Effects of activated charcoal and tannin added to compost and to soil on carbon dioxide, nitrous oxide and ammonia volatilization

Abstract

Given high mineralization rates of soil organic matter addition of organic fertilizers such as compost and manure is a particularly important component of soil fertility management under irrigated subtropical conditions as in Oman. However, such applications are often accompanied by high leaching and volatilization losses of N. Two experiments were therefore conducted to quantify the effects of additions of activated charcoal and tannin either to compost in the field or directly to the soil. In the compost experiment, activated charcoal and tannins were added to compost made from goat manure and plant material at a rate of either 0.5 t activated charcoal ha -1 , 0.8 t tannin extract ha -1 , or 0.6 t activated charcoal and tannin ha -1 in a mixed application. Subsequently, emissions of CO 2 , N 2 O, and NH 3 volatilization were determined for 69 d of composting. The results were verified in a 20-d soil incubation experiment in which C and N emissions from a soil amended with goat manure (equivalent to 135 kg N ha -1 ) and additional amendments of either 3 t activated charcoal ha -1 , or 2 t tannin extract ha -1 , or the sum of both additives were determined. While activated charcoal failed to affect the measured parameters, both experiments showed that peaks of gaseous CO 2 and N emission were reduced and/or occurred at different times when tannin was applied to compost and soil. Application of tannins to compost reduced cumulative gaseous C emissions by 40% and of N by 36% compared with the non-amended compost. Tannins applied directly to the soil reduced emission of N 2 O by 17% and volatilization of NH 3 by 51% compared to the control. However, emissions of all gases increased in compost amended with activated charcoal, and the organic C concentration of the activated charcoal amended soil increased significantly compared to the control. Based on these results, tannins appear to be a promising amendment to reduce gaseous emissions from composts, particularly under subtropical conditions.

Gaseous carbon and nitrogen losses during composting of carbonized and un‐carbonized agricultural residues in northern Ghana

“…Cumulative CO 2 ‐C emissions during composting varied between 6 and 11% of the initial C and were lower than the range of 15 and 44% reported by Jordan et al () for manure composting. This may be explained by the fact that our measurements captured only surface emissions, but not the bulk in the whole bin compared to the approach of the previous authors who composted in 80L PVC buckets.…”

“…The reference area was up‐scaled from the cuvette surface to one m 2 (mg m −2 h −1 ). To calculate accumulated gaseous losses from the composting process, data of each measurement were multiplied by the time span to the next measurement event and summed up to the end of the composting period ( Jordan et al, )…”

“…The reference area was upscaled from the cuvette surface to one m 2 (mg m -2 h -1 ). To calculate accumulated gaseous losses from the composting process, data of each measurement were multiplied by the time span to the next measurement event and summed up to the end of the composting period (Jordan et al, 2015) Data were analysed using a mixed model (PROC MIXED) in SAS (SAS Institute Inc., Carey, NC, USA). Data residuals were tested for the assumptions of normality using the Shapiro-Wilk test and graphical checks.…”

“…This region is characterised by inherently low cation exchange capacity (CEC) resulting from ancient weathering of the parent rocks and declining soil organic matter (Agegnehu et al, 2015) due to rapid turnover rates of soil organic carbon under cultivation (Bationo and Buerkert, 2001). The addition of organic matter to these tropical soils is, thus, of particular importance to soil fertility (Jordan et al, 2015). Urban and peri-urban agriculture (UPA) compliments rural agriculture, supplying fresh vegetables for the increasing urban population (Predotova et al, 2011).…”

Soil Gaseous Emissions and Partial C and N Balances of Small-Scale Farmer Fields in a River Oasis of Western Mongolia

“…In rare cases of negative NH 3 and N 2 O emission rates, values were set to zero [20]. A linear increase of gas concentrations in the chamber was assumed [38], which was supported by strong bivariate Pearson correlations between gas concentration and accumulation time [39]. The area covered by the chamber was upscaled to one hectare (g ha −1 h −1 ).…”