Articles | Volume 10, issue 1
https://doi.org/10.5194/soil-10-151-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/soil-10-151-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Original research article
| 
20 Feb 2024
Original research article |
| 20 Feb 2024
| 20 Feb 2024
Mulch application as the overarching factor explaining increase in soil organic carbon stocks under conservation agriculture in two 8-year-old experiments in Zimbabwe
Armwell Shumba
CORRESPONDING AUTHOR
Department of Plant Production Sciences and Technologies, University of Zimbabwe, Harare, Zimbabwe
CIRAD, UPR AIDA, Harare, Zimbabwe
Fertilizer, Farm Feeds and Remedies Institute, Department of Research and Specialist Services, Ministry of Lands, Agriculture, Fisheries, Water and Rural Development, Harare, Zimbabwe
Regis Chikowo
Department of Plant Production Sciences and Technologies, University of Zimbabwe, Harare, Zimbabwe
International Maize and Wheat Improvement Center (CIMMYT), Mount Pleasant, Harare, Zimbabwe
Christian Thierfelder
International Maize and Wheat Improvement Center (CIMMYT), Mount Pleasant, Harare, Zimbabwe
Marc Corbeels
AIDA, Univ Montpellier, CIRAD, Montpellier, France
International Institute of Tropical Agriculture (IITA), Nairobi, Kenya
Johan Six
Department of Environmental Systems Science, ETH Zurich, 8092 Zurich, Switzerland
Rémi Cardinael
Department of Plant Production Sciences and Technologies, University of Zimbabwe, Harare, Zimbabwe
CIRAD, UPR AIDA, Harare, Zimbabwe
AIDA, Univ Montpellier, CIRAD, Montpellier, France
Related authors
No articles found.
Jize Jiang, Lenny H. E. Winkel, Chloé Wüst-Galley, Daniel Bretscher, Magdalena Necpalova, Andrea Stenke, and Johan Six
Biogeosciences, 23, 6741–6761, https://doi.org/10.5194/bg-23-6741-2026, https://doi.org/10.5194/bg-23-6741-2026, 2026
Short summary
Short summary
We studied nitrogen use in Swiss agriculture for four decades using detailed data and modelling. We found that nitrogen use efficiency improved, while nitrogen losses decreased. Yet, modelling results suggested that cropland soils may lose nitrogen. The results show that policies implementation benefited productivity and reduced pollution. On the other hand, soil nitrogen balance should also be monitored, underscoring the need for integrated nitrogen management.
Marijn Van de Broek and Johan Six
Geosci. Model Dev., 19, 8651–8672, https://doi.org/10.5194/gmd-19-8651-2026, https://doi.org/10.5194/gmd-19-8651-2026, 2026
Short summary
Short summary
Soil organic matter models are characterised by equifinality, the phenomenon whereby multiple parameter sets yield similar results. This study shows that the number of identifiable parameters that can be optimised together is limited, even under data-rich conditions. As a result, overparameterised models show a large variability when simulating future changes. Optimising only identifiable model parameters is therefore necessary to avoid this hidden uncertainty in soil organic matter models.
Jize Jiang, Lenny H. E. Winkel, Andrea Stenke, Magdalena Necpalova, Moritz Laub, Iris Feigenwinter, Nina Buchmann, and Johan Six
EGUsphere, https://doi.org/10.5194/egusphere-2026-4445, https://doi.org/10.5194/egusphere-2026-4445, 2026
Short summary
Short summary
We studied how fertiliser management and a warming climate affect nitrous oxide emissions from agricultural soils in Switzerland over the past fourty years. Using computer simulations and nationwide data, we found that lower fertiliser use reduced emissions, but rising temperatures cancelled part of these mitigations. The results show a trade-off between mitigation actions and environmental-driven feedback, highlighting future efforts must also account for the effects of a changing climate.
Laura Summerauer, Fernando Bamba, Bendicto Akoraebirungi, Ahurra Wobusobozi, Marijn Bauters, Travis William Drake, Negar Haghipour, Clovis Kabaseke, Daniel Muhindo, Landry Cizungu Ntaboba, Leonardo Ramirez-Lopez, Johan Six, Daniel Wasner, and Sebastian Doetterl
Biogeosciences, 23, 3907–3938, https://doi.org/10.5194/bg-23-3907-2026, https://doi.org/10.5194/bg-23-3907-2026, 2026
Short summary
Short summary
Deforestation for croplands on tropical hillslopes causes severe soil degradation and loss of fertile topsoil. We found that this leads to a steep decline in soil fertility, including organic carbon, nitrogen, and phosphorus. This makes the land unproductive, often leading farmers to abandon it. Replanting with Eucalyptus trees doesn't restore fertility. This degradation leads to cropland lifespans of only 145±56 years and poses a serious threat to future food production.
Mosisa Tujuba Wakjira, Renske Hijbeek, Joost van Heerwaarden, John Koestel, Sara Bonetti, Johan Six, and Katrien Descheemaeker
EGUsphere, https://doi.org/10.5194/egusphere-2026-2816, https://doi.org/10.5194/egusphere-2026-2816, 2026
Short summary
Short summary
Nowadays, minimizing agricultural soil tillage is widely promoted but often leads to lower crop yields. This study combines experimental evidence globally to identify soil-related causes of these yield declines. Results show that minimized tillage, especially without leaving crop residues on the field, can cause soil compaction, limiting root growth and the movement of air and water needed by crops. This suggests that conservation agriculture should only be applied where suitable.
Eric Rahn, Mirjam Pulleman, Gabriel Y. K. Moinet, Rémi Cardinael, Dick Brus, Stefan Hauser, Johan Six, José Francisco Valle Pilia, Estephania Nieto, and Isabela Otero
EGUsphere, https://doi.org/10.5194/egusphere-2026-1479, https://doi.org/10.5194/egusphere-2026-1479, 2026
This preprint is open for discussion and under review for SOIL (SOIL).
Short summary
Short summary
To improve understanding of how coffee farming affects soil carbon storage, we reviewed 80 studies and found large differences in methods and reporting. Based on this evidence, we propose clear guidance for future research, including better study design, deeper soil sampling, careful measurement of soil density, and transparent reporting. Stronger and more consistent methods are needed so that research can produce reliable evidence to guide climate policy and sustainable coffee management.
Marijn Van de Broek, Fiona Stewart-Smith, Moritz Laub, Marc Corbeels, Monicah Wanjiku Mucheru-Muna, Daniel Mugendi, Wycliffe Waswa, Bernard Vanlauwe, and Johan Six
SOIL, 12, 187–204, https://doi.org/10.5194/soil-12-187-2026, https://doi.org/10.5194/soil-12-187-2026, 2026
Short summary
Short summary
To improve soil health and increase crop yields, organic matter is commenly added to arable soils. Studying the effect of different organic resources on soil organic carbon sequestration in four long-term field trials in Kenya, we found that only a small portion (< 7 %) of added organic carbon was stabilised, which was only observed in the top 15 cm of the soil. These results underline the challenges associated with increasing the organic carbon content of tropical arable soils.
