Purpose <p>This study investigates the legacy effects of simulated acid deposition (acid rain and nitrogen deposition) on soil respiration in a subtropical slash pine (<i>Pinus elliottii</i>) plantation after deposition cessation, aiming to clarify how different deposition types and their interactions influence the recovery of soil carbon fluxes in a subtropical forest ecosystem.</p> Materials and methods <p>A field experiment was conducted in a subtropical Chinese forest, simulating various acid deposition treatments: two acidity levels of acid rain, two intensities of nitrogen deposition, their combined applications, and a cessation phase. Soil respiration and related environmental factors were monitored during one year of treatment and over four years following termination.</p> Results and discussion <p>After one year of treatment, soil respiration decreased significantly by 25.94%–55.78%. Following cessation, the inhibition gradually weakened. One year post-cessation, low-acid rain and most combined treatments showed no significant effects. By the fourth year, only the low-nitrogen with high-acid treatment still suppressed respiration (− 28.43%), while high-nitrogen with low-acid stimulated it (+ 19.09%). During deposition, nitrogen was the main inhibitor, partially counteracted by acid rain. After cessation, recovery was faster following nitrogen-only than acid rain-only termination, but slower compared to combined-deposition cessation. Low-acidity rain enhanced nitrogen’s stimulatory effect.</p> Conclusions <p>Legacy effects of acid deposition persist differentially after cessation, with low-acidity rain amplifying nitrogen-induced stimulation. Quantitative analysis identified soil temperature as a key driving factor (direct effect: 0.814), and whose influence strengthens after deposition stops. These findings provide key insights for predicting forest carbon sink recovery under declining acid deposition.</p>