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Nitrous oxide (N2O) is an important long-lived greenhouse gas and is a dominant contributor to stratospheric ozone depletion. Mitigating N2O emission from the rice paddies is one of the important challenges to global food security and climate change research while sustaining optimum productivity. We conducted a 2-year experiment to investigate the effect of different plant growth regulators (PGRs) on N2O emission to the atmosphere. The PGRs namely abscisic acid and cytozyme (20 mg L−1), kinetin (10 and 20 mg L−1) and tea extract (1:20 w/w) along with distilled water as control were sprayed at the tillering and panicle initiation stages of rice crop. Abscisic acid and kinetin (10 and 20 mg L−1) were found to bring about a significant (p

Agricultural soils are an important source of greenhouse gas nitrous oxide (N2O) emission. The comprehensive effects of nitrogen fertilizer management on N2O emission from paddy fields of India have not been evaluated under field conditions. A 2-year field study was conducted to evaluate the effect of different nitrogen fertilizers, namely, conventional fertilizer (NPK), starch-coated urea (SCU), neem-coated urea (NCU), and normal urea alone (NUA) on soil quality, grain yield, and N2O emission from rice field. Gas samples were collected from the field at weekly intervals by static chamber technique and analyzed in a gas chromatograph. During the crop-growing season, the application of NPK resulted in the highest cumulative N2O emission (2.49 kg N2O–N ha−1) followed by NUA (2.34 kg N2O–N ha−1), NCU (2.20 kg N2O–N ha−1), and SCU (1.97 kg N2O–N ha−1). As against the application of conventional fertilizer (NPK), the application of SCU and NCU reduced the total N2O emission by 21% and 12%, respectively (p

Identification of the combination of tillage and N fertilization practices that reduce agricultural Nitrous oxide (N2O) emissions while maintaining productivity is strongly required in the Indian s...

Agricultural soil acts as a source and sink of important greenhouse gases (GHGs) like methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2). Rice paddies have been a major concern to scientific community, because they produce the threatening and long-lasting GHGs mainly CH4 and N2O. Around 30% and 11% of global agricultural CH4 and N2O, respectively, emitted from rice fields. Thus, it is urgent to concurrently quantify the fluxes of CH4 and N2O to improve understanding of both the gases from rice fields and to develop mitigation strategies for upcoming climate change reduction. An effort is being made in this review to discuss exclusively the emission of CH4 and N2O under normal and controlled conditions in different locations of India and also addresses the current synthesis of available data on how field and crop management activities influence CH4 and N2O emissions in rice fields. Making changes to conventional crop management regimes could have a significant impact on reducing GHG emissions from rice field. Environmental and agricultural factors related to soil could be easily altered by management practices. So, knowing the mechanism of CH4 and N2O production and release in the rice field and factors controlling the emissions is fundamental to develop well-organized strategies to reduce emissions from rice cultivated soil. This will help the regulatory bodies or policy makers to formulate adequate policies for agricultural farmers to refine the GHG emissions as well as minimize the global climate change.

Environmental contamination is one of the paramount concerns engulfing the entire world. Being nondegradable in nature, heavy metals (e.g., Ni, Cd, Cu, As, Hg, and Pb) are significant pollutants of soil and aquatic ecosystems. Although numerous technologies have been employed to remove toxic metals from contaminated sites, there is still need for more efficient and ecologically sound methods. The use of algal species for the removal of heavy metals as well as other contaminants like dyes, nutrients, ions etc. from water and wastewater, which is popularly known as phycoremediation, has been found to be eco-friendly, ecologically sound, and a value-added tool. The common algal species which are being used for phycoremediation are Chlorella, Scenedesmus, Oscillatoria, Lyngbya, Gloeocapsa, Spirulina, Chroococcus, Synechocystis, and Anabaena. The use of algae for the removal of pollutants also helps in carbon sequestration and biofuel production. This chapter discusses the removal of toxic metals from contaminated aquatic ecosystems using various species of micro- and macroalgae along with factors that influence the process of phycoremediation and the role of algae in biofuel production and carbon sequestration.