Nathan Carlier, Matti Barthel, Antoine de Clippele, Lissie Willemijn de Groot, Travis William Drake, Jordon Dennis Hemingway, Yi Hou, José Nlandu Wabakanghanzi, Joseph Zambo Mandea, Pengzhi Zhao, Johan Six, and Kristof Van Oost
EGUsphere, https://doi.org/10.5194/egusphere-2026-247, https://doi.org/10.5194/egusphere-2026-247, 2026
Short summary
Short summary
The Congo River Basin, a region of global significance, is undergoing a strong increase in population, which will in turn increase soil erosion, impacting soil fertility and the carbon cycle. We examined river sediment (eroded soil) transport, whereby we provided information on the main contributors of sediment to the Congo River. We also highlighted the role of a swampy region which removes large amounts of sediment from the water, acting as a regulator sediment transport to the Congo River.
Antoine de Clippele, Astrid C. H. Jaeger, Simon Baumgartner, Marijn Bauters, Pascal Boeckx, Clement Botefa, Glenn Bush, Jessica Carilli, Travis W. Drake, Christian Ekamba, Gode Lompoko, Nivens Bey Mukwiele, Kristof Van Oost, Roland A. Werner, Joseph Zambo, Johan Six, and Matti Barthel
Biogeosciences, 22, 3011–3027, https://doi.org/10.5194/bg-22-3011-2025, https://doi.org/10.5194/bg-22-3011-2025, 2025
Short summary
Short summary
Tropical forest soils as a large terrestrial source of carbon dioxide (CO2) contribute to the global greenhouse gas budget. Despite this, carbon flux data from forested wetlands are scarce in tropical Africa. The study presents 3 years of semi-continuous measurements of surface CO2 fluxes within the Congo Basin. Although no seasonal patterns were evident, our results show a positive effect of soil temperature and moisture, while a quadratic relationship was observed with the water table.
Claude Raoul Müller, Johan Six, Daniel Mugendi Njiru, Bernard Vanlauwe, and Marijn Van de Broek
Biogeosciences, 22, 2733–2747, https://doi.org/10.5194/bg-22-2733-2025, https://doi.org/10.5194/bg-22-2733-2025, 2025
Short summary
Short summary
We studied how different organic and inorganic nutrient inputs affect soil organic carbon (SOC) down to 70 cm in Kenya. After 19 years, all organic treatments increased SOC stocks compared with the control, but mineral nitrogen had no significant effect. Manure was the organic treatment that significantly increased SOC at the deepest soil depths, as its effect could be observed down to 60 cm. Manure was the best strategy to limit SOC loss in croplands and maintain soil quality after deforestation.
Roxanne Daelman, Marijn Bauters, Matti Barthel, Emmanuel Bulonza, Lodewijk Lefevre, José Mbifo, Johan Six, Klaus Butterbach-Bahl, Benjamin Wolf, Ralf Kiese, and Pascal Boeckx
Biogeosciences, 22, 1529–1542, https://doi.org/10.5194/bg-22-1529-2025, https://doi.org/10.5194/bg-22-1529-2025, 2025
Short summary
Short summary
The increase in atmospheric concentrations of several greenhouse gases (GHGs) since 1750 is attributed to human activity. However, natural ecosystems, such as tropical forests, also contribute to GHG budgets. The Congo Basin hosts the second largest tropical forest and is understudied. In this study, measurements of soil GHG exchange were carried out during 16 months in a tropical forest in the Congo Basin. Overall, the soil acted as a major source of CO2 and N2O and a minor sink of CH4.
Marijn Van de Broek, Gerard Govers, Marion Schrumpf, and Johan Six
Biogeosciences, 22, 1427–1446, https://doi.org/10.5194/bg-22-1427-2025, https://doi.org/10.5194/bg-22-1427-2025, 2025
Short summary
Short summary
Soil organic carbon models are used to predict how soils affect the concentration of CO2 in the atmosphere. We show that equifinality – the phenomenon that different parameter values lead to correct overall model outputs, albeit with a different model behaviour – is an important source of model uncertainty. Our results imply that adding more complexity to soil organic carbon models is unlikely to lead to better predictions as long as more data to constrain model parameters are not available.
Mosisa Tujuba Wakjira, Nadav Peleg, Johan Six, and Peter Molnar
Hydrol. Earth Syst. Sci., 29, 863–886, https://doi.org/10.5194/hess-29-863-2025, https://doi.org/10.5194/hess-29-863-2025, 2025
Short summary
Short summary
In this study, we implement a climate, water, and crop interaction model to evaluate current conditions and project future changes in rainwater availability and its yield potential, with the goal of informing adaptation policies and strategies in Ethiopia. Although climate change is likely to increase rainfall in Ethiopia, our findings suggest that water-scarce croplands in Ethiopia are expected to face reduced crop yields during the main growing season due to increases in temperature.
Vira Leng, Rémi Cardinael, Florent Tivet, Vang Seng, Phearum Mark, Pascal Lienhard, Titouan Filloux, Johan Six, Lyda Hok, Stéphane Boulakia, Clever Briedis, João Carlos de Moraes Sá, and Laurent Thuriès
SOIL, 10, 699–725, https://doi.org/10.5194/soil-10-699-2024, https://doi.org/10.5194/soil-10-699-2024, 2024
Short summary
Short summary
We assessed the long-term impacts of no-till cropping systems on soil organic carbon and nitrogen dynamics down to 1 m depth under the annual upland crop productions (cassava, maize, and soybean) in the tropical climate of Cambodia. We showed that no-till systems combined with rotations and cover crops could store large amounts of carbon in the top and subsoil in both the mineral organic matter and particulate organic matter fractions. We also question nitrogen management in these systems.
Moritz Laub, Magdalena Necpalova, Marijn Van de Broek, Marc Corbeels, Samuel Mathu Ndungu, Monicah Wanjiku Mucheru-Muna, Daniel Mugendi, Rebecca Yegon, Wycliffe Waswa, Bernard Vanlauwe, and Johan Six
Biogeosciences, 21, 3691–3716, https://doi.org/10.5194/bg-21-3691-2024, https://doi.org/10.5194/bg-21-3691-2024, 2024
Short summary
Short summary
We used the DayCent model to assess the potential impact of integrated soil fertility management (ISFM) on maize production, soil fertility, and greenhouse gas emission in Kenya. After adjustments, DayCent represented measured mean yields and soil carbon stock changes well and N2O emissions acceptably. Our results showed that soil fertility losses could be reduced but not completely eliminated with ISFM and that, while N2O emissions increased with ISFM, emissions per kilogram yield decreased.
