Table 4 Data coding
# | Category | Variable | Description |
|---|---|---|---|
1 | Study ID | First author | Mainly last name of the first author |
Publication year | Year the article is published | ||
Numbering | Code for each data point in the study | ||
2 | Name of research group | Research group | Listing the research group that implemented the research and experiment |
3 | Validity of a study | Validity of a study | Internal and external validity of a study that will be assessed as “low”, “moderate” or “high” risk of bias |
4 | Type of paper | Peer-reviewed | If the paper is published in a peer-reviewed journal |
Gray literature | If it is a publication in a website, or a dissertation/thesis, or conference summaries | ||
5 | Study location | Study area | The area where the study has been conducted |
Longitude and latitude | The longitude and the latitude of study area | ||
Country | The country where the study area is located | ||
Type of climate | Classification of climate of the country | ||
Average precipitation | Expressed in mm: Average precipitation in study area | ||
6 | Experimental condition | Condition | Listing if it is randomized replicates or different |
Experimental design | If it is based on open field, greenhouse, or lab | ||
Design characteristics | Plot area, number of plots, or pots (if it is greenhouse or lab experiment) | ||
Experimental setup | Control (without amendment, or with fertilizer or with manure), treatment (with biochar, or fertilizer + biochar, or manure + biochar) | ||
Duration of experiment | Expressed in days | ||
Biochar application rate | Expressed in t/ha | ||
7 | Biochar properties | Feedstock used | The feedstocks used for pyrolysis will be grouped as “woody biomass”, “manure”, “peat-based”, and “agricultural residue” |
Pyrolysis temperature | Expressed in the Celsius scale | ||
Carbon rate | Expressed in g per kg (g/kg) and mass percentage | ||
8 | Soil status | Type of soil | Type of sandy soil and contaminated soil used for the experiment |
Soil sample depth | The minimum and maximum soil depth at which biochar is applied; expressed in cm | ||
Soil treatment before biochar | NPK fertilizer, manure, or other treatments | ||
Soil condition | Soil is tilled or irrigated before the experiment | ||
9 | Ecosystem services (ESS) | Measurement | List of ESS measured in the study |
Measurement unit | Unit used to measure ESS | ||
10 | Changes in ecosystem services | Control (without amendment, or with manure, or with fertilizer) | Means, SD, correlation, OR t-value OR F-score |
Treatment (with biochar only, or with manure + biochar, or fertilizer + biochar) | Means, SD, correlation, OR t-value OR F-score |