Plant residue quality influences the response of nitrogen mineralization to salinity

Abstract

Initial composition of plant residues determines the rate at which nitrogen (N) mineralizes or immobilizes in plant residue-amended soils. The interaction between plant residue quality and salinity effects on nitrogen mineralization/immobilization is not well understood. A laboratory experiment was conducted to study the effects of salinity stress on N transformations in a soil amended with plant residues of different initial quality. Results indicated that, N concentration of the plant residues were correlated with net rates of N mineralization/immobilization (Nm/i), regardless of salinity level. Salinity stress dissimilarly influenced the N transformation processes in soils received residues of different composition. While Nm/i was not significantly decreased due to salinity in wheat- and barley roots-amended soils, other plant residue-treated soils were significantly affected by varying degrees. Our results imply that, salinity stress can only influence N transformations in residue-amended soils, when the process is not already limited by the biodegradability of the substrates.

Keywords:

• Salinity stress
• N mineralization
• N immobilization
• plant residue

Acknowledgements

The authors wish to thank Isfahan University of Technology for funding the project.