Claude Raoul Müller, Johan Six, Liesa Brosens, Philipp Baumann, Jean Paolo Gomes Minella, Gerard Govers, and Marijn Van de Broek
SOIL, 10, 349–365, https://doi.org/10.5194/soil-10-349-2024, https://doi.org/10.5194/soil-10-349-2024, 2024
Short summary
Short summary
Subsoils in the tropics are not as extensively studied as those in temperate regions. In this study, the conversion of forest to agriculture in a subtropical region affected the concentration of stabilized organic carbon (OC) down to 90 cm depth, while no significant differences between 90 cm and 300 cm were detected. Our results suggest that subsoils below 90 cm are unlikely to accumulate additional stabilized OC through reforestation over decadal periods due to declining OC input with depth.
Johan Six, Sebastian Doetterl, Moritz Laub, Claude R. Müller, and Marijn Van de Broek
SOIL, 10, 275–279, https://doi.org/10.5194/soil-10-275-2024, https://doi.org/10.5194/soil-10-275-2024, 2024
Short summary
Short summary
Soil C saturation has been tested in several recent studies and led to a debate about its existence. We argue that, to test C saturation, one should pay attention to six fundamental principles: the right measures, the right units, the right dispersive energy and application, the right soil type, the right clay type, and the right saturation level. Once we take care of those six rights across studies, we find support for a maximum of C stabilized by minerals and thus soil C saturation.
Moritz Laub, Sergey Blagodatsky, Marijn Van de Broek, Samuel Schlichenmaier, Benjapon Kunlanit, Johan Six, Patma Vityakon, and Georg Cadisch
Geosci. Model Dev., 17, 931–956, https://doi.org/10.5194/gmd-17-931-2024, https://doi.org/10.5194/gmd-17-931-2024, 2024
Short summary
Short summary
To manage soil organic matter (SOM) sustainably, we need a better understanding of the role that soil microbes play in aggregate protection. Here, we propose the SAMM model, which connects soil aggregate formation to microbial growth. We tested it against data from a tropical long-term experiment and show that SAMM effectively represents the microbial growth, SOM, and aggregate dynamics and that it can be used to explore the importance of aggregate formation in SOM stabilization.
Moritz Laub, Marc Corbeels, Antoine Couëdel, Samuel Mathu Ndungu, Monicah Wanjiku Mucheru-Muna, Daniel Mugendi, Magdalena Necpalova, Wycliffe Waswa, Marijn Van de Broek, Bernard Vanlauwe, and Johan Six
SOIL, 9, 301–323, https://doi.org/10.5194/soil-9-301-2023, https://doi.org/10.5194/soil-9-301-2023, 2023
Short summary
Short summary
In sub-Saharan Africa, long-term low-input maize cropping threatens soil fertility. We studied how different quality organic inputs combined with mineral N fertilizer could counteract this. Farmyard manure was the best input to counteract soil carbon loss; mineral N fertilizer had no effect on carbon. Yet, the rates needed to offset soil carbon losses are unrealistic for farmers (>10 t of dry matter per hectare and year). Additional agronomic measures may be needed.
Kristof Van Oost and Johan Six
Biogeosciences, 20, 635–646, https://doi.org/10.5194/bg-20-635-2023, https://doi.org/10.5194/bg-20-635-2023, 2023
Short summary
Short summary
The direction and magnitude of the net erosion-induced land–atmosphere C exchange have been the topic of a big scientific debate for more than a decade now. Many have assumed that erosion leads to a loss of soil carbon to the atmosphere, whereas others have shown that erosion ultimately leads to a carbon sink. Here, we show that the soil carbon erosion source–sink paradox is reconciled when the broad range of temporal and spatial scales at which the underlying processes operate are considered.
Kenji Fujisaki, Tiphaine Chevallier, Antonio Bispo, Jean-Baptiste Laurent, François Thevenin, Lydie Chapuis-Lardy, Rémi Cardinael, Christine Le Bas, Vincent Freycon, Fabrice Bénédet, Vincent Blanfort, Michel Brossard, Marie Tella, and Julien Demenois
SOIL, 9, 89–100, https://doi.org/10.5194/soil-9-89-2023, https://doi.org/10.5194/soil-9-89-2023, 2023
Short summary
Short summary
This paper presents a first comprehensive thesaurus for management practices driving soil organic carbon (SOC) storage. So far, a comprehensive thesaurus of management practices in agriculture and forestry has been lacking. It will help to merge datasets, a promising way to evaluate the impacts of management practices in agriculture and forestry on SOC. Identifying the drivers of SOC stock changes is of utmost importance to contribute to global challenges (climate change, food security).
Charlotte Decock, Juhwan Lee, Matti Barthel, Elizabeth Verhoeven, Franz Conen, and Johan Six
Biogeosciences Discuss., https://doi.org/10.5194/bg-2022-221, https://doi.org/10.5194/bg-2022-221, 2022
Preprint withdrawn
Short summary
Short summary
One of the least well understood processes in the nitrogen (N) cycle is the loss of nitrogen gas (N2), referred to as total denitrification. This is mainly due to the difficulty of quantifying total denitrification in situ. In this study, we developed and tested a novel modeling approach to estimate total denitrification over the depth profile, based on concentrations and isotope values of N2O. Our method will help close N budgets and identify management strategies that reduce N pollution.
Tegawende Léa Jeanne Ilboudo, Lucien NGuessan Diby, Delwendé Innocent Kiba, Tor Gunnar Vågen, Leigh Ann Winowiecki, Hassan Bismarck Nacro, Johan Six, and Emmanuel Frossard
EGUsphere, https://doi.org/10.5194/egusphere-2022-209, https://doi.org/10.5194/egusphere-2022-209, 2022
Preprint withdrawn
Short summary
Short summary
Our results showed that at landscape level SOC stock variability was mainly explained by clay content. We found significant linear positive relationships between VC and SOC stocks for the land uses annual croplands, perennial croplands, grasslands and bushlands without soil depth restrictions until 110 cm. We concluded that in the forest-savanna transition zone, soil properties and topography determine land use, which in turn affects the stocks of SOC and TN and to some extent the VC stocks.
Philipp Baumann, Juhwan Lee, Emmanuel Frossard, Laurie Paule Schönholzer, Lucien Diby, Valérie Kouamé Hgaza, Delwende Innocent Kiba, Andrew Sila, Keith Sheperd, and Johan Six
SOIL, 7, 717–731, https://doi.org/10.5194/soil-7-717-2021, https://doi.org/10.5194/soil-7-717-2021, 2021
Short summary
Short summary
This work delivers openly accessible and validated calibrations for diagnosing 26 soil properties based on mid-infrared spectroscopy. These were developed for four regions in Burkina Faso and Côte d'Ivoire, including 80 fields of smallholder farmers. The models can help to site-specifically and cost-efficiently monitor soil quality and fertility constraints to ameliorate soils and yields of yam or other staple crops in the four regions between the humid forest and the northern Guinean savanna.
