Nirmali Bordoloi

Tourism, regardless of its good stimulus, is found to be unhealthy for the environment at times, leaving a significant carbon footprint behind. A study was conducted in the Kodagu district of Karnataka during the months of March and April 2022, identifying carbon footprint as a potent indicator for sustainable tourism to quantify the amount of CO2 emitted by local residents’ energy consumption and tourism-related transport activity. In our study, the electricity consumption has the highest share of carbon footprint, and road transport was found to be responsible for 74% of the total carbon footprint of tourism-related transportation. Although the carbon footprint of local residents of the study area is found to be quite lower than the nation’s per capita carbon footprint, the tourism-related transportation’s carbon footprint is found to be in an alarming situation. Hence, the world must adopt sustainable tourism and regularly monitor whether it is being practised or not to achieve sustainable development by using sustainable indicators to avert any catastrophic situation in future, especially in ecologically sensitive areas like the Western Ghats.

Background: Constant use of chemical fertilizer in agriculture field, degrade overall soil quality and increases the environmental pollution. Integrated nutrient management is an eco-friendly and cost-effective method that involves the combined application of organic amendment and inorganic fertilizer resulting in upgrading soil health, crop productivity, carbon sequestration and mitigating climate change. The current study aimed to examine the combined effects of organic amendment and inorganic fertilizer on soil quality and crop productivity in maize-wheat cropping systems. Methods: A two-year field experiment was conducted in the month of June-October (2021-2022) for maize and Nov-April (2021- 2022 and 2022-2023) for wheat crop. Fertilizer treatments, viz., control (zero fertilizer), NPK (recommended fertilizer), 50% NPK + A. chroococum, 50% NPK + green manure, 50% NPK + karanja cake, 50% NPK + poultry waste, 50% NPK + wheat residue, 50% NPK + maize residue were applied in a randomized block design with four replications. Result: Application of 50% NPK+ poultry waste showed higher soil organic carbon (0.91% and 0.92%) and microbial biomass carbon (353.42 mg kg-1 and 394.35 mg kg-1) followed by 50% NPK+ karanja cake. Application of 50% NPK + poultry waste increased grain yield by 48.5% and 23.25% in maize and wheat respectively over control. Poultry waste, as a replacement for sole NPK, could be a promising strategy for the management of soil health as well as crop productivity.

The burning of agricultural straw is a pressing environmental issue, and identifying effective strategies for the rational utilization of straw resources is decisive for achieving sustainable development. Owing to its high carbon content and exceptional stability, straw biochar produced via pyrolysis has emerged as a key focus in multidisciplinary research. However, the efficacy of biochar in mitigating nitrous oxide (N₂O) emissions from paddy soils is not consistent. A 2-year field experiment was conducted and investigated the impact of biochar derived from two feedstocks (rice straw and wheat straw, pyrolyzed at 450 °C) on N₂O emissions, global warming potential (GWP), greenhouse gas intensity (GHGI), nitrogen use efficiency (NUE), crop yield, and soil quality. The static chamber technique was used for collecting N₂O gas samples, and concentrations were analyzed through gas chromatography methods. The treatment combinations included BR0 (control), BR1 (NPK at the recommended dose, 120:60:40 kg ha⁻¹), BR2 (wheat straw biochar, 5 t ha⁻¹), and BR3 (rice straw biochar, 5 t ha⁻¹). The results exhibited that cumulative N₂O emissions from BR2 and BR3 treatments decreased by 10.55% and 13.75% respectively, compared to BR1. Lower GWP and GHGI were observed under both biochar treatments compared with BR1. The highest rice grain yield (3.48 Mg ha⁻¹) and NUE (76.72%) were recorded from BR3, which also exhibited the lowest yield-scaled N₂O emission. We observed positive correlations between soil nitrate, ammonia and water-filled pore spaces, while NUE showed negative correlations with N₂O emissions. Significant (p < 0.05) improvements in soil quality were also detected in both the biochar treated plots, indicated by increased soil pH, water holding capacity, porosity, and nutrient contents. Overall, the results suggest that applying biochar at a rate of 5 t ha⁻¹ in paddy soil is a viable nutrient management strategy with the potential to reduce reliance on inorganic fertilizers, mitigate N₂O emissions, and contribute to sustainable food production.

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.

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.