Purpose Biogas residues, digestates, contain valuable nutrients and are therefore suitable as agricultural fertilizers. However, the application of fertilizers, including digestates, can enhance greenhouse gas (GHG) emissions. In this study different processes and post-treatments of digestates were analyzed with respect to triggered GHG emissions in soil. Methods In an incubation experiment, GHG emissions from two contrasting soils (chernozem and sandy soil) were compared after the application of digestate products sampled from the process chain of a food waste biogas plant: raw substrate, digestate (with and without bentonite addition), digestates after separation of liquid and solid phase and composted solid digestate. In addition, the solid digestate was sampled at another plant. Results The plant, where the solid digestate originated from, and the soil type influenced nitrous oxide (N2O) emissions significantly over the 38-day experiment. Composting lowered N2O emissions after soil application, whereas bentonite addition did not have a significant effect. High peaks of N2O emissions were observed during the first days after application of acidified, liquid fraction of digestate. N2O emissions were strongly correlated to initial ammonium (NH4+) content. Conclusion Fertilization with dewatered digestate (both fractions) increased N2O emission, especially when applied to soils high in nutrients and organic matter.

BACKGROUND AND OBJECTIVES: Anthropogenic activities in livestock sectors are responsible for emitting substantial amounts of greenhouse gases, including carbon dioxide, methane, and dinitrous oxide, into the atmosphere, thereby contributing to climate change. The impact of these gases can be reduced through effective mitigation and adaptation efforts. This study aimed to estimate the livestock greenhouse gas emissions in Minahasa District, Indonesia; identify the greenhouse gas sources and distribution; and provide feasible mitigation options.METHODS: This study used mixed methods to collect primary and secondary data from breeders and stakeholders in the Minahasa Regency. Interviews and questionnaires were also conducted, and the local government office provided secondary data. Breeders from various groups who lived in 25 different districts participated in this study, and the data analysis techniques used a Tier 1 model to process the data. The participants were included in focus group discussion activities for qualitative data collection to formulate potential mitigation strategies.FINDINGS: The livestock sector emitted 48.83 gigagrams of carbon dioxide equivalent in 2021, and this was expected to increase by 24.98 percent in 2022, resulting in a total emission of 65.09 gigagrams of carbon dioxide equivalent. The sector also experienced a steady rise in emissions since 2010, with an average annual increase of 3.17 percent. The emissions were primarily composed of methane and dinitrous oxide, which accounted for 64.68 and 0.41 gigagrams carbon dioxide equivalent, respectively. In terms of livestock greenhouse gas distribution, the Sonder District produced 13.98 percent of the emission at 8.77 gigagrams of carbon dioxide equivalent. The main emissions resulted from methane manure management and enteric fermentation at 84.53 and 15.23 percent (7.41 and 1.34 gigagrams of carbon dioxide equivalent, respectively), while the remaining was composed of dinitrous oxide gas. In Kawangkoan District, the greenhouse gas emissions were dominated by methane from enteric fermentation and manure management, which accounted for 15.23 and 20.05 percent (5.63 and 1.43 gigagrams of carbon dioxide equivalent). In addition, the total emission accounted for 11.33 percent at 7.11 gigagrams of carbon dioxide equivalent.CONCLUSION: The study produced an estimate of greenhouse gases from the livestock sector in the Minahasa Regency. During the studied period (2010-2022), the total greenhouse gas emissions exhibited an average annual increase of 3.17 percent. In 2022, the emissions consisted of methane and dinitrous oxide, with respective contributions of 99.38 percent per year and 0.62. Based on the spatial mapping, the Sonder District produced the largest cumulative emissions, primarily driven by emissions from animal waste management. Conversely, the Kawangkoan District dominated emissions stemming from the enteric fermentation of ruminant animals. These findings imply that all stakeholders in the Minahasa Regency should prioritize efforts to implement adaptation and mitigation programs to reduce these impacts.

The link between economic growth and environmental pollution has been extensively and statistically analyzed over the past two decades. The present study investigates the non-linear effects of variables affecting greenhouse gas emissions. To this aim, a Time Varying Parameters Vector Autoregression (TVP-VAR) model has developed using annual data which covers the period 1972-2018. Moreover, the associated Impulse Response Function (IRF) of the selected influential variables such as GDP (oil, without oil) and electricity consumption on the greenhouse gas emissions (carbon dioxide) has computed. Findings revealed the nonlinear impact of GDP on the greenhouse gas emission, so that until 2002 it had a positive effect on reducing greenhouse gas emission,whereas, from 2002 onwards it had a negative impact and led to escalating the greenhouse gas expansion. Besides, the positive shock of electricity consumption and GDP (without oil) on greenhouse gas emissions during the entire period was positive. Furthermore, the emission of greenhouse gas on itself is positive throughout the study period.

Excessive consumption of energy in Iran resulted greenhouse gas emissions and related risks to the environment and human health. The aim of this study was to evaluate the effects of tillage and cultivation of wheat (including conventional farming, reduced tillage and direct seeding) on energy consumption and environmental pollution in the Kalpoosh region of Semnan province. Data were collected through interviews in 30 typical fields of wheat production. Data were analyzed with regard to inputs consumption, inputs energy and greenhouse gas emissions from the consumed energy and tillage method. Total inputs energy from the consumed inputs varied between 13900 to 18713 MJ ha-1. Results indicated that in conventional method, fuel consumption had the most share of energy input (37.8 % of total) followed by Nitrogen (26.5%) and seed (17.4%), respectively. Nitrogen had the most share of energy input in reduced tillage (31.7%) and direct seeding (35.7%). Maximum and minimum of greenhouse gas emissions (CO2, CH4 and N2O) were related to conventional seeding (11713 kg equivalent CO2 ha-1) and direct seeding (2721 kg equivalent CO2 ha-1.), respectively. Wheat yield differences in three methods wasn’t significant, maximum and minimum of wheat yield related to reduced tillage, direct seeding, respectively. Maximum and minimum of economical productivity belonged to direct seeding (0.21) and conventional tillage (0.16), respectively. It can be concluded that using conservation tillage (reduced tillage and direct seeding), without a significant decrease in the yield of wheat, reduced fuel consumption, energy and greenhouse gas emissions, and increased energy efficiency and economical productivity.

The goal followed in the present study was to analyze the GreenHouse Gas (GHG) emissions in pasta production. Data for the study was collected from durum wheat production farms from three provinces, Iran. Data of soil properties, transportation as well as and pasta factory production stages were collected and analyzed, using SimaPro Software, Ecoinvent data base and Global Warming Potential (GWP) for 100 year method. EPIC model was used to calculate GHG emissions of land use change. Results indicated the average greenhouse gas emission related to one kg of pasta production was 2.64 kg CO2-eq. Among the different sources of emissions, land use change and fuel consumption for agricultural operations constituted the main contributors to total GWP of pasta production.