Laura Summerauer, Philipp Baumann, Leonardo Ramirez-Lopez, Matti Barthel, Marijn Bauters, Benjamin Bukombe, Mario Reichenbach, Pascal Boeckx, Elizabeth Kearsley, Kristof Van Oost, Bernard Vanlauwe, Dieudonné Chiragaga, Aimé Bisimwa Heri-Kazi, Pieter Moonen, Andrew Sila, Keith Shepherd, Basile Bazirake Mujinya, Eric Van Ranst, Geert Baert, Sebastian Doetterl, and Johan Six
SOIL, 7, 693–715, https://doi.org/10.5194/soil-7-693-2021, https://doi.org/10.5194/soil-7-693-2021, 2021
Short summary
Short summary
We present a soil mid-infrared library with over 1800 samples from central Africa in order to facilitate soil analyses of this highly understudied yet critical area. Together with an existing continental library, we demonstrate a regional analysis and geographical extrapolation to predict total carbon and nitrogen. Our results show accurate predictions and highlight the value that the data contribute to existing libraries. Our library is openly available for public use and for expansion.
Cited articles
Amos, B. and Walters, D. T.: Maize Root Biomass and Net Rhizodeposited Carbon, Soil Sci. Soc. Am. J., 70, 1489–1503, https://doi.org/10.2136/sssaj2005.0216, 2006.
Angers, D. A. and Eriksen-Hamel, N. S.: Full-inversion tillage and organic carbon distribution in soil profiles: A meta-analysis, Soil Sci. Soc. Am. J., 72, 1370–1374, https://doi.org/10.2136/sssaj2007.0342, 2008.
Angers, D. A., Bolinder, M. A., Carter, M. R., Gregorich, E. G., Drury, C. F., Liang, B. C., Voroney, R. P., Simard, R. R., Donald, R. G., Bevaert, R. P., and Martel, J.: Impact of tillage practices on organic carbon and nitrogen storage in cool, humid soils of eastern Canada, Soil Till. Res., 41, 191–201, https://doi.org/10.4141/S96-111, 1997.
Bai, X., Huang, Y., Ren, W., Coyne, M., Jacinthe, P.-A., Bo, T., Hui, D., Yang, J., and Matocha, C.: Responses of soil carbon sequestration to climate-smart agriculture practices: A meta-analysis, Glob. Change Biol., 25, 2591–2606, https://doi.org/10.1111/gcb.14658, 2019.
Balesdent, J., Derrien, D., Fontaine, S., Kirman, S., Klumpp, K., Loiseau, P., Marol, C., Nguyen, C., Pean, M., Personeni, E., and Robin, C.: Contribution de la rhizodéposition aux matières organiques du sol, quelques implications pour la modélisation de la dynamique du carbone, Etude Gest. des sols, 18, 201–216, 2011.
Balesdent, J., Basile-Doelsch, I., Chadoeuf, J., Cornu, S., Derrien, D., Fekiacova, Z., and Hatté, C.: Atmosphere–soil carbon transfer as a function of soil depth, Nature, 559, 599–602, https://doi.org/10.1038/s41586-018-0328-3, 2018.
Bationo, A., Kihara, J., Vanlauwe, B., Waswa, B., Adolwa, I., and Saidou, K. (Eds.): Overview of Long Term Experiments in Africa, in: Lessons Learned from Long-Term Soil Fertility Management Experiments in Africa, Springer Science+Business Media, Dordrecht, 1–26, https://doi.org/10.1007/978-94-007-2938-4, 2013.
Baudron, F., Andersson, J. A., Corbeels, M., and Giller, K. E.: Failing to Yield? Ploughs, Conservation Agriculture and the Problem of Agricultural Intensification: An Example from the Zambezi Valley, Zimbabwe, J. Dev. Stud., 48, 393–412, https://doi.org/10.1080/00220388.2011.587509, 2012.
Bohoussou, Y. N. D., Kou, Y. H., Yu, W. B., Lin, B. J., Virk, A. L., Zhao, X., Dang, Y. P., and Zhang, H. L.: Impacts of the components of conservation agriculture on soil organic carbon and total nitrogen storage: A global meta-analysis, Sci. Total Environ., 842, 156822, https://doi.org/10.1016/J.SCITOTENV.2022.156822, 2022.
Bolker, B. M., Brooks, M. E., Clark, C. J., Geange, S. W., Poulsen, J. R., Stevens, M. H. H., and White, J. S. S.: Generalized linear mixed models: a practical guide for ecology and evolution, Trends Ecol. Evol., 24, 127–135, https://doi.org/10.1016/j.tree.2008.10.008, 2009.
Bossio, D. A., Cook-Patton, S. C., Ellis, P. W., Fargione, J., Sanderman, J., Smith, P., Wood, S., Zomer, R. J., von Unger, M., Emmer, I. M., and Griscom, B. W.: The role of soil carbon in natural climate solutions, Nat. Sustain., 3, 391–398, https://doi.org/10.1038/s41893-020-0491-z, 2020.
Button, E. S., Pett-Ridge, J., Murphy, D. V., Kuzyakov, Y., Chadwick, D. R., and Jones, D. L.: Deep-C storage: Biological, chemical and physical strategies to enhance carbon stocks in agricultural subsoils, Soil Biol. Biochem., 170, 108697, https://doi.org/10.1016/j.soilbio.2022.108697, 2022.
Cai, A., Han, T., Ren, T., Sanderman, J., Rui, Y., Wang, B., Smith, P., Xu, M., and Li, Y.: Declines in soil carbon storage under no tillage can be alleviated in the long run, Geoderma, 425, 1–3, https://doi.org/10.1016/j.geoderma.2022.116028, 2022.
Cambardella, C. A. and Elliott, E. T.: Carbon and Nitrogen Distribution in Aggregates from Cultivated and Native Grassland Soils, Soil Sci. Soc. Am. J., 57, 1071–1076, https://doi.org/10.2136/SSSAJ1993.03615995005700040032X, 1993.
Cardinael, R., Chevallier, T., Barthès, B. G., Saby, N. P. A., Parent, T., Dupraz, C., Bernoux, M., and Chenu, C.: Impact of alley cropping agroforestry on stocks, forms and spatial distribution of soil organic carbon – A case study in a Mediterranean context, Geoderma, 259–260, 288–299, https://doi.org/10.1016/j.geoderma.2015.06.015, 2015.
Cardinael, R., Guibert, H., Kouassi Brédoumy, S. T., Gigou, J., N'Goran, K. E., and Corbeels, M.: Sustaining maize yields and soil carbon following land clearing in the forest–savannah transition zone of West Africa: Results from a 20 year experiment, Field Crop. Res., 275, 108335, https://doi.org/10.1016/j.fcr.2021.108335, 2022.
Cheesman, S., Thierfelder, C., Eash, N. S., Kassie, G. T., and Frossard, E.: Soil carbon stocks in conservation agriculture systems of Southern Africa, Soil Till. Res., 156, 99–109, https://doi.org/10.1016/j.still.2015.09.018, 2016.
