Greenhouse gas emissions from sandy soils amended with lime and gypsum under different initial soil pH and nitrogen sources

Lime (CaCO 3 ) application has led to an inconsistent mitigation of greenhouse gas emissions (GHGs) from agricultural soils. In addition, only a few studies have investigated the impact of gypsum (CaSO 4 ) on the release of GHGs. Therefore, here we investigated the impact of initial soil pH and nitrogen sources on CaSO 4 and CaCO 3 effectiveness in reducing the production of GHGs. We hypothesized that (i) liming presents the highest effectiveness in reducing GHGs when performed in acidic soil and under NO 3 − ‐N fertilizer application, and (ii) application of CaSO 4 is not effective in reducing GHG irrespective of the initial soil pH or nitrogen (N) source. Firstly, an incubation experiment was carried out to evaluate the effect of initial soil pH using acidic soil and neutral soil amended with CaSO 4 and CaCO 3 . Subsequently, a second incubation experiment was conducted to investigate the effect of N source by applying calcium nitrate and urea in an acidic soil amended with CaSO 4 , CaCO 3 and CaSO 4 + CaCO 3 . The measured variables were soil , daily and cumulative emissions of N 2 O‐N, CO 2 ‐C and CH 4 ‐C, as well as NH 4 + ‐N and NO 3 − ‐N concentrations. CaCO 3 did not affect N 2 O‐N emission under neutral soil pH, and NO 3 − ‐N fertilizer application. However, CaCO 3 increased N 2 O‐N release under acidic soil (+96%), and urea fertilizer application (+97%). Furthermore, CaCO 3 and CaSO 4 reduced CO 2 ‐C emission from the neutral pH soil by 31%, and CaSO 4 decreased the mean cumulative N 2 O‐N release from the soil fertilized with urea‐N by 43%. In conclusion, this study did not confirm liming as an alternative to reduce N 2 O‐N release under different initial soil pH and N sources. Furthermore, our results indicated that CaSO 4 may decrease GHG emissions. Finally, these results suggest caution for considering liming as a strategy to mitigate N 2 O‐N emission from agriculture.