Effect of Magnesium Chloride–Induced Salinity on Carbon Dioxide Evolution and Nitrogen Mineralization in a Silty Clay Loam Soil

Abstract

A laboratory incubation experiment was conducted to evaluate the effect of magnesium chloride–induced salinity on carbon dioxide (CO₂) evolution and nitrogen (N) mineralization in a silty loam nonsaline alkaline soil. Magnesium chloride (MgCl₂) salinity was induced at 0, 4, 8, 12, 16, 20, 30, and 40.0 dS m⁻¹ and measured CO₂ evolution and N mineralization during 30 days of incubation. Both CO₂ evolution and N mineralization decreased significantly with increasing salinity. The cumulative CO₂ evolution decreased from 235 mg kg⁻¹ soil at electrical conductivity (EC) 0.65 dS m⁻¹ to 11.9 mg kg⁻¹ soil at 40 dS m⁻¹ during 30 days of incubation. Similarly, N mineralization decreased from 185.4 mg kg⁻¹ at EC 0.65 dS m⁻¹ to 34.45 mg kg⁻¹ at EC 40.0 dS m⁻¹ during the same period. These results suggested that increasing magnesium chloride salinity from 4 dS m⁻¹ adversely affect microbial activity in terms of carbon dioxide evolution and N mineralization.

Keywords:

• CO₂
• magnesium chloride
• microbial activity
• nitrogen mineralization
• salinity

Acknowledgment

This study was sponsored by the Higher Education Commission (HEC), Islamabad, under the 5000 Indigenous Ph.D. Program.