Chen, R., Senbayram, M., Blagodatsky, S., Myachina, O., Dittert, K., Lin, X., Blagodatskaya, E., and Kuzyakov, Y.: Soil C and N availability determine the priming effect: Microbial N mining and stoichiometric decomposition theories, Global Change Biol., 20, 2356–2367, https://doi.org/10.1111/gcb.12475, 2014.
Chikowo, R., Mapfumo, P., Nyamugafata, P., Nyamadzawo, G., and Giller, K. E.: Nitrate-N dynamics following improved fallows and maize root development in a Zimbabwean sandy clay loam, Agroforest. Syst., 59, 187–195, https://doi.org/10.1023/B:AGFO.0000005219.07409.a0, 2003.
Chivenge, P. P., Murwira, H. K., Giller, K. E., Mapfumo, P., and Six, J.: Long-term impact of reduced tillage and residue management on soil carbon stabilization: Implications for conservation agriculture on contrasting soils, Soil Till. Res., 94, 328–337, https://doi.org/10.1016/j.still.2006.08.006, 2007.
Christensen, B. T.: Decomposability of organic matter in particle size fractions from field soils with straw incorporation, Soil Biol. Biochem., 19, 429–435, https://doi.org/10.1016/0038-0717(87)90034-4, 1987.
Churchman, G. J., Singh, M., Schapel, A., Sarkar, B., and Bolan, N.: Clay Minerals As the Key To the Sequestration of Carbon in Soils, Clay. Clay Miner., 68, 135–143, https://doi.org/10.1007/s42860-020-00071-z, 2020.
Corbeels, M., Cardinael, R., Powlson, D., Chikowo, R., and Gerard, B.: Carbon sequestration potential through conservation agriculture in Africa has been largely overestimated: Comment on: “Meta-analysis on carbon sequestration through conservation agriculture in Africa,” Soil Till. Res., 196, 104300, https://doi.org/10.1016/j.still.2019.104300, 2020a.
Corbeels, M., Naudin, K., Whitbread, A. M., Kühne, R., and Letourmy, P.: Limits of conservation agriculture to overcome low crop yields in sub-Saharan Africa, Nat. Food, 1, 447–454, https://doi.org/10.1038/s43016-020-0114-x, 2020b.
Cotrufo, M. F., Wallenstein, M. D., Boot, C. M., Denef, K., and Paul, E.: The Microbial Efficiency-Matrix Stabilization (MEMS) framework integrates plant litter decomposition with soil organic matter stabilization: Do labile plant inputs form stable soil organic matter?, Global Change Biol., 19, 988–995, https://doi.org/10.1111/gcb.12113, 2013.
Dignac, M. F., Derrien, D., Barré, P., Barot, S., Cécillon, L., Chenu, C., Chevallier, T., Freschet, G. T., Garnier, P., Guenet, B., Hedde, M., Klumpp, K., Lashermes, G., Maron, P. A., Nunan, N., Roumet, C., and Basile-Doelsch, I.: Increasing soil carbon storage: mechanisms, effects of agricultural practices and proxies. A review, Agron. Sustain. Dev., 37, 14, https://doi.org/10.1007/s13593-017-0421-2, 2017.
Dolan, M. S., Clapp, C. E., Allmaras, R. R., Baker, J. M., and Molina, J. A. E.: Soil organic carbon and nitrogen in a Minnesota soil as related to tillage, residue and nitrogen management, Soil Till. Res., 89, 221–231, https://doi.org/10.1016/j.still.2005.07.015, 2006.
Doran, J. W., Elliott, E. T., and Paustian, K.: Soil microbial activity, nitrogen cycling, and long-term changes in organic carbon pools as related to fallow tillage management, Soil Till. Res., 49, 3–18, https://doi.org/10.1016/S0167-1987(98)00150-0, 1998.
Du, Z., Angers, D. A., Ren, T., Zhang, Q., and Li, G.: The effect of no-till on organic C storage in Chinese soils should not be overemphasized: A meta-analysis, Agr. Ecosyst. Environ., 236, 1–11, https://doi.org/10.1016/j.agee.2016.11.007, 2017.
Dube, E., Chiduza, C., and Muchaonyerwa, P.: Conservation agriculture effects on soil organic matter on a Haplic Cambisol after four years of maize-oat and maize-grazing vetch rotations in South Africa, Soil Till. Res., 123, 21–28, https://doi.org/10.1016/j.still.2012.02.008, 2012.
Dunjana, N., Nyamugafata, P., Shumba, A., Nyamangara, J., and Zingore, S.: Effects of cattle manure on selected soil physical properties of smallholder farms on two soils of Murewa, Zimbabwe, Soil Use Manage., 28, 221–228, https://doi.org/10.1111/j.1475-2743.2012.00394.x, 2012.
Ellert, B. H. and Bettany, J. R.: Calculation of organic matter and nutrients stored in soils under contrasting management regimes, Can. J. Soil Sci., 75, 529–538, https://doi.org/10.4141/cjss95-075, 1995.
Feller, C. and Beare, M. H.: Physical control of soil organic matter dynamics in the tropics, Geoderma, 79, 69–116, https://doi.org/10.1016/S0016-7061(97)00039-6, 1997.
Giller, K. E., Witter, E., Corbeels, M., and Tittonell, P.: Conservation agriculture and smallholder farming in Africa: The heretics' view, Field Crop. Res., 114, 23–34, https://doi.org/10.1016/j.fcr.2009.06.017, 2009.
Giller, K. E., Andersson, J. A., Corbeels, M., Kirkegaard, J., Mortensen, D., Erenstein, O., and Vanlauwe, B.: Beyond conservation agriculture, Front. Plant Sci., 6, 1–14, https://doi.org/10.3389/fpls.2015.00870, 2015.
Han, L., Sun, K., Jin, J., and Xing, B.: Some concepts of soil organic carbon characteristics and mineral interaction from a review of literature, Soil Biol. Biochem., 94, 107–121, https://doi.org/10.1016/j.soilbio.2015.11.023, 2016.
Harrison, R. B., Footen, P. W., Harrison, R. B., Footen, P. W., and Strahm, B. D.: Deep Soil Horizons: Contribution and Importance to Soil Carbon Pools and in Assessing Whole-Ecosystem Response to Management and Global Change, For. Sci., 57, 67–76, 2011.
Hirte, J., Leifeld, J., Abiven, S., Oberholzer, H. R., and Mayer, J.: Below ground carbon inputs to soil via root biomass and rhizodeposition of field-grown maize and wheat at harvest are independent of net primary productivity, Agr. Ecosyst. Environ., 265, 556–566, https://doi.org/10.1016/j.agee.2018.07.010, 2018.
Hirte, J., Walder, F., Hess, J., Büchi, L., Colombi, T., van der Heijden, M. G., and Mayer, J.: Enhanced root carbon allocation through organic farming is restricted to topsoils, Sci. Total Environ., 755, 143551, https://doi.org/10.1016/j.scitotenv.2020.143551, 2021.
