Seasonal dynamics of soil CO₂ emissions from different semi-arid land-use systems

ABSTRACT

Soil carbon dioxide (CO₂) fluxes are a critical component in understanding carbon sequestration. In sub-Saharan Africa, empirically measured CO₂ emissions data from diverse land-use systems is limited. Soil CO₂ emission rates were measured in the Limpopo Province, South Africa for 12 months at two-week intervals in natural systems (forest and shrubland) and commercially managed orchards (avocado and citrus) to establish seasonal dynamics of soil CO₂ emissions across these land-use systems. The results showed a variation in emission rates with the variation depending on the season. In the spring and winter, soil CO₂ emission rates in citrus were four times higher than in the shrubland due to higher moisture levels. However, in the summer season, the forest emission rates were 40% higher than in citrus due to higher soil organic carbon content. Organic carbon stocks were higher in the forest (1.19 kg/m²) compared to the other land uses. This study revealed differences in soil CO₂ emission rates among land-use systems, with the cumulative amount of CO₂ emitted over a 12-month period following the order: forest (39.3 tons/ha) > citrus (36.1 tons/ha) > shrubland (28.1 tons/ha) > avocado (26.9 tons/ha). Thus, understanding the emission patterns from various ecosystems can inform strategies for mitigating greenhouse gas emissions.

KEYWORDS:

• Carbon stocks
• orchards
• forest
• soil temperature
• soil moiture

Acknowledgements

The authors would like to acknowledge the Risk and Vulnerability Science Centre, University of Limpopo for funding this research. The authors also acknowledge community in the Lataba catchment, Mahela Group and ZZ2 for allowing the research on their farms.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Water Research Commission: (Project No. C2019/2020-00166).

Notes on contributors

Lawrence Munjonji

Lawrence Munjonji is Senior Lecturer in the Department of Soil Science, Faculty of AgriSciences, University of Stellenbosch.

Hlengiwe Ntuli Innocentia

Hlengiwe Ntuli Innocentia is Soil Science MSc Student in the Department of Soil Science, Plant Production and Agricultural Engineering, University of Limpopo.

Kingsley Kwabena Ayisi

Kingsley Kwabena Ayisi is Professor and Manager of the Risk and Vulnerability Science Center, University of Limpopo.

Phesheya Dlamini

Phesheya Dlamini is a Professor in the Department of Soil Science, Plant Production and Agricultural Engineering, University of Limpopo.

Kabisheng Emmanuel Mabitsela

Kabisheng Emmanuel Mabitsela holds an MSc in Soil Science and is Research Assistant at the Risk and Vulnerability Science Center, University of Limpopo.

Carol Mmapula Lehutjo

Carol Mmapula Lehutjo holds an MSc in Agronomy and is a Research Assistant at the Risk and Vulnerability Science Center, University of Limpopo.

Phumlani Sabelo Magnificent Zwane

Phumlani Sabelo Magnificent Zwane holds an MSc in Geography and Environmental Science and is Technician at Sol Platjie University.