Considerable interest is being shown in using biochar production from waste biomass with a variety of disciplines to address the most pressing environmental challenges. Biochar produced by the thermal decomposition of biomass under oxygen-limited conditions is gaining popularity as a low-cost amendment for agro-ecosystems. The efficiency of biochar formation is affected by temperature, heating rate, feedstock type, particle size and reactor conditions. Properties such as pH, surface area and ash content of produced biochar increases with increasing temperatures. Biochar produced at lower heating rates may have high porosity and be beneficial for morphological changes in the soil. Biochar can help to enhance soil health and fertility as well as improve agricultural yield. As a result, biochar can assist in increasing food security by promoting sustainable agricultural systems and preserving an eco-friendly environment. Biochar is also widely being used as a sorbent for organic and inorganic pollutants, owing to its large surface area, allowing it to be immobilized from soil with ease. The functional groups and charges present on the surface of biochar play an important role in pollutants removal. This review focuses on the mechanisms of biochar production using different waste materials as a feed stock, factors that influence biochar quality as well as application of biochar in agricultural soil and their reclamation as well. This article also discusses knowledge gaps and future perspectives in the field of biochar-based toxic-pollution remediation.

In the modern era, due to urbanization, industrialization, and anthropogenic activities in the catchment, greenhouse gas (GHG; CO₂, CH₄, and N₂O) emissions from freshwater ecosystems received scientific attention because of global warming and future climate impacts. A developing country such as India contributes a huge share (4% of global) of GHGs from its freshwater ecosystems (e.g., rivers, lakes, reservoirs) to the atmosphere. This is the first comprehensive review dealing with the GHG emissions from Indian freshwater bodies. Literature reveals that the majority of GHG from India is emitted from its inland water, with 19% of CH₄ flux and 56% of CO₂ flux. A large part of India’s gross domestic product (GDP) is manipulated by its rivers. As a matter of fact, 117.8 Tg CO₂ year⁻¹ of CO₂ is released from its major riverine waters. The potential of GHG emissions from hydropower reservoirs varies between 11–52.9% (mainly CH₄ and CO₂) because of spatio-temporal variability in the GHG emissions. A significant contribution was also reported from urban lakes, wetlands, and other inland waters. Being a subtropical country, India is one of the global GHG hotspots, having the highest ratio (GHG: GDP) of 1301.79. However, a large portion of India’s freshwater has not been considered yet, and there is a need to account for precise regional carbon budgets. Therefore, in this review, GHG emissions from India’s freshwater bodies, drivers behind GHG emissions (e.g., pH, mean depth, dissolved oxygen, and nutrients), and long-term climatic risks are thoroughly reviewed. Besides research gaps, future directions and mitigation measures are being suggested to provide useful insight into the carbon dynamics (sink/source) and control of GHG emissions.

Climate change and agriculture have a dual mode of relationship. Agriculture is an important sector of the country’s economy and it significantly contributes to climate change by releasing greenhouse gases (GHGs) to the atmosphere. On the other hand, climate change is a global threat to food security and it can affect agriculture through variation of weather parameters. Reducing GHGs emission mainly methane (CH4) and nitrous oxide (N2O) from the agriculture could play a significant role in climate change mitigation. N2O is a potent greenhouse gas mainly emitted from rice-wheat cropping system. Agricultural lands are considered as one of the important anthropogenic sources of N2O emissions and it account almost 69% of the annual atmospheric N2O emission and application of commercial fertilizers is considered as a major contributor to the N2O emission. This book chapter focuses on the feasible soil and crop management practices to reduce the N2O emission from agriculture without compromising the productivity. Different environmental factors that have a major impact on N2O production are also discussed in this chapter. On urgent basis, the world needs to reduce the anthropogenic N2O emissions from agriculture and adapt its sustainable cropping system and food-production system to survive with climate change.