Incorporated maize residues will induce more accumulation of new POC in HF compared with that in LF soils: a comparison of different residue types

Abstract

The distribution and dynamic of residue-derived carbon after incorporation into soil at different fertility levels have been well documented. However, the distribution of maize residue–derived C in particulate organic C (POC) from different types of organic residues in soils of different fertility levels is poorly understood. A 540-day in situ field experiment was carried out. In 2016, three types of 13C-labeled maize residues (root, stem, leaf) were added to brown earth of different fertility levels in Northeast China. 13C-POC content in the soil samples was measured on the 60th, 90th, 180th, and 540th days after in situ incubation. The results showed that 13C-POC content was significantly higher in high-fertility soil than in low-fertility soil during the whole incubation time. There were significant differences among different types of maize residues at the beginning of 180 days, with stem (0.13 g kg−1) and root (0.11 g kg−1) residues higher than leaf residue (0.08 g kg−1), and sequestration of residue in POC was similar between the roots, stems, and leaves after the 540-day field incubation. The mean residence time and residue POC in soils at each fertility level increased (P < 0.05) with increasing incubation time, with a range from 1.52 to 128.72 years in the high-fertility soil and 1.07 to 60.52 years in the low-fertility soil, but showed no significant differences among different types of maize residue. The results revealed that high-fertility soil was more conducive for new POC accumulation than low-fertility soil, and its sequestration was similar among the roots, stems, and leaves after 540 days.