Although herbicides are essential for global agriculture and controlling weeds, they impact soil microbial communities and CO2 emissions. However, the effects of herbicides, tillage systems, and nitrogen fertilisation on CO2 emissions under different environmental conditions are poorly understood. This review explores how various agricultural practices and inputs affect CO2 emissions and addresses the impact of pest-management strategies, tillage systems, and nitrogen fertiliser usage on CO2 emissions using multiple databases. Key findings indicate that both increased and decreased tendencies in greenhouse gas (GHG) emissions were observed, depending on the herbicide type, dose, soil properties, and application methods. Several studies reported a positive correlation between CO2 emissions and increased agricultural production. Combining herbicides with other methods effectively controls emissions with minimal chemical inputs. Conservation practices like no-tillage were more effective than conventional tillage in mitigating carbon emissions. Integrated pest management, conservation tillage, and nitrogen fertiliser rate optimisation were shown to reduce herbicide use and soil greenhouse gas emissions. Fertilisers are similarly important; depending on the dosage, they may support yield or harm the soil. Fertiliser benefits are contingent on appropriate management practices for specific soil and field conditions. This review highlights the significance of adaptable management strategies that consider local environmental conditions and can guide future studies and inform policies to promote sustainable agriculture practices worldwide.

Crop–weed competition markedly reduces cereal yield. Integrative weed management approaches, involving the use of humic acid (HA) and seaweed extract (SWE), have gained attention as herbicide efficacy declines and environmental concerns grow. However, potential synergistic effects between HA and SWE have not yet been investigated. We evaluated the effects of HA, SWE, and their combination (HA+SWE) on the growth, yield, and competitive ability of cereals against wild weed beets (Beta vulgaris L.). A single-season field experiment was conducted using a split-plot design within a randomised complete block to assess the effects of treatment amendments on wheat, barley, and oats. The results showed that HA and HA+SWE organic amendments consistently improved grain yield and biomass across crop species. SWE responses varied across species, indicating species-dependent sensitivity. In addition, HA enhanced barley weed suppression, highlighting its dual roles in improving crop vigour and reducing weed proliferation. In contrast, SWE modestly increased spike length in oats, emphasising its effect on crop growth characteristics. Overall, these preliminary findings support targeted biostimulant use to enhance cereal yield and integrate weed management into sustainable cropping systems.