Soil degradation: A global threat to sustainable use of black soils

Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production. With the ongoing intensification of agricultural practices and negative natural factors, black soils are confronting enhanced degradation. The holistic overview of black soil degradation and the underlying mechanisms for soil health improvement will be key for agricultural sustainability and food security. In this review, the current status and driving factors of soil degradation in the four major black soil regions of the world are summarized, and effective measures for black soil conservation are proposed. The Northeast Plain of China is the research hotspot with 41.5% of the published studies related to black soil degradation, despite its relatively short history of agricultural reclamation, followed by the East European Plain (28.3%), the Great Plains of North America (20.7%), and the Pampas of South American (7.9%). Among the main types of soil degradation, soil erosion and soil fertility decline (especially organic matter loss) have been reported as the most common problems, with 27.6% and 39.4% of the published studies, respectively. In addition to the natural influences of climate and topography, human activities have been reported to have great influences on the degradation of black soils globally. Unsustainable farming practices and excess in agrochemical applications are common factors reported to accelerate the degradation process and threaten the sustainable use of black soils. Global efforts for black soil conservation and utilization should focus on standardizing evaluation criteria including real-time monitoring and the measures of prevention and restoration for sustainable management. International cooperation in technology and policy is crucial for overcoming the challenges and thus achieving the protection, sustainable use, and management of global black soil resources.