Kinetics and Mechanism of the Oxidation of Aliphatic Aldehydes by Benzimidazolium Dichromate

Kinetic and mechanistic studies of the oxidation of aliphatic aldehydes, (in organic non-aqueous solvents), were discussed with an emphasis of correlation of structure and reactivity. The reactions were of first order with respect to BIDC and hydrogen-ion. However, Michaelis-Menten type kinetics were observed with respect to aldehyde. The deuterium isotope effect for the oxidation of acetaldehyde (kH/kD = 6.36 at 298 K) indicated an α-C–H bond cleavage in the rate-determining step. Based on kinetic data, analyses of the solvent effect and results of structure-reactivity correlation along with some nonkinetic parameters suggested a mechanism involving rate-determining oxidative decomposition of a aldehyde- BIDC complex via a cyclic transition state to give a carbocationic species through hydride-ion transfer from the aldehyde to the oxidant. (doi: 10.5562/cca1694

Flue Gas Desulfurization Gypsum as Soil Amendment

Flue gas desulfurization (FGD) gypsum is one of the by-products of a coal-fired power generation plant. Coal is the world’s most abundant and widely distributed fossil fuel. After natural gas, coal is the second primary source of energy to generate electricity globally (more than 25%) and remains a key component of the fuel mix for power generation to meet electricity demand in most of the developing countries. The U.S., China and India are the top coal producers and consumers (for production of electricity from coal sources) in the world (OECD/IEA, 2014; IEA, 2016). However, in the U.S., its contribution to power generation is declining in favor of natural gas and other energy sources due to low natural gas prices, renewable energy standards and environmental activism and regulations. Coal combustion in power plants generates about 120 million metric tons of coal combustion residues (CCR) annually. These by-products include fly ash, bottom ash, flue gas desulfurization (FGD) material and flue bed combustion ash. According to the American Coal Ash Association (ACAA, 2015), only 61.1 million metric tons of CCR were beneficially used. The 1990 U.S. Clean Air Act Amendments restrict sulfur dioxide (SO2) emissions into the atmosphere from coal-fired facilities, if the coal contains considerable amounts of sulfur (S). To meet the SO2 emission reduction requirements, most of the U.S. coal power plants use the FGD process, and in this process, the gypsum is produced which is known as FGD gypsum. FGD gypsum is created by forced oxidation scrubbers in coal-fired power plants which remove SO2 emission from the flue gas stream. There are three different scrubbing processes: wet, semi-dry and dry. However, SO2 removal efficiencies are significantly higher in wet scrubbing process (90 to 98%) than semi-dry (80 to 90%) and dry (50 to 60%) processes for calcium-based sorbents (Schnelle and Brown, 2002). In general, a wet scrubbing process first exposes the flue gases to a slurry of hydrated lime, where it reacts with S in the gas to form calcium sulfite (CaSO3). Forcing additional air into the system oxidizes the CaSO3 and converts it into gypsum. The FGD gypsum is also known as recaptured gypsum, byproduct gypsum and synthetic gypsum. The chemical formula for mined gypsum or FDG gypsum is the same, which is calcium sulfate dihydrate (CaSO4•2H2O). By weight, it is 79% calcium sulfate and 21% water. It contains 23% calcium (Ca) and 18% sulfur (S). However, the amount and types of trace materials and unreacted sorbents found in the gypsum can vary among power plants and among mines. FGD gypsum contains 90 to 99% of purity concentration compared to 66 to 98% concentration in mined gypsum. Production of FDG gypsum has gradually increased in the past several years. According to the ACAA, approximately 33 million metric tons of FDG gypsum was produced in 2015 in the U.S., of which 53% (17.5 million metric tons) was used in building industry and road construction. Less than 2% of the total FGD gypsum production was used in agriculture

Assessment of Soil Fertility under Different Land-Use Systems in Dhading District of Nepal