IPCC: 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, edited by: Calvo Buendia, E., Tanabe, K., Kranjc, A., Baasansuren, J., Fukuda, M., Ngarize, S., Osako, A., Pyrozhenko, Y., Shermanau, P. and Federici, S., IPCC, Switzerland, ISBN 978-4-88788-232-4, 2019.
Jephita, G., Jefline, K., Willis, G., and Justice, N.: Carbon stock, aggregate stability and hydraulic properties of soils under tillage, crop rotation and mineral fertiliser application in sub-humid Zimbabwe, Heliyon, 9, Heliyon, e15846, https://doi.org/10.1016/j.heliyon.2023.e15846, 2023.
Jones, D. L., Nguyen, C., and Finlay, R. D.: Carbon flow in the rhizosphere: carbon trading at the soil – root interface, Plant Soil, 321, 5–33, https://doi.org/10.1007/s11104-009-9925-0, 2009.
Kahn, B. A. and Schroeder, J. L.: Root Characteristics and Seed Yields of Cowpeas Grown with and without Added Nitrogen Fertilizer, HortScience, 34, 1238–1239, https://doi.org/10.21273/hortsci.34.7.1238, 1999.
Kassam, A., Friedrich, T., and Derpsch, R.: Global spread of Conservation Agriculture, Int. J. Environ. Stud., 76, 29–51, https://doi.org/10.1080/00207233.2018.1494927, 2019.
Kell, D. B.: Breeding crop plants with deep roots: their role in sustainable carbon, nutrient and water sequestration, Ann. Bot.-London, 108, 407–418, https://doi.org/10.1093/aob/mcr175, 2011.
Kimaro, A. A., Mpanda, M., Rioux, J., Aynekulu, E., Shaba, S., Thiong'o, M., Mutuo, P., Abwanda, S., Shepherd, K., Neufeldt, H., and Rosenstock, T. S.: Is conservation agriculture “climate-smart” for maize farmers in the highlands of Tanzania?, Nutr. Cycl. Agroecosys., 105, 217–228, https://doi.org/10.1007/s10705-015-9711-8, 2016.
Kimiti, J. M.: Influence of integrated soil nutrient management on cowpea root growth in the semi-arid Eastern Kenya, Afr. J. Agr. Res., 6, 3084–3091, 2011.
Kodzwa, J. J., Gotosa, J., and Nyamangara, J.: Mulching is the most important of the three conservation agriculture principles in increasing crop yield in the short term, under sub humid tropical conditions in Zimbabwe, Soil Till. Res., 197, 104515, https://doi.org/10.1016/j.still.2019.104515, 2020.
Koga, N. and Tsuji, H.: Effects of reduced tillage, crop residue management and manure application practices on crop yields and soil carbon sequestration on an Andisol in northern Japan, Soil Sci. Plant Nutr., 55, 546–557, https://doi.org/10.1111/j.1747-0765.2009.00385.x, 2009.
Kopittke, P. M., Hernandez-Soriano, M. C., Dalal, R. C., Finn, D., Menzies, N. W., Hoeschen, C., and Mueller, C. W.: Nitrogen-rich microbial products provide new organo-mineral associations for the stabilization of soil organic matter, Global Change Biol., 24, 1762–1770, https://doi.org/10.1111/gcb.14009, 2018.
Kravchenko, A. N. and Guber, A. K.: Soil pores and their contributions to soil carbon processes, Geoderma, 287, 31–39, https://doi.org/10.1016/j.geoderma.2016.06.027, 2017.
Kravchenko, A. N. and Robertson, G. P.: Whole-Profile Soil Carbon Stocks: The Danger of Assuming Too Much from Analyses of Too Little, Soil Sci. Soc. Am. J., 75, 235–240, https://doi.org/10.2136/sssaj2010.0076, 2011.
Lal, R.: Residue management, conservation tillage and soil restoration for mitigating greenhouse effect by CO2-enrichment, Soil Till. Res., 43, 81–107, 1997.
Lal, R.: Sequestering carbon and increasing productivity by conservation agriculture, J. Soil Water Conserv., 70, 55A–62A, https://doi.org/10.2489/jswc.70.3.55A, 2015.
Lal, R.: Digging deeper: A holistic perspective of factors affecting soil organic carbon sequestration in agroecosystems, Glob. Change Biol., 24, 3285–3301, https://doi.org/10.1111/gcb.14054, 2018.
Laub, M., Corbeels, M., Couëdel, A., Ndungu, S. M., Mucheru-Muna, M. W., Mugendi, D., Necpalova, M., Waswa, W., Van de Broek, M., Vanlauwe, B., and Six, J.: Managing soil organic carbon in tropical agroecosystems: evidence from four long-term experiments in Kenya, SOIL, 9, 301–323, https://doi.org/10.5194/soil-9-301-2023, 2023.
Leal, O. A., Amado, T. J. C., Fiorin, J. E., Keller, C., Reimche, G. B., Rice, C. W., Nicoloso, R. S., Bortolotto, R. P., and Schwalbert, R.: Linking cover crop residue quality and tillage system to CO2-C emission, soil C and N stocks and crop yield based on a long-term experiment, Agronomy, 10, 1848, https://doi.org/10.3390/agronomy10121848, 2020.
Li, Y., Li, Z., Chang, S. X., Cui, S., Jagadamma, S., Zhang, Q., and Cai, Y.: Residue retention promotes soil carbon accumulation in minimum tillage systems: Implications for conservation agriculture, Sci. Total Environ., 740, 140147, https://doi.org/10.1016/j.scitotenv.2020.140147, 2020.
Liang, B. C., VandenBygaart, A. J., MacDonald, J. D., Cerkowniak, D., McConkey, B. G., Desjardins, R. L., and Angers, D. A.: Revisiting no-till's impact on soil organic carbon storage in Canada, Soil Till. Res., 198, 104529, https://doi.org/10.1016/j.still.2019.104529, 2020.
Lorenz, K. and Lal, R.: The Depth Distribution of Soil Organic Carbon in Relation to Land Use and Management and the Potential of Carbon Sequestration in Subsoil Horizons, Adv. Agron., 88, 35–66, https://doi.org/10.1016/S0065-2113(05)88002-2, 2005.
Ma, S., He, F., Tian, D., Zou, D., Yan, Z., Yang, Y., Zhou, T., Huang, K., Shen, H., and Fang, J.: Variations and determinants of carbon content in plants: a global synthesis, Biogeosciences, 15, 693–702, https://doi.org/10.5194/bg-15-693-2018, 2018.
Malepfane, N. M., Muchaonyerwa, P., Hughes, J. C., and Zengeni, R.: Land use and site effects on the distribution of carbon in some humic soil profiles of KwaZulu-Natal, South Africa, Heliyon, 8, e08709, https://doi.org/10.1016/j.heliyon.2021.e08709, 2022.
