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Emissions of CO2 from the soil are the second‐largest component of the global carbon cycle, which has altered the climate and led to climate change. The main aim of this research was to evaluate the direct impact of climate and soil management systems on soil carbon emissions. Thus, CO2 emissions were measured from maize fields located in two different climate regions (continental and semi‐arid). The experimental design involved two different soil management systems (conventional tillage [CT], non‐tillage [NT]) from two different sites (Debrecen [Hungary], Karaj [Iran]). The results showed that total CO2 emission from the cultivated system (CT) was higher than that from the non‐cultivated (NT) one, regardless of the climate region. However, CO2 emissions from agricultural soil in a humid region are significantly different (p < .05) from semi‐arid regions, which clearly emphasizes the role of climate conditions in the CO2 emission processes. However, the general linear model reveals that all studied variables (soil management systems, date of measurement, soil temperature, soil water content) had a significant (p < .05) effect on soil carbon emission, where the explained variance was 0.866. The findings of this research stress the importance of NT in CO2 mitigations on the farm scale. However, the output could help to draw up mitigation strategies to minimize the total greenhouse gas emissions from agricultural soil in both countries.

Agricultural activity is the major anthropogenic source of nitrous oxide (N2O) emissions from terrestrial ecosystems. Conservation agriculture including crop residue management can play a key role in enhancing soil resilience to climate change and mitigating N2O emissions. We investigated the effects of crop residue rates, including 100 % (R100), 50 % (R50), and residue removal (R0), on N2O emissions in corn-wheat rotation under conventional (CT) and no-tillage (NT) systems. The key factors evaluated affecting N2O emissions included soil temperature, soil moisture, soil ammonium, and soil nitrate concentrations. Results showed that the N2O emissions increased with the increasing rate of residue under both CT and NT systems. Both R100 and R50 significantly ( p < .05) increased the N2O emissions compared to R0 during the annual rotation cycle. Soil moisture and mineral nitrogen (ammonium and nitrate) were the main driving factors that stimulated N2O emission in both CT and NT systems. In the NT and CT systems, cumulative N2O emissions showed a significant increase with R50 (+75.5 % in NT, +36.5 % in CT) and R100 (+134 % in NT, +40 % in CT) as compared to R0. Furthermore, no significant differences were found between R100 and R50 in the CT system, while in the NT system significant increases were observed for R100 compared to R50. Overall, our study justified as a first approach only during the first year that crop residue removal led to decreased N2O emissions under semi-arid conditions. However, due to the deteriorating impact of crop residue removal on crop productivity and soil C sequestration, this management method cannot be considered a sustainable agronomic practice. We suggest long-term studies to determine the appropriate rate of postharvest crop residue to achieve less N2O emissions and climate-friendly agricultural practices.

The intensification of specific land management operations (tillage, herbicide, etc.) is increasing land degradation and contributing to ecosystem pollution. Mulches can be a sustainable tool to counter these processes. This is particularly relevant for rural areas in low-income countries where agriculture is a vital sector. In this research, the environmental impact of different rates of wheat residues (no residues, 25, 50, 75, and 100%) in corn silage cultivation was evaluated using the life cycle assessment (LCA) method under conventional tillage (CT) and no-tillage (NT) systems in a semi-arid region in Karaj, Iran. Results showed that in both tillage systems, marine aquatic ecotoxicity (ME) and global warming potential (GWP) had the highest levels of pollution among the environmental impact indicators. In CT systems, the minimum (17,730.70 kg 1,4-dichlorobenzene (DB) eq.) and maximum (33,683.97 kg 1,4-DB eq.) amounts of ME were related to 0 and 100% wheat residue rates, respectively. Also, in the CT system, 0 and 100% wheat residue rates resulted in minimum (176.72 kg CO2 eq.) and maximum (324.95 kg CO2 eq.) amounts of GWP, respectively. However, in the NT system, the 100% wheat residue rate showed the minimum amounts of ME (11,442.39 kg 1,4-DB eq.) and GWP (120.21 kg CO2 eq.). Also, in the NT system, maximum amounts of ME (17,174 kg 1,4-DB eq.) and GWP (175.60 kg CO2 eq.) were observed with a zero wheat residue rate. On-farm emissions and nitrogen fertilizers were the two factors with the highest contribution to the degradation related to environmental parameters at all rates of wheat residues. Moreover, in the CT system, the number of environmental pollutants increased with the addition of a higher wheat residue rate, while in the NT system, increasing residue rates decreased the amount of environmental pollutants. In conclusion, this LCA demonstrates that the NT system with the full retention of wheat residues (100%) is a more environmentally sustainable practice for corn silage production. Therefore, it may be considered one of the most adequate management strategies in this region and similar semi-arid conditions. Further long-term research and considering more environmental impact categories are required to assess the real potential of crop residues and tillage management for sustainable corn silage production.

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