Reduced tillage and organic amendments can offset the negative impact of climate change on soil carbon: A regional modelling study in the Caribbean

Climate change and the ongoing development towards agriculture for the local market in the Caribbean could contribute to soil degradation in coming decades. This study assessed the potential impacts of climate change (A1B IPCC scenario), land use (local market crops vs. export crop production based on pluriannual sugarcane and banana), alternative cropping practices (reduced tillage and organic amendments) and pedoclimatic conditions on soil organic carbon (SOC) changes in the period 2015-2045. The study was carried out in the Guadeloupe archipelago, which offers a good representation of the diversity of Caribbean agriculture. Our modelling approach coupled a biophysical model of SOC dynamics with three databases accounting for land use, cropping practices and soil properties at the territory scale. The results indicated that cropping practices and land use were more important than climate change and pedoclimatic conditions in affecting SOC stocks. Despite this, in absolute terms climate change increased SOC losses at the territory scale by 29-fold, and up to 30% of these losses were linked to pluriannual sugarcane monoculture, due to the negative impact of climate change on plant growth. Most scenarios tested gave a variable degree of SOC losses (0.01 - 0.32% yr(-1) of the initial territory SOC stock). However, some cropping systems for the local market exhibited small SOC losses or slight C sequestration, mainly when reduced tillage was applied in regions characterised by high use of organic amendments. These results suggest that soil resilience to climate change under crop production for local market could be reinforced by adopting reduced soil tillage and improved organic amendment management.