Greenhouse Gas Emissions from Two Soils Receiving Nitrogen Fertilizer and Swine Manure Slurry

The interactive effects of soil texture and type of N fertility (i.e., manure vs. commercial N fertilizer) on N 2 O and CH 4 emissions have not been well established. This study was conducted to assess the impact of soil type and N fertility on greenhouse gas fluxes (N 2 O, CH 4 , and CO 2 ) from the soil surface. The soils used were a sandy loam (789 g kg −1 sand and 138 g kg −1 clay) and a clay soil (216 g kg −1 sand, and 415 g kg −1 clay). Chamber experiments were conducted using plastic buckets as the experimental units. The treatments applied to each soil type were: (i) control (no added N), (ii) urea‐ammonium nitrate (UAN), and (iii) liquid swine manure slurry. Greenhouse gas fluxes were measured over 8 weeks. Within the UAN and swine manure treatments both N 2 O and CH 4 emissions were greater in the sandy loam than in the clay soil. In the sandy loam soil N 2 O emissions were significantly different among all N treatments, but in the clay soil only the manure treatment had significantly higher N 2 O emissions. It is thought that the major differences between the two soils controlling both N 2 O and CH 4 emissions were cation exchange capacity (CEC) and percent water‐filled pore space (%WFPS). We speculate that the higher CEC in the clay soil reduced N availability through increased adsorption of NH 4 + compared to the sandy loam soