Relationship of soil carbon light fraction, microbial activity, humic acid production and nitrogen fertilization in the decaying process of corn stubble

Abstract

The variation in stubble decomposition due to fertilizer incorporation was determined in a typical Argiudoll of the Argentinian rolling pampas. The experiment was conducted for 15 years, which included a no till system under maize (Zea mays L.) and a soybean rotation (Glycine max) with 0 and 45kg N ha^–1 nitrogen fertilization treatments, called NFS and FS, respectively. A higher proportion of residues with a high N content was found in the FS plots. The different substrate quality proved to be the regulating factor for mineralization. This activity was indicated by the increase in soil microbial activity and soil carbon light fraction in FS compared to NFS. This carbon light fraction mineralizes rapidly but does not contribute to the most stable components, which are related to synthesis and polymerization of humic acids. No significant differences in humic acid content were found.