Unscientific land use and cropping techniques have led high soil erosion and degradation of soil quality in the mid-hills of Nepal. To understand the effects of land use systems for selected soil chemical properties in mid-hills, composite soil samples at 0 cm to 20 cm depth were collected from five different land-use systems: Grassland, forest land, upland, lowland, and vegetable farms from Dhading district of Nepal in 2017. Soil samples were analyzed for soil fertility parameters: Soil pH, organic matter (OM), total nitrogen (N), available phosphorus (P), available potassium (K) and its effect due to different land use systems were compared. Results showed that soil pH was neutral in vegetable farms (6.61), whereas the rest of the land-use systems had acidic soils. Soil OM (3.55%) and N (0.18%) content was significantly higher in forest, but the lowest soil OM (1.26%) and N (0.06%) contents were recorded from upland and lowland farms, respectively. Available P was the highest in the vegetable farm (41.07 mg kg–1) and was the lowest in grazing land (2.89 mg kg–1). The upland farm had significantly higher P levels (39.89 mg kg–1) than the lowland farm (9.02 mg kg–1). Available K was the highest in the vegetable farm (130.2 mg kg–1) and lowest in grazing land (36.8 mg kg–1). These results indicated that the land under traditional mixed cereal-based farming had poor soil health compared with adjacent vegetable, grazing, and forest lands among the study area. The variations in soil fertility parameters suggest the immediate need for improvement in soil health of traditional farmlands

Spatial variability of soil properties under different land use in the Dang district of Nepal

Increased nutrient mining, soil erosion, and limited nutrient management has led to declines in soil quality and reduced productivity in many parts of Nepal. A study was conducted in the eastern part of the Dang district of Nepal in 2015 to assess the variability of selected soil properties of three different land use types (agricultural, agroforestry, and grassland) and to map their spatial distribution. A total of 120 soil samples were collected from 0–15 cm depth and analyzed for soil fertility parameters: pH, organic matter (OM), nitrogen (N), phosphorus (P), potassium (K), boron (B), and zinc (Zn). Results revealed that the average value of the soil pH significantly (P \u3c 0.05) varied from agroforestry to agricultural land use. Soil OM and N contents were in the medium range in all land use with minor variation, with the highest average OM and N found in grassland (2.87% and 0.14%), followed by agricultural land (2.64% and 0.13%), and agroforestry (2.45% and 0.12%). Soil P showed a significant variation between agroforest (18.99 kg ha−1) and grassland (8.49 kg ha−1). Soil K content was high in grassland (144.44 mg kg−1) and low in agricultural land (120.95 mg kg−1) but was not statistically significant. Micronutrient B was low (0.28–0.35 mg kg−1) and Zn was very low (0.14 mg kg−1). The interpolated soil maps thus generated may assist farmers in identifying the expected nutrient levels for their localities and encourage them to modify their management practices to improve productivity and lift income

Spatial variability of soil properties under different land use in the Dang district of Nepal

Increased nutrient mining, soil erosion, and limited nutrient management has led to declines in soil quality and reduced productivity in many parts of Nepal. A study was conducted in the eastern part of the Dang district of Nepal in 2015 to assess the variability of selected soil properties of three different land use types (agricultural, agroforestry, and grassland) and to map their spatial distribution. A total of 120 soil samples were collected from 0–15 cm depth and analyzed for soil fertility parameters: pH, organic matter (OM), nitrogen (N), phosphorus (P), potassium (K), boron (B), and zinc (Zn). Results revealed that the average value of the soil pH significantly (P \u3c 0.05) varied from agroforestry to agricultural land use. Soil OM and N contents were in the medium range in all land use with minor variation, with the highest average OM and N found in grassland (2.87% and 0.14%), followed by agricultural land (2.64% and 0.13%), and agroforestry (2.45% and 0.12%). Soil P showed a significant variation between agroforest (18.99 kg ha−1) and grassland (8.49 kg ha−1). Soil K content was high in grassland (144.44 mg kg−1) and low in agricultural land (120.95 mg kg−1) but was not statistically significant. Micronutrient B was low (0.28–0.35 mg kg−1) and Zn was very low (0.14 mg kg−1). The interpolated soil maps thus generated may assist farmers in identifying the expected nutrient levels for their localities and encourage them to modify their management practices to improve productivity and lift income