Mapanda, F., Mupini, J., Wuta, M., Nyamangara, J., and Rees, R. M.: A cross-ecosystem assessment of the effects of land cover and land use on soil emission of selected greenhouse gases and related soil properties in Zimbabwe, Eur. J. Soil Sci., 61, 721–733, https://doi.org/10.1111/j.1365-2389.2010.01266.x, 2010.
Mbanyele, V., Mtambanengwe, F., Nezomba, H., Groot, J. C. J., and Mapfumo, P.: Comparative short-term performance of soil water management options for increased productivity of maize-cowpea intercropping in semi-arid Zimbabwe, J. Agric. Food Res., 5, 100189, https://doi.org/10.1016/j.jafr.2021.100189, 2021.
Mhlanga, B., Ercoli, L., Pellegrino, E., Onofri, A., and Thierfelder, C.: The crucial role of mulch to enhance the stability and resilience of cropping systems in southern Africa, Agron. Sustain. Dev., 41, 29, https://doi.org/10.1007/s13593-021-00687-y, 2021.
Mhlanga, B., Ercoli, L., Thierfelder, C., and Pellegrino, E.: Conservation agriculture practices lead to diverse weed communities and higher maize grain yield in Southern Africa, Field Crop. Res., 289, 108724, https://doi.org/10.1016/j.fcr.2022.108724, 2022a.
Mhlanga, B., Pellegrino, E., Thierfelder, C., and Ercoli, L.: Conservation agriculture practices drive maize yield by regulating soil nutrient availability, arbuscular mycorrhizas, and plant nutrient uptake, Field Crop. Res., 277, 108403, https://doi.org/10.1016/j.fcr.2021.108403, 2022b.
Minasny, B., Malone, B. P., McBratney, A. B., Angers, D. A., Arrouays, D., Chambers, A., Chaplot, V., Chen, Z. S., Cheng, K., Das, B. S., Field, D. J., Gimona, A., Hedley, C. B., Hong, S. Y., Mandal, B., Marchant, B. P., Martin, M., McConkey, B. G., Mulder, V. L., O'Rourke, S., Richer-de-Forges, A. C., Odeh, I., Padarian, J., Paustian, K., Pan, G., Poggio, L., Savin, I., Stolbovoy, V., Stockmann, U., Sulaeman, Y., Tsui, C. C., Vågen, T. G., van Wesemael, B., and Winowiecki, L.: Soil carbon 4 per mille, Geoderma, 292, 59–86, https://doi.org/10.1016/j.geoderma.2017.01.002, 2017.
Mtambanengwe, F., Mapfumo, P., and Kirchmann, H.: Decomposition of organic matter in soil as influenced by texture and pore size distribution, in: Managing Nutrient Cycles to Sustain Soil Fertility in Sub-Saharan Africa, edited by: Bationo, A., Academy Science Publishers and TSBF CIAT, Nairobi, 261–276, ISBN 9966240756, 2004.
Nyamangara, J., Masvaya, E. N., Tirivavi, R., and Nyengerai, K.: Effect of hand-hoe based conservation agriculture on soil fertility and maize yield in selected smallholder areas in Zimbabwe, Soil Till. Res., 126, 19–25, https://doi.org/10.1016/j.still.2012.07.018, 2013.
Patra, S., Julich, S., Feger, K. H., Jat, M. L., Sharma, P. C., and Schwärzel, K.: Effect of conservation agriculture on stratification of soil organic matter under cereal-based cropping systems, Arch. Agron. Soil Sci., 65, 2013–2028, https://doi.org/10.1080/03650340.2019.1588462, 2019.
Paustian, K., Lehmann, J., Ogle, S., Reay, D., Robertson, G. P., and Smith, P.: Climate-smart soils, Nature, 532, 49–57, https://doi.org/10.1038/nature17174, 2016.
Powlson, D. S., Stirling, C. M., Jat, M. L., Gerard, B. G., Palm, C. A., Sanchez, P. A., and Cassman, K. G.: Limited potential of no-till agriculture for climate change mitigation, Nat. Clim. Change, 4, 678–683, https://doi.org/10.1038/nclimate2292, 2014.
Powlson, D. S., Stirling, C. M., Thierfelder, C., White, R. P., and Jat, M. L.: Does conservation agriculture deliver climate change mitigation through soil carbon sequestration in tropical agro-ecosystems?, Agr. Ecosyst. Environ., 220, 164–174, https://doi.org/10.1016/j.agee.2016.01.005, 2016.
R Core Team: R: A Language and Environment for Statistical Computing, R Foundation for Statistical Computing, Vienna, Austria, https://www.R-project.org/ (last access: 14 February 2024), 2020.
Rumpel, C., Chabbi, A., and Marschner, B.: Carbon Storage and Sequestration in Subsoil Horizons: Knowledge, Gaps and Potentials, in: Recarbonization of the Biosphere: Ecosystems and the Global Carbon Cycle, edited by: Lal, R., Lorenz, K., Hüttl, R. F., Schneider, B. U., and Von Braun, J., Springer Science+Business Media B.V, 445–464, https://doi.org/10.1007/978-94-007-4159-1, 2012.
Sanaullah, M., Chabbi, A., Maron, P. A., Baumann, K., Tardy, V., Blagodatskaya, E., Kuzyakov, Y., and Rumpel, C.: How do microbial communities in top- and subsoil respond to root litter addition under field conditions?, Soil Biol. Biochem., 103, 28–38, https://doi.org/10.1016/j.soilbio.2016.07.017, 2016.
Shumba, A., Dunjana, N., Nyamasoka, B., Nyamugafata, P., Madyiwa, S., and Nyamangara, J.: Maize (Zea mays) yield and its relationship to soil properties under integrated fertility, mulch and tillage management in urban agriculture, South African J. Plant Soil, 37, 1–10, https://doi.org/10.1080/02571862.2019.1678686, 2020.
Shumba, A., Chikowo, R., Corbeels, M., Six, J., Thierfelder, C., and Cardinael, R.: Long-term tillage, residue management and crop rotation impacts on N2O and CH4 emissions on two contrasting soils in sub-humid Zimbabwe, Agr. Ecosyst. Environ., 341, 108207, https://doi.org/10.1016/j.agee.2022.108207, 2023a.
Shumba, A., Chikowo, R., Thierfelder, C., Corbeels, M., Six, J., and Cardinael, R.: Data for “Mulch application as the overarching factor explaining increase in soil organic carbon stocks under conservation agriculture in two 8 year-old experiments in Zimbabwe”, https://doi.org/10.18167/DVN1/VPOCHN, CIRAD Dataverse, 2023b.
Singh, G., Schoonover, J. E., Williard, K. W. J., Kaur, G., and Crim, J.: Carbon and Nitrogen Pools in Deep Soil Horizons at Different Landscape Positions, Soil Sci. Soc. Am. J., 82, 1512–1525, https://doi.org/10.2136/sssaj2018.03.0092, 2018.
