Crop residue decomposition and nutrient release are independently affected by nitrogen fertilization, plastic film mulching, and residue type

The return of crop residues to the soil is a common agricultural management practice for nutrient recycling and carbon sequestration. It is known that nitrogen (N) fertilization can influence crop residue decomposition and nutrient release. However, it is unclear whether the effect of N fertilization interact with plastic film mulching (PFM) or residue type. We conducted a two-year field study to quantify the main and interactive effects among N fertilization (including no input (N-0), 135 kg N ha(-1) yr(- 1) (N-135), and 270 kg N ha(-1) yr(- 1) (N-270)), PFM (with and without mulching) and residue type (roots, stems, and leaves) on the decomposition and nutrient releases of crop residues in a long-term field experiment with combined mulching and fertilization treatments. We did not observe any interactive effects among N fertilization, plastic film mulching and residue type on crop residue decomposition and nutrient releases. Crop residue decomposition was delayed at N(135 )but remained unchanged at N-270 when compared to N-0. The positive correlation between decomposition and soil available phosphorus (P) suggest that soil P status played an important role for crop residue decomposition. The two levels of N fertilization both slowed down N release from crop residues, but did not change P release. PFM accelerated crop residue decomposition by 10% in the first growing season but did not affect the release of N and P. Decomposition and N release rates were higher for leaves than for roots and stems. Overall, this study highlights the independent effects of cropland management on the fate of crop residue returned to soil.