Digital soil mapping in the Bara district of Nepal using kriging tool in ArcGIS

Digital soil mapping has been widely used to develop statistical models of the relationships between environmental variables and soil attributes. This study aimed at determining and mapping the spatial distribution of the variability in soil chemical properties of the agricultural floodplain lands of the Bara district in Nepal. The study was carried out in 23 Village Development Committees with 12,516 ha total area, in the southern part of the Bara district. A total of 109 surface soil samples (0 to 15 cm depth) were collected and analyzed for pH, organic matter (OM), nitrogen (N), phosphorus (P, expressed as P2O5), potassium (K, expressed as K2O), zinc (Zn), and boron (B) status. Descriptive statistics showed that most of the measured soil chemical variables (other than pH and P2O5) were skewed and nonnormally distributed and logarithmic transformation was then applied. A geostatistical tool, kriging, was used in ArcGIS to interpolate measured values for those variables and several digital map layers were developed based on each soil chemical property. Geostatistical interpolation identified a moderate spatial variability for pH, OM, N, P2O5, and a weak spatial variability for K2O, Zn, and B, depending upon the use of amendments, fertilizing methods, and tillage, along with the inherent characteristics of each variable. Exponential (pH, OM, N, and Zn), Spherical (K2O and B), and Gaussian (P2O5) models were fitted to the semivariograms of the soil variables. These maps allow farmers to assess existing farm soils, thus allowing them to make easier and more efficient management decisions and maintain the sustainability of productivity

Climate-smart practices for improvement of crop yields in mid-hills of Nepal

Farming in Nepal mostly represents the hill farming system with the dominance of small-holder farmers. In recent days, farmers in the country are impacted by climate change. Events of surface runoff, landslides, and soil erosions, along with changes in rainfall pattern and intensity have elevated a decline in crop productivity and soil fertility. Considering the situation, a pilot project on Resilient Mountain Village was implemented in Kavrepalanchowk district of Nepal from 2014–2016 with a participatory approach to demonstrate climate-smart practices. These practices include the application of locally prepared bio-fertilizer (named as “jholmal”), green manuring in rice (Oryza sativa L.) and mulching in bitter-gourd (Momordica charantia L.) to determine crop yields compared to farmers’ business as usual practice. The results showed that there was a significant effect of jholmal in rice production during 2015–2016 when compared to farmers\u27 business as usual practice. Likewise, green manuring also showed a significant difference in rice yield compared to farmers’ usual practice in 2015–2016. Bitter-gourd yields were significantly higher in mulching treatment compared to the farmers’ business as usual practice in 2015 and 2016. Rice yield increased by at least 10.1% and 8.1% while using jholmal and green manuring, respectively, whereas bitter-gourd yield increased by 18.1% with mulching practices. Our findings show that farmers have adopted these practices and minimized the use of chemical fertilizers and pesticides, thus moving forward to producing safer food using a climate-friendly approach

