGs from soil, how the structural and functional properties of biochar regulates that, and the other associated factors like feedstock type and pyrolysis temperature during biochar preparation and soil inherent properties controlling various processes. Similarly, highlights of C sequestration potential of biochar made up of different crop/animal residues and other regulating factors have been described. Increase in pyrolysis temperature and switching over from manure to wood as a feedstock for biochar production increase the stability of biochar and reduce emission of GHGs from soil. The soils low in organic matter trigger C mineralization than that with high organic matter content. Biochar in presence of N fertilizer is reported to enhance CH4 sink/decrease source strength of soil. The strongest effect of biochar on enhancing C sequestration and reducing GHGs emission is evident when it is applied in acid soils than alkaline soils. Both the concurrent processes of C sequestration and GHGs emission bring sanity to soil by physically more stable, enriching soil fertility, biologically more active and resulting to enhanced soil quality and lowering the C-footprint in agroecosystems.Not Availabl

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