Contents lists available at ScienceDirect Agricultural Systems journal homepage: www.elsevier.com/locate/agsy Soil carbon sequestration potential in a Vertisol in central India- results from a 43-year long-term experiment and APSIM modeling M. Mohanty a , Nishant K. Sinha a, ⁎ , J. Somasundaram a , Sonali S. McDermid b , Ashok K. Patra a , Muneshwar Singh a , A.K. Dwivedi c , K. Sammi Reddy d , Ch. Srinivas Rao e , M. Prabhakar d , K.M. Hati a , P. Jha a , R.K. Singh a , R.S. Chaudhary a , Soora Naresh Kumar f , Prabhat Tripathi a , Ram C. Dalal g , Donald S. Gaydon g,h , S.K. Chaudhari i a ICAR-Indian Institute of Soil Science, Bhopal 462038, India b Department of Environmental Studies, New York University, New York, USA c Department of Soil Science, Jawaharlal Nehru Krishi Vishwavidhyalya (JNKVV), Jabalpur 482004, India d ICAR- Central Research Institute for Dryland Agriculture, Hyderabad 500059, India e ICAR- National Academy of Agricultural Research Management, Hyderabad 500030, India f Centre for Environment Science and Climate Resilient Agriculture, ICAR- Indian Agricultural Research Institute, New Delhi 110012, India g School of Agriculture and Food Sciences, The University of Queensland, Brisbane, Australia h Commonwealth Scientific and Industrial Research Organisation (CSIRO), Brisbane, Australia i Indian Council of Agricultural Research, New Delhi 110012, India ARTICLE INFO Keywords: APSIM Soil organic carbon Carbon sequestration Soybean- wheat Integrated nutrient management Farrmyard manure (FYM) ABSTRACT Soil organic matter dynamics in terrestrial ecosystems are controlled by complex interactions between various factors such as climate, soil, and agricultural management practices. We utilized a process-based crop model, APSIM, to simulate long-term soil organic carbon (SOC) dynamics for a soybean-wheat cropping system under nitrogen (N) and farmyard manure management (FYM) practices for a 43-year old experimental dataset in India. The APSIM was parameterized and validated to predict grain yield and SOC stock. The validated model was then used to evaluate the impacts of different management practices on SOC dynamics in the top 30 cm of soil through scenario modeling. The results of the APSIM simulations demonstrated that improved N and FYM management practices had great potential to increase SOC sequestration in these Vertisols. The equilibrium SOC concentration under different N management practices increased with a higher N application rate, with the integrated application of N with FYM showing the maximum rate. The optimum N (N opt ) rate for maximum SOC sequestration was estimated to be 155 kg ha -1 for wheat in the studied Vertisol and the time to reach steady- state of the site was 104 years. The N opt increased SOC by about 28.6% over the initial concentration. We found that the APSIM was robust in predicting long-term changes in SOC stock (Index of agreement = 0.79 and root mean square error = 3.33 Mg ha -1 ,R 2 = 0.92, mean bias error = -1.08) for a Vertisol soil of central India, in this case under a soybean-wheat cropping system. The study results highlighted that balanced fertilization is the key to sustaining SOC stock in the long-term for Vertisols. 1. Introduction Soil organic matter (SOM) is vital for enhancing soil fertility and sustaining crop productivity. Worldwide, the largest pool of terrestrial carbon (C) is contained in soils, and under best management practices, soils may also have great potential to act as C sinks and to assist in climate change mitigation (Dalal et al., 2011; Somasundaram et al., 2017; Zomer et al., 2017; Vermeulen et al., 2019). However, historic cultivation practices, inclusive of tillage, fertilization, and other managements, have exerted significant pressure on agricultural soils' capacity to store and cycle organic C, leading to reduced soil organic carbon (SOC) stocks (Manna et al., 2013). Inappropriate management practices, coupled with deforestation and desertification, have reduced SOC by 50–70% across most agricultural soils, leaving them prone to further degradation (Lal, 2004; Sanderman et al., 2017). The restora- tion of degraded agricultural soils through appropriate land use and improved management practices can reverse the land degradation process and increase the SOC sequestration rate (Lal, 2004; Vermeulen https://doi.org/10.1016/j.agsy.2020.102906 Received 11 September 2019; Received in revised form 14 July 2020; Accepted 14 July 2020 ⁎ Corresponding author at: Department of Soil Physics, ICAR-Indian Institute of Soil Science, Bhopal 462038, India. E-mail address: nishant.sinha@icar.gov.in (N.K. Sinha). Agricultural Systems 184 (2020) 102906 0308-521X/ © 2020 Elsevier Ltd. All rights reserved. T