Climate change impacts on crop production and soil carbon stock in a continuous wheat cropping system in southeast England

Understanding dynamics of soil organic carbon (SOC) stock in agroecosystems under climate change is imperative for maintaining soil productivity and offsetting greenhouse gas emissions. Simulations with the SPACSYS model were conducted to assess the effects of future climate scenarios (Representative Concentration Pathway (RCP) 2.6, 4.5 and 8.5) and fertilization practices on crop yield and SOC stock by 2100 for a continuous winter wheat cropping system in southeast England. Weather data between 1921 and 2000 was considered as a baseline. SPACSYS was first calibrated and validated with the data of the Broadbalk continuous winter wheat experiment for over a century. Six treatments were used: no fertiliser (control), a combination of chemical nitrogen, phosphorus and potassium with three N application rates (N1PK, N3PK and N5PK), manure only (FYM) and a combination of manure and chemical nitrogen application (FYMN). SPACSYS simulated grain yields and the dynamics of SOC and TN stocks well compared with the observations. Future climatescould significantly increase wheat yield by an average of 8.3% as compared to the baseline. FYMN was characterized by the highest grain yield. Moreover, when considering NPK practices, the relative increase in SOC stock under the RCP8.5 (+3.3%) was higher than those under the RCP4.5 (+1.4%), whereas the RCP2.6 indicated a negative effect (-0.6%) on SOC stocks. When considering manure amendments, the SOC stock decreased (-1.2%) under all RCP scenarios. However, continuous manure amendments can still be considered as a sustainable strategy for SOC sequestration with C stock increases between 34-106 kg C ha^-1 yr^-1. Future climates generally had positive effects on C sequestration in continuous wheat system with an annual C sink of 43-425 kg C ha^-1 yr^-1. Mineral fertiliser plus manure could be recommended as a good practice for simultaneously increasing crop productivity and having a rather high C sink under future climate change.