Soil Quality" is the capacity of a specific kind of soil to function within natural or managed ecosystem boundaries to sustain plant and animal productivity, maintain or enhance water and air quality and support human health and habitation. One of the major threats for soil quality is the intensive use of agrochemicals coupled with soil degradation processes. Vermicomposting has emerged as a promising eco-friendly approach for recovering degraded soils and equally good is the application of biochar, a carbonaceous material produced from pyrolysing biomass for both remediation and for soil carbon storage potentials. The vermicompost and biochar mentioned in the present study are rice straw based products. The lower bulk density of straw and its products compared to soil shows its promising role in reducing the soil bulk density and increasing the porosity besides its capability to hold more water when applied to soil. The process of vermicomposting helped to increase the nutrients viz., N, P, K, Ca, Mg, S, and silicon and decrease that of carbon, cellulose and lignin thereby narrowing down the C: N ratio. Conversion of residues into biochar helped to increase content of most of the nutrients in the final product, while nitrogen, cellulose and lignin content were found to decrease after pyrolysis. Pyrolysis process imparted more recalcitrant character by increasing aromatic compounds as evidenced from FT-IR analysis, thus ensuring its suitability for carbon sequestration.

Production of biochar and composting of the residue are the effective and proven residue management strategies that have high potential to improve soil properties and crop productivity. The milling of paddy yields large amount of husk. As a part of the present investigation, both biochar as well as vermicompost were prepared from the rice husk. Surface morphology and structural characteristics of rice husk, biochar and vermicompost were examined using Scanning Electron Microscope (SEM) and Fourier Transform Infra-Red (FTIR) spectrometer equipped with Attenuated Total Reflectance. SEM image of rice husk exhibited well-arranged micro-bumps on the surface. Whereas, the SEM image of biochar was porous, fragmented and heterogeneous. In the micrograph of vermicompost, undecomposed rice husk structure was visible. It indicated that technology of composting rice husk using earthworms was not much suitable. Each peak in FTIR was assigned with corresponding functional groups and it clearly explained the presence of C, H, O, N and Si in the rice husk and products. The FTIR spectra of rice husk and vermicompost were almost similar whereas characteristic differences were noted in biochar spectrum. FTIR spectra of rice husk biochar revealed its aromatic and recalcitrant nature. Pyrolysis process created more recalcitrant character by increasing aromatic compounds, and thus could help in sequestering carbon in soil.