Six, J., Paustian, K., and Elliott, E.: Aggregate and soil organic matter dynamics under conventional and no-tillage systems, Soil Sci. Soc. Am. J., 63, 1350–1358, 1999.
Six, J., Elliott, E. T., and Paustian, K.: Soil macroaggregate turnover and microaggregate formation: A mechanism for C sequestration under no-tillage agriculture, Soil Biol. Biochem., 32, 2099–2103, https://doi.org/10.1016/S0038-0717(00)00179-6, 2000.
Six, J., Conant, R. T., Paul, E. A., and Paustian, K.: Stabilization mechanisms of soil organic matter: Implications for C-saturation of soils, Plant Soil, 241, 155–176, https://doi.org/10.1023/a:1016125726789, 2002.
Sun, W., Canadell, J. G., Yu, L. L., Yu, L. L., Zhang, W., Smith, P., Fischer, T., and Huang, Y.: Climate drives global soil carbon sequestration and crop yield changes under conservation agriculture, Global Change Biol., 26, 3325–3335, https://doi.org/10.1111/gcb.15001, 2020.
Swanepoel, C. M., van der Laan, M., Weepener, H. L., du Preez, C. C., and Annandale, J. G.: Review and meta-analysis of organic matter in cultivated soils in southern Africa, Nutr. Cycl. Agroecosys., 104, 107–123, https://doi.org/10.1007/s10705-016-9763-4, 2016.
Swanepoel, C. M., Rötter, R. P., van der Laan, M., Annandale, J. G., Beukes, D. J., du Preez, C. C., Swanepoel, L. H., van der Merwe, A., and Hoffmann, M. P.: The benefits of conservation agriculture on soil organic carbon and yield in southern Africa are site-specific, Soil Till. Res., 183, 72–82, https://doi.org/10.1016/j.still.2018.05.016, 2018.
Thierfelder, C. and Mhlanga, B.: Short-term yield gains or long-term sustainability? – a synthesis of Conservation Agriculture long-term experiments in Southern Africa, Agr. Ecosyst. Environ., 326, 107812, https://doi.org/10.1016/j.agee.2021.107812, 2022.
Thierfelder, C. and Wall, P. C.: Effects of conservation agriculture techniques on infiltration and soil water content in Zambia and Zimbabwe, Soil Till. Res., 105, 217–227, https://doi.org/10.1016/j.still.2009.07.007, 2009.
Thierfelder, C. and Wall, P. C.: Effects of conservation agriculture on soil quality and productivity in contrasting agro-ecological environments of Zimbabwe, Soil Use Manage., 28, 209–220, https://doi.org/10.1111/j.1475-2743.2012.00406.x, 2012.
Thierfelder, C., Matemba-Mutasa, R., and Rusinamhodzi, L.: Yield response of maize (Zea mays L.) to conservation agriculture cropping system in Southern Africa, Soil Till. Res., 146, 230–242, https://doi.org/10.1016/j.still.2014.10.015, 2015.
Thierfelder, C., Chivenge, P., Mupangwa, W., Rosenstock, T. S., Lamanna, C., and Eyre, J. X.: How climate-smart is conservation agriculture (CA)? – its potential to deliver on adaptation, mitigation and productivity on smallholder farms in southern Africa, Food Secur., 9, 537–560, https://doi.org/10.1007/s12571-017-0665-3, 2017.
Thierfelder, C., Baudron, F., Setimela, P., Nyagumbo, I., Mupangwa, W., Mhlanga, B., Lee, N., and Gérard, B.: Complementary practices supporting conservation agriculture in southern Africa. A review, Agron. Sustain. Dev., 38, 16, https://doi.org/10.1007/s13593-018-0492-8, 2018.
Thorup-Kristensen, K., Halberg, N., Nicolaisen, M., Olesen, J. E., Crews, T. E., Hinsinger, P., Kirkegaard, J., Pierret, A., and Dresbøll, D. B.: Digging Deeper for Agricultural Resources, the Value of Deep Rooting, Trends Plant Sci., 25, 406–417, https://doi.org/10.1016/j.tplants.2019.12.007, 2020.
van der Pol, L. K., Robertson, A., Schipanski, M., Calderon, F. J., Wallenstein, M. D., and Cotrufo, M. F.: Addressing the soil carbon dilemma: Legumes in intensified rotations regenerate soil carbon while maintaining yields in semi-arid dryland wheat farms, Agr. Ecosyst. Environ., 330, 107906, https://doi.org/10.1016/j.agee.2022.107906, 2022.
Villarino, S. H., Pinto, P., Jackson, R. B., and Piñeiro, G.: Plant rhizodeposition: A key factor for soil organic matter formation in stable fractions, Sci. Adv., 7, 1–14, https://doi.org/10.1126/sciadv.abd3176, 2021.
Virk, A. L., Lin, B. J., Kan, Z. R., Qi, J. Y., Dang, Y. P., Lal, R., Zhao, X., and Zhang, H. L.: Simultaneous effects of legume cultivation on carbon and nitrogen accumulation in soil, Adv. Agron., 171, 75–110, https://doi.org/10.1016/bs.agron.2021.08.002, 2022.
von Haden, A. C., Yang, W. H., and DeLucia, E. H.: Soils' dirty little secret: Depth-based comparisons can be inadequate for quantifying changes in soil organic carbon and other mineral soil properties, Global Change Biol., 26, 3759–3770, https://doi.org/10.1111/gcb.15124, 2020.
Wendt, J. W. and Hauser, S.: An equivalent soil mass procedure for monitoring soil organic carbon in multiple soil layers, Eur. J. Soil Sci., 64, 58–65, https://doi.org/10.1111/ejss.12002, 2013.
Yang, L., Luo, Y., Lu, B., Zhou, G., Chang, D., Gao, S., Zhang, J., Che, Z., and Cao, W.: Long-term maize and pea intercropping improved subsoil carbon storage while reduced greenhouse gas emissions, Agr. Ecosyst. Environ., 349, 108444, https://doi.org/10.1016/J.AGEE.2023.108444, 2023.
Yost, J. L. and Hartemink, A. E.: How deep is the soil studied – an analysis of four soil science journals, Plant Soil, 452, 5–18, https://doi.org/10.1007/s11104-020-04550-z, 2020.
Short summary
Conservation agriculture (CA), combining reduced or no tillage, permanent soil cover, and improved rotations, is often promoted as a climate-smart practice. However, our knowledge of the impact of CA on top- and subsoil soil organic carbon (SOC) stocks in the low-input cropping systems of sub-Saharan Africa is rather limited. Using two long-term experimental sites with different soil types, we found that mulch could increase top SOC stocks, but no tillage alone had a slightly negative impact.
Conservation agriculture (CA), combining reduced or no tillage, permanent soil cover, and...
