Microbial residues as indicators of soil restoration in South African secondary pastures

► Amino sugars traced microbial sequestered N in South African secondary pastures. ► Amino sugar contents recovered incompletely after converting cropland to pastures. ► Clay-bounded amino sugars recovered faster and more efficiently than in bulk soil. ► Fungal glucosamine dominated the microbial N sequestration in the long-term. ► Soil microbial N cycles changed irreversibly by former intensive cropping.