Coal char affects soil pH to reduce ammonia volatilization from sandy loam soil

Abstract

Ammonia (NH 3) volatilization loss adversely affects N availability in soil-plant systems, reduces crop yield, and negatively impacts environment. Char (coal combustion residue), which contains up to 293 g kg −1 total C by weight, has been shown to reduce NH 3 volatilization due to its considerably high surface area and cation exchange capacity. The NH 3 loss can be greatly affected by a shift in soil pH or urea hydrolysis. A 21-d laboratory study was conducted to evaluate the effects of char on soil pH, N transformations, and subsequent NH 3 volatilization in sandy loam soil. Two char rates (0 and 13.4 Mg C ha −1) and two urea rates (0 and 200 kg N ha −1) were mixed in soil in four 2-way combinations with four replications of each. There were 11 sets of all treatment combinations and each set was analyzed for soil moisture, pH, NH 3 volatilization, and residual N (urea, NH 4 , and NO 3) every other day for 3 wk. Char application reduced cumulative NH 3 loss in the fertilized treatment. Reduction in NH 3 loss due to char addition was evidenced by greater residual NH 4-N on certain days in treatments with char compared to treatments without char. Char did not affect urea hydrolysis process but it lowered soil pH in the fertilized treatments in the first week. This study supported our hypothesis that char altered soil pH and thereby reduced NH 3 volatilization loss from the fertilized soil. Abbreviations: CEC, cation exchange capacity. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Coal char effects on soil chemical properties and maize yields in semi‐arid region

“…A significant decrease in soil pH with addition of char up to 13.4 Mg C ha −1 compared with the control could be due to soil dilution effect with char (Thomas, 1996). Similar results were observed in the incubation study that reported reduction in soil pH with the char applied at 13.4 Mg C ha −1 in urea‐fertilized sandy loam compared with no char treatments (Panday et al., 2020b). Lai et al.…”

Evaluating coal char as an alternative to biochar for mitigating nutrient and carbon loss from manure‐amended soils: Insights from a greenhouse experiment

“…The relatively high C content among different types of coal combustion residues makes this char also valuable for efforts to restore soil C storage in degraded soils (Blanco‐Canqui et al., 2020). However, to the best of our knowledge, data on this char material to improve agricultural soil are limited to four published studies (Blanco‐Canqui et al., 2020; Panday, Mikha, Collins, et al., 2020; Panday, Mikha, & Maharjan, 2020; Panday et al., 2021). From a 30‐d column experiment Panday, Mikha, Collins, et al.…”

Ammonia volatilization from fertilizer sources on a loam soil in Idaho

“…Although there are many positives of urea fertilizer, it is well reported that urea is highly susceptible to NH 3 volatilization losses when left on the soil surface (Goos & Guertal, 2019; Pan et al., 2016; Rochette et al., 2013). These NH 3 volatilization losses affect crop yields, fertilizer N use efficiency, environmental and health issues, and indirectly N 2 O emissions (Panday et al., 2020). The magnitude of NH 3 volatilization is greatly affected by soil pH, soil texture, and environmental conditions.…”

“…The magnitude of NH 3 volatilization is greatly affected by soil pH, soil texture, and environmental conditions. Ammonia gas is preferentially formed as pH increases into the alkaline range, where added urea dissolves, hydrolyzes to form NH 4 or NH 3 , and increases pH due to the nature of the chemical reaction (Panday et al., 2020). High pH alkaline calcareous and loamy agricultural soils in the western United States (e.g., Idaho) can be more conducive to NH 3 volatilization (Dari, Rogers, & Walsh, 2019).…”

“…These sources exhibit reduced potential for NH 3 volatilization losses due to a lack of pH increase as well as a reduced amount of N in the NH 4 form for AN (Ti et al., 2019; Woodley et al., 2020). However, AS and AN are typically more expensive (USDA‐NRCS, 1999), less accessible, and may even be restricted (e.g., AN) (Panday et al., 2020). Larger quantities of AS fertilizer are needed for comparable N application as compared with urea due to the lower percentage of N (21%).…”