Plant Residue and Cropping System Effects on N Dynamics in A Gray Luvisolic Soil

Soil samples from differing cropping systems were amended with 15N-labeled plant residues having varying carbon to nitrogen (C:N) ratios to quantify N dynamics in a Gray Luvisolic soil. For non-amended cropping systems a significantly greater amount of total N was mineralized from the continuous legume (CL) than from the continuous grass (CG), barley/forage (BF) rotations, or continuous barley (CB) cropping systems. The addition of the fababean (Vicia faba L.) plant residue resulted in net N mineralization from most of the cropping systems. After 20 wk, 14.0%, 10.5% and 7.1% of the 15N was mineralized from fababean, barley (Hordeum vulgare L.) and fescue (Festuca rubra L.) amended residues, respectively, when averaged across cropping systems. Key words: Crop residues, cropping systems, Gray Luvisol, N mineralization, 15N, soil amendments