The excessive use of synthetic nitrogen fertilizer in agriculture interferes in natural ecosystem functioning and pollutes the environment through nitrogen leaching, volatilization, nitrification, and denitrification. The consumption of conventional fertilizer in the agricultural field has increased nitrous oxide (N2O) emission, an important trace gas, which is responsible for stratospheric ozone layer depletion and global warming. Alternatively, the use of slow-release fertilizer (SRF) is considered to ameliorate crop nitrogen use efficiency (NUE) and yields while minimizing problems related to environment caused by inorganic N-fertilizer. For SRF, the coating of urea particles can be done with various coating materials; thus, nutrients release slowly from coated fertilizer and plant can efficiently use it. The degree of N release to soil depends on the coating material being used. Starch is one type of encapsulating polymer which can be used to coat or encapsulate the urea granules to slow the rate of fertilizer release. Although starch is mineralizable, the addition of different cross-linking agents reduces the release rate of entrapped urea from their cross-linking structure. The presence of coating directly retards the ammonium (NH4+) oxidation by reducing the activity of nitrifying bacteria and indirectly reduces the substrate availability for denitrification in soil. In this chapter, we have briefly reviewed about the different types of SRF and its use in the different agroecosystems. The efficiency of SRF for the reduction of greenhouse gas from rice and wheat ecosystems, mainly N2O emission by affecting nitrification and denitrification process in soil, has also been discussed.

The burgeoning population and continuous increase in developmental activities are the major cause of rampant release of numerous environmental contaminants. These contaminants pollute the soil, air and water and ultimately enter the food chain. Several physical, chemical and biological techniques have been developed to remove these contaminants; however, these methods are quite costly and not environmentally sound. Specifically, organic contaminants like pesticides, phenols, oils, pharmaceuticals and dyes are entering aquatic habitats and damaging these ecosystems. Application of aquatic macrophytes for the removal of organic contaminants has proved to be an eco-friendly and efficient tool to remediate aquatic ecosystems. Aquatic macrophytes such as Eichhorn crassipes, Elodea canadensis, Lemna minor, Pistia stratiotes, and Trapa natans can be used for reclamation of contaminated waste and wastewater systems. In addition, these plants help in carbon sequestration, and the biomass of these plants may be used to produce bioenergy (biofuel) at the same time. In this chapter, the potential of aquatic macrophytes for phytoremediation and bioenergy production along with carbon sequestration have been thoroughly discussed.

Global climate change is one of the most prominent and complex environmental problems caused by increasing concentrations of atmospheric greenhouse gases. Rice paddies are an important anthropogenic source of nitrous oxide (N2O), a greenhouse gas approximately 298 times stronger than carbon dioxide. Identifying a suitable mitigation method for N2O emissions from rice agriculture, while maintaining optimum crop productivity is strongly needed. A 2-year field study was conducted on rice to assess N2O emissions in response to the application of different plant growth regulators (PGRs). The PGRs abscisic acid (ABA) and cytozyme (20 mg L−1), kinetin (10 and 20 mg L−1) and wet tea extract (1:20 w/w) along with distilled water as control were sprayed at the tillering and panicle initiation stages of rice. Compared with control treatment, exogenously applied ABA and kinetin (10 and 20 mg L−1) significantly (p

Agricultural soils are the major source of global nitrous oxide (N2O) emission, and more than two thirds of N2O emission originate from soil. Recent studies have identified that green plants contribute to transport of N2O to the atmosphere. We investigated the effects of foliar application of plant growth regulators (PGRs) and growth stimulating chemicals on N2O emission and wheat grain yield for 2 years. The PGRs’ abscisic acid (ABA) and cytozyme (20 mg L−1), kinetin (10 and 20 mg L−1) and wet tea extract (1:20 w/w) along with distilled water as control were sprayed on wheat canopy at the tillering and panicle initiation stages. Our results showed that cytozyme and tea extract enhanced the plant dry biomass over control. Kinetin (10 and 20 mg L−1) and cytozyme increased the plant photosynthetic rate and photosynthate partitioning towards the developing grain. ABA (20 mg L−1) and kinetin (10 and 20 mg L−1) reduced the N2O emission over control primarily through regulation of leaf growth, stomatal density and xylem vessel size. Leaf area, stomatal density and xylem vessel size were found to be associated with N2O transport and emission. We concluded that use of ABA and kinetin can reduce N2O emissions without any impact on wheat grain yield.

Wetlands are one of the most productive ecosystems that support diverse habitats and biodiversity and are known for its various ecosystem goods and services. About half of global wetlands have found to be lost, and the conditions of remaining wetlands are deteriorating due to natural as well as anthropogenic cause. The negative economic, social, and environmental significances of diminishing water quality in wetlands are one of the major issues of concern for degraded wetlands in India. Thus, it is imperative to emphasize on the restoration of the degraded wetlands along with the conservation and management of the existing wetlands since they are one of the most valuable and fragile components of the watershed. The present research strongly suggests the management practices for wetland conservation should be based on the traditional knowledge and resource uses that will eventually aid in fostering biodiversity and preserving key ecosystem services in cost-effective and sustainable way.

Agricultural soils are an important source of greenhouse gas nitrous oxide (N

We investigated nitrous oxide (N2O) emission from an irrigated rice field over two years to evaluate the management of nitrogenous fertiliser and its effect on reducing emissions. Four forms of nitrogenous fertilisers: NPK at the recommended application rate, starch–urea matrix (SUM) + PK, neem-coated urea + PK and urea alone (urea without coating) were used. Gas samples were collected from the field at weekly intervals with the static chamber technique. N2O emissions from different treatments ranged from 11.58 to 215.81 N2O-N μg/m2/h, and seasonal N2O emissions from 2.83 to 3.89 kg N2O-N/ha. Compared with other fertilisers, N2O emissions were greatest after the application of the conventional NPK fertiliser. Moreover, SUM + PK reduced total N2O emissions by 22.33% (P

This work dealt with the determination of the suitability of sorption of Volatile Organic Compounds (VOCs) on biochars prepared from neem, sugarcane and bamboo feedstocks. Six different VOCs namely benzene, toluene, methyl chloride, xylene, chloroform and carbon tetrachloride were used in a laboratory-scale set-up on non-activated biochars prepared via slow pyrolysis (350–550 °C). Although all the chars showed considerable sorption but amongst them N3 (neem-based biochar) showed the maximum removal efficiency (65.5 mg g−1 for toluene). Variation in pyrolysis temperature and feedstock type showed significant change in the porosity and specific surface area of the biochar, which is favorable for VOC sorption efficiency. With higher surface area and contact time, the sorption capacity of char enhanced. However, the extent of sorption capacity of biochars differed with changing VOC type. Pseudo-Second-Order model fitted well with the results obtained from VOC sorption kinetics.

Agricultural soils are the major source of global nitrous oxide (N

Nitrous oxide (N2O) is considered a major contributor to global climate change in addition to carbon dioxide and methane. A significant quantity of N2O emission originates from agriculture, largely from high rates of fertiliser application. We studied N2O emissions from wheat field to evaluate the effect of different forms of fertilisers and the potential for emission reduction. Field experiments were conducted for two consecutive seasons with four fertilisers, namely inorganic fertiliser (NPK), starch-coated urea (SCU), neem-coated urea (NCU), and urea alone (UA) in a tropical wheat ecosystem. Gas samples were collected from the field at weekly intervals using the static chamber technique and analysed with a gas chromatograph. The cumulative N2O emissions were higher from the NPK amended field (3.19kgN2O-Nha–1) followed by UA (3.05kg N2O-N ha–1). The SCU, NCU, and UA amendments decreased the total N2O emissions by 23%, 12%, and 4%, respectively (P

Nitrous oxide is a greenhouse gas with high global warming potential emitted from agricultural sources. The effects of tillage practices and different levels of N fertiliser on seasonal fluxes of N2O were investigated in a field planted with the wheat variety Sonalika. The experiment was conducted during 2012–13 and 2013–14 under conventional tillage (CT) and reduced tillage (RT) farming systems in combination with four different levels of nitrogen fertiliser (i.e. zero nitrogen (F1), 60kgNha–1 (F2), 80kgNha–1 (F3) and 100kgNha–1 (F4)). Both tillage practices and fertiliser significantly (P