Summary-Sodium chloride, at rates up to 100 mg g- ‘, was added to a Sassafras sandy loam amended
with finely-ground alfalfa to determine the effect of NaCl on CO1 evolution, ammonification, and
nitrification in a 14-week study. A NaCl concentration of 0.25 mg g _ 1significantly reduced CO2 evolution by 16% in unamended soil and 5% in alfalfa-amended soil. Increasing NaCl progressively reduced
COz evolution, with no COz evolved from the soil receiving 100 mg NaCl g-l. A 0.50 mg NaCl g- ’ rate
was required before a significant reduction in decomposition of the alfalfa occurred. The
NOT-N’+ NOT-N content-of the soil was significantly reduced from 40 to 37pgg-’ at 0 and
0.25 mg NaCl g-‘, respectively in the unamended soil. In the alfalfa amended soil, nitrification was
signifi&ntly reduced ai 5 mg NaCl g-‘. At 10 mg NaCl g-‘, nitrification was completely inhibited, there
being only 6 and 2 pg NOT-N + NOT-N g-’ in the alfalfa amended and unamended soil, respectively.
In the alfalfa amended soil NH:-N accumulated from 6 pg g- ’ at the 0 NaCl rate to a maximum of
54 pg go’ with 25 mg NaCl g-‘. These higher NH:-N values resulted in a 0.5 unit increase in the pHw
over that of the 0 NaCl rate in the alfalfa amended soil. At NaCl concentrations above 25 mg g- ’ there
was a reduction in NH:-N. The addition of alfalfa to the soil helped to alleviate the adverse affects of
NaCl on CO2 evolution and nitrification.