Climate-smart practices for improvement of crop yields in mid-hills of Nepal

Farming in Nepal mostly represents the hill farming system with the dominance of small-holder farmers. In recent days, farmers in the country are impacted by climate change. Events of surface runoff, landslides, and soil erosions, along with changes in rainfall pattern and intensity have elevated a decline in crop productivity and soil fertility. Considering the situation, a pilot project on Resilient Mountain Village was implemented in Kavrepalanchowk district of Nepal from 2014–2016 with a participatory approach to demonstrate climate-smart practices. These practices include the application of locally prepared bio-fertilizer (named as “jholmal”), green manuring in rice (Oryza sativa L.) and mulching in bitter-gourd (Momordica charantia L.) to determine crop yields compared to farmers’ business as usual practice. The results showed that there was a significant effect of jholmal in rice production during 2015–2016 when compared to farmers\u27 business as usual practice. Likewise, green manuring also showed a significant difference in rice yield compared to farmers’ usual practice in 2015–2016. Bitter-gourd yields were significantly higher in mulching treatment compared to the farmers’ business as usual practice in 2015 and 2016. Rice yield increased by at least 10.1% and 8.1% while using jholmal and green manuring, respectively, whereas bitter-gourd yield increased by 18.1% with mulching practices. Our findings show that farmers have adopted these practices and minimized the use of chemical fertilizers and pesticides, thus moving forward to producing safer food using a climate-friendly approach

Is conservation agriculture a potential option for cereal-based sustainable farming system in the Eastern Indo-Gangetic Plains of Nepal?

A decline in land and water productivity, increase in the cost of cultivation, and labor-intensive practices are affecting the cereal-based farming system in Nepal, particularly in the Indo-Gangetic Plains (IGP). Conservation agriculture (CA) practices have been found to be the climate-, energy-, and labor-smart and sustainable agricultural production technologies. Sustainable and Resilient Farming System Intensification (SRFSI) has been working since 2014 in response to the sustainability of the cereal-based (rice–wheat and rice–maize) farming in Sunsari and Dhanusha districts of Nepal. This study was conducted to assess the adoption and scaling up of CA in addition to input usage, production, net profit, benefit to cost (B:C) ratio, and labor use of CA practice on average scale land holdings in Sunsari district. The study employed structured questionnaires and key informant surveys as the main data collection tools and project reports were used as secondary data. Results revealed that farmers had several tangible advantages: lower labor utilization per area (71 people day−1 ha−1 as compared to 106 for conventional), lower input cost (NRs. 78,395 ha−1 as compared to 102,727 ha−1), less irrigation with regards to ponding time (50%) as compared to conventional practice, and higher crop productivity (8.11 t ha−1 as compared to 8.08 t ha−1 in rice–wheat and 13.1 t ha−1 as compared to 11.75 t ha−1in conventional rice–maize) farming system through the adoption of CA practices. This study assessed the potential of CA-based practices in a cereal-based cropping system to improve the yields and net profit for sustainability

Is conservation agriculture a potential option for cereal-based sustainable farming system in the Eastern Indo-Gangetic Plains of Nepal?

A decline in land and water productivity, increase in the cost of cultivation, and labor-intensive practices are affecting the cereal-based farming system in Nepal, particularly in the Indo-Gangetic Plains (IGP). Conservation agriculture (CA) practices have been found to be the climate-, energy-, and labor-smart and sustainable agricultural production technologies. Sustainable and Resilient Farming System Intensification (SRFSI) has been working since 2014 in response to the sustainability of the cereal-based (rice–wheat and rice–maize) farming in Sunsari and Dhanusha districts of Nepal. This study was conducted to assess the adoption and scaling up of CA in addition to input usage, production, net profit, benefit to cost (B:C) ratio, and labor use of CA practice on average scale land holdings in Sunsari district. The study employed structured questionnaires and key informant surveys as the main data collection tools and project reports were used as secondary data. Results revealed that farmers had several tangible advantages: lower labor utilization per area (71 people day−1 ha−1 as compared to 106 for conventional), lower input cost (NRs. 78,395 ha−1 as compared to 102,727 ha−1), less irrigation with regards to ponding time (50%) as compared to conventional practice, and higher crop productivity (8.11 t ha−1 as compared to 8.08 t ha−1 in rice–wheat and 13.1 t ha−1 as compared to 11.75 t ha−1in conventional rice–maize) farming system through the adoption of CA practices. This study assessed the potential of CA-based practices in a cereal-based cropping system to improve the yields and net profit for sustainability