Soil carbon dynamics in temperate urban and peri-urban agriculture
Data files
Sep 30, 2026 version files 9.91 KB
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README.md
4.34 KB
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soil_flux_parameters_crop_diversity.csv
5.58 KB
Abstract
Urban and peri-urban agriculture (UPA) is an increasingly popular approach to support regional food systems. UPA can reduce greenhouse gas emissions via reduced food miles and through soil and crop management. Yet, UPA systems lack data on soil carbon (C) dynamics and key factors that control C fluxes. To address this, we examined the role of soil biochemical parameters and crop diversity on soil C dynamics in 17 existing urban and peri-urban community farms and allotment gardens, categorized into new, intermediate, and established sites, in the Greater Toronto Area, Canada. Soil CO2 emissions were measured in situ using a LI-6800 closed chamber system, and soil properties and crop diversity were evaluated within 1x1m plots (n = 102). Soil CO2 efflux was significantly lower in new sites and soil available phosphorus was significantly higher in established sites, but all other soil biochemical parameters were similar. In established sites, soil CO2 efflux was negatively correlated with soil organic matter. Soil microbial composition differed between new, intermediate, and established sites. Crop diversity did not impact soil CO2; however, soil total C was significantly higher in diverse systems than in monocultures. We show that older UPA systems can store upwards of 76 Mg of total C per ha, in line with average C storage in broad-acre rural agriculture. Our findings show detectable and important differences in soil fluxes, microbial communities, and crop diversity in newer versus older UPA systems. And our results inform management strategies for improving soil quality in and around cities.
Dataset DOI: 10.5061/dryad.dncjsxmg2
Description of the data and file structure
Urban and peri-urban agriculture (UPA) is an increasingly popular approach to support regional food systems. UPA can reduce greenhouse gas emissions via reduced food miles and through soil and crop management. Yet, UPA systems lack data on soil carbon (C) dynamics and key factors that control C fluxes. To address this, we examined the role of soil biochemical parameters and crop diversity on soil C dynamics in 17 existing urban and peri-urban community farms and allotment gardens, categorized into new, intermediate, and established sites, in the Greater Toronto Area, Canada. Soil CO2 emissions were measured in situ using a LI-6800 closed chamber system, and soil properties and crop diversity were evaluated within 1x1m plots (n = 102). To measure crop diversity, the number of crop species and frequency were recorded. Soil samples were collected adjacent to the chamber and brought to the Soil Fertility and Plant Nutrition Analytical Laboratory at UTSC for analyses. Soil organic matter was measured using a muffle furnace (through “loss on ignition”). Soil active C, total C, total nitrogen, and available phosphorus were measured using elemental analysis and spectrophotometry.
Files and variables
Files
| File Name | Description |
|---|---|
| soil_flux_parameters_crop_diversity.csv | The dataset includes measurements of soil CO2 efflux, total carbon (C), total nitrogen, soil organic matter, active C, available phosphorus, and a crop diversity metric (Shannon Diversity Index) collected from 17 existing urban and peri-urban community farms and allotment gardens, categorized into new, intermediate, and established sites, in the Greater Toronto Area, Canada. |
Variables
| Variable | Description | Unit |
|---|---|---|
| Site | Number of sites: 1 to17 | Count |
| Age | Age category: A = Established, B = Intermediate, C = New | Category |
| Rep | Number of replications: 1 to 6 | Count |
| CE | CO2 efflux rate | µmol m⁻² s⁻¹ |
| Total_C | Total carbon concentration | % |
| Total_N | Total nitrogen concentration | % |
| SOM | Soil organic matter concentration | % |
| POXC | Active carbon concentration | mg kg⁻¹ |
| Available P | Available phosphorus concentration | mg kg⁻¹ |
| SI | Shannon Diversity Index | None |
Abbreviations
CO2 = carbon dioxide
Missing Values
Missing values that were removed as outliers are represented as NA in the data file.
Code/software
The provided data file is in CSV format, which can be viewed in R or using any spreadsheet software. Data were analyzed and visualized in R version 4.6.1 (R Core Team, 2026). The key packages used included EnvStats, lme4, lmerTest, car, emmeans, glmmTMB, vegan, ggplot2, cowplot, and patchwork.