Soil organic carbon, total nitrogen stocks and CO2 emissions in top- and subsoils with contrasting management regimes in semi-arid environments

Chukwuebuka C Okolo; Girmay Gebresamuel; Amanuel Zenebe; Mitiku Haile; Jephter E Orji; Chinyere B Okebalama; Chinedu E Eze; Emmanuel Eze; Peter N Eze

doi:10.1038/s41598-023-28276-x

Soil organic carbon, total nitrogen stocks and CO₂ emissions in top- and subsoils with contrasting management regimes in semi-arid environments

Sci Rep. 2023 Jan 20;13(1):1117. doi: 10.1038/s41598-023-28276-x.

Authors

Chukwuebuka C Okolo^{1

2

3

4

5}, Girmay Gebresamuel⁶, Amanuel Zenebe^{6

7}, Mitiku Haile⁶, Jephter E Orji⁸, Chinyere B Okebalama^{9

10}, Chinedu E Eze^{11

12}, Emmanuel Eze^{13

14

15}, Peter N Eze¹⁶

Affiliations

¹ Department of Land Resources Management and Environmental Protection, Mekelle University, P. O. Box 231, Mekelle, Ethiopia. okolochukwuebuka@gmail.com.
² Institute of Climate and Society, Mekelle University, P. O. Box 231, Mekelle, Ethiopia. okolochukwuebuka@gmail.com.
³ Department of Natural Resources Management, Jimma University, P. O. Box 378, Jimma, Ethiopia. okolochukwuebuka@gmail.com.
⁴ Department of Geoscience, Geo-Biosphere Interaction Group, Eberhard Karls University Tübingen, 72076, Tübingen, Germany. okolochukwuebuka@gmail.com.
⁵ Department of Earth and Environmental Science, Botswana International University of Science and Technology, Private Bag 16, Palapye, Botswana. okolochukwuebuka@gmail.com.
⁶ Department of Land Resources Management and Environmental Protection, Mekelle University, P. O. Box 231, Mekelle, Ethiopia.
⁷ Institute of Climate and Society, Mekelle University, P. O. Box 231, Mekelle, Ethiopia.
⁸ Department of Agriculture, Alex Ekwueme Federal University Ndufu-Alike, Ikwo, Nigeria.
⁹ Department of Soil Science, Faculty of Agriculture, University of Nigeria Nsukka, Nsukka, Nigeria.
¹⁰ Ruhr University Bochum, Bochum, Germany.
¹¹ Department of Agronomy, Michael Okpara University of Agriculture, Umudike, Nigeria.
¹² Smithsonian Tropical Research Institute, Panama City, Panama.
¹³ Faculty of Chemistry and Earth Sciences, Institute of Geography, University of Heidelberg, Heidelberg, Germany.
¹⁴ Department of Geography ‑ Research Group for Earth Observation (rgeo), UNESCO Chair On World Heritage & Biosphere Reserve Observation and Education, University of Education Heidelberg, Heidelberg, Germany.
¹⁵ Geographical and Environmental Education Unit, Department of Social Science Education, University of Nigeria, Nsukka, Nigeria.
¹⁶ Department of Earth and Environmental Science, Botswana International University of Science and Technology, Private Bag 16, Palapye, Botswana.

Abstract

This study aims to investigate soil organic carbon (SOC) and total nitrogen (TN) contents and stocks, CO₂ emissions and selected soil properties in croplands, grazing lands, exclosures and forest lands of semi-arid Ethiopia. Sampling was done at 0-30, 30-60 and 60-90 cm soil depths and concentration and stocks of SOC, TN and selected soil properties were determined using standard routine laboratory procedures. There were variations in distribution of SOC and TN stock over 90 cm depth across land use types and locations, decreasing from topsoils to subsoil, with average values ranging from 48.68 Mg C ha^-1 and 4.80 Mg N ha^-1 in Hugumburda cropland to 303.53 Mg C ha^-1 and 24.99 Mg N ha^-1 in Desa'a forest respectively. Forest sequestered significant higher SOC and TN stock, decreasing with depth, compared with other land use types. In Desa'a and Hugumburda, the conversion of forest to cropland resulted in a total loss of SOC stock of 9.04 Mg C ha^-1 and 2.05 Mg C ha^-1, respectively, and an increase in CO₂ emission of 33.16 Mg C ha^-1 and 7.52 Mg C ha^-1 yr^-1, respectively. The establishment of 10 years (Geregera) and 6 years (Haikihelet) exclosures on degraded grazing land increased SOC stock by 13% and 37% respectively.

Abstract

Grants and funding