Lime soils when required
System: Arable Crops
Mainly applicable for: Acidic soils
Not applicable or effective for: Neutral or alkaline soils
Description
Lime is a calcium or magnesium containing mineral applied on soils to reduce soil acidity by increasing soil pH, in order to maintain or improve soil quality in terms of its structure and biochemical function. The material can come in different forms, especially calcium carbonate (CaCO3) and magnesium carbonate (MgCO3) are used.
Mechanism of effect
Liming raises soil pH, which can reduce nitrous oxide (N₂O) emissions on the farm in acidic soils by improving the completeness of the denitrification process (the transformation of NO3- into N2). At low pH, denitrifying bacteria produce more N₂O because the enzymes converting N₂O into harmless nitrogen gas (N₂) are inhibited. By increasing pH, liming allows bacteria to fully convert N₂O to N₂, lowering overall on-farm N₂O emissions. Liming also enhances soil microbial activity and nutrient availability, improving nutrient cycling and potentially increasing crop yields and carbon input from crop residues to the soil. This can reduce the need for synthetic nitrogen fertilizers, further decreasing N₂O emissions on the farm.
Increased CO2 emissions from the soil after liming is expected (due to chemical decomposition of CaCO₃ in the soil ) but this component is generally small and there has been contradictory evidence. Nonetheless, liming increases upstream CO₂ emissions due to lime production and transport.
Hence, while liming raises upstream CO₂ emissions, these may be partly offset by reduced on-farm N₂O emissions, improved fertiliser use efficiency, higher yields and possible increased C inputs. If liming enables lower synthetic nitrogen fertiliser doses, it also reduces CO₂ emissions linked to fertiliser production.
Reference situation
Acidic soil without liming
Legend
| ● – Small effect (<5%) | ● – small unfavourable effect (<5%) | o – No effect |
| ●● – Medium effect (5-20%) | ●● – large unfavourable effect (>=5%) | N/A – effect unknown |
| ●●● – Large effect (>20%) | ● – ● – Variable effect (depending on farm characteristics or way/level of implementation) |
Effect on total greenhouse gas (GHG) emissions (kg CO2-eq)
| Mean effect and range in kg CO2-equivalents | per kg product | ||
| Mean | min-max | Level of evidence | |
| Lime soils | ●● | ●–●● | Medium |
Effect per emission source
| Mean effect on emission from | Soil (per ha) | Inputs | Energy use | |
| N20 | min-max | CO2 | CO2 | |
| Lime soils | ●● | ●–●●● | ● | ● |
*risk of an adverse effect (see ’cause of variable or unfavourable effect’)
Explanation of variable effect
Lime soils
The effect depends on soil pH, nitrogen source, type of lime, and overall nutrient management practices. In general liming will improve soil quality, which might have positive effects on crop yields. If biomass production increases it might increase carbon inputs to the soil, but with the increased pH also the decomposition rate might increase. In literature variable effects of liming on SOC are found.
Overall, CaCO₃ production is typically less energy-intensive than Ca(OH)₂ production, although upstream impacts vary with the transformation chain, limestone characteristics, local practices, and industrial processes.
| Literature references | Lime soils |
|---|---|
| Hijbeek et al., 2021 | Liming agricultural soils in Western Kenya: Can long-term economic and environmental benefits pay off short term investments? |
| Kunhikrishnan et al., 2016 | Functional Relationships of Soil Acidification, Liming, and Greenhouse Gas Flux |
| Holland et al., 2018 | Liming impacts on soils, crops and biodiversity in the UK: A review |
| Zhang et al. 2022 | Liming modifies greenhouse gas fluxes from soils: A meta-analysis of biological drivers |
| Beillouin et al., 2023 | A globalmeta-analysis of soil organic carbon in the Anthropocene |
| Wang, Y., et al., 2021 | Potential benefits of liming to acid soils on climate change mitigation and food security. Global Change Biology, 27(12), 2807-2821 |
| Hui-Min et al., 2022 | Liming modifies greenhouse gas fluxes from soils: A meta-analysis of biological drivers |
| Hénault et al., 2019 | Management of soil pH promotes nitrous oxide reduction and thus mitigates soil emissions of this greenhouse gas |
| Rousset et al., 2024 | Surprising minimisation of CO2 emissions from a sandy loam soil over a rye growing period achieved by liming (CaCO3) |
| Hénault et al., 2020 | Evaluation du potentiel d’atténuation des émissions de GES par le chaulage des sols en France et proposition d’une méthodologie de prise en compte dans les inventaires nationaux d’émissions |