Patterns and driving factors of soil organic carbon sequestration efficiency under various manure regimes across Chinese croplands

Abstract

The carbon sequestration efficiency of manure (CSE-manure) is critical for the accurate estimation of manuring-induced changes in soil organic carbon (SOC). However, the mechanisms of large-scale spatiotemporal changes in CSE-manure and their crucial drivers are unclear. To investigate these under various manure regimes, we performed field observation and collected relevant data using 1023 fields across China’s main cropland, as well as collected data on high-resolution climate and soil properties. The experimental durations significantly (P < 0.001) affected CSE-manure. The CSE-manure values were 31.4% ± 13.4 (mean ± SD), 19.2% ± 10.3%, and 16.1% ± 9.4 at the experimental durations of < 10, 10–20, and > 20 years, respectively. In addition, the manure sources significantly affected CSE-manure. The CSE-manure values of the manures from horse (27.9% ± 19.0) and sheep (26.9% ± 11.0) and farmyard manure (25.7% ± 14.8) were higher than those of the manures from pig (19.8% ± 15.4), poultry (19.1% ± 10.58), and cattle (23.1% ± 13.1). The CSE-manure values varied as per the region; the values were higher in North China than in South China. Of all the investigated variables, carbon and nitrogen input from manure, soil bulk density, annual average air temperature and precipitation, and initial SOC and soil clay content were the most important drivers of CSE-manure. The results suggested that carbon sequestration potential was higher in the northeast region. The spatiotemporal CSE-manure values under various climate conditions were predicted using trained machine learning models. Simulation results suggested that by 2100, the rate of decrease in CSE-manure will be higher at RCP (Representative Concentration Pathways) 8.5, and climate change will have a great impact on CSE-manure due to high warming effects.