Impact of agricultural intensification on soil organic carbon: A study using DNDC in Huantai County, Shandong Province, China

Abstract

Using the biogeochemical model denitrification/decomposition (DNDC), the dynamic changes of soil organic carbon (SOC) of farmland from the 1980s to 2030s were investigated in Huantai County, a typical intensive agricultural region in the Huang-Huai-Hai Plain of China. Prior to modelling, validation of the DNDC model against field data sets of SOC from Quzhou Experimental Station in the Huang-Huai-Hai Plain was conducted at the site scale. We compared the simulated results with the observed SOC in Huantai County during 1982–2011 under two different classification methods of simulation unit (the first method integrated soil type and land use of Huantai County to form the overlapped modeling units; the second selected the 11 administrative towns as the modeling units), and achieved a high accuracy in the model simulation with the improvement of the model parameters. Regional SOC (0–20 cm) density and stocks for Huantai County in the years 2012–2031 were predicted under different scenarios of farming management. Compared with current management practices, optimized fertilization (20% decrease of mineral N), crop straw incorporation (90%) and appropriate animal manure input (40 kg N ha−1 yr−1) could achieve the highest level of SOC density (56.8% higher than 2011) in the period of 2012–2031. The research highlighted the importance of crop straw incorporation, optimized N fertilization and integration of crop production with animal husbandry on the farmland carbon sequestration for maintaining a high land productivity in the Huang-Huai-Hai Plain.