Table 1 Eligibility criteria used in the systematic map
Key element | Inclusion | Exclusion |
|---|---|---|
Eligible Subject | Arable farmland in temperate climates defined as fully humid and summer dry, i.e., Cfa, Cfb, Cfc, Csa, Csb, Cs in Köppen–Geiger classification (Kottek et al. [24]). Peatlands were included only when being used for agricultural purposes | Crops that are primarily found in tropical regions (e.g., rice, sugarcane, bananas) were excluded as these were considered as not relevant to the stakeholders. Grasslands, pastures, forests, and plantations were excluded, although grasses grown as bioenergy crops were included |
Eligible intervention | Any farmland management practice applied to the crop or the soil, and that could be applied to entire fields. This included, for example: fertilisation; addition of amendments (e.g. lime); crop rotations; soil tillage | Practices such as buffer strips that are not feasible as whole-field interventions were excluded. Comparisons of different starting soil types/contents (e.g. phosphorus concentration, moisture content) were excluded if no actual intervention was present in the study. Land use change studies were excluded, i.e. where land is changed from arable to another type of use e.g. from arable to urban development |
Eligible comparators | Different levels of a management practice or an absence of a particular practice, either spatially (nearby control fields or plots) or temporally (i.e. before a management practice was initiated) | Studies without a comparator at the intervention level were excluded. Studies that compared different crops (e.g., wheat vs corn) with the same intervention were excluded |
Eligible outcomes | Fluxes of GHGs (CO2, CH4, N2O) | Precursors (e.g., HONO) were excluded |
Eligible study designs | Any observational or manipulative experimental study | Modelling studies, greenhouse or laboratory studies and ex situ experiments were excluded |
Eligible languages | Attempts to include articles in a range of languages in addition to English were made. Articles judged as eligible but in other languages are listed in additional information 3 but were not included in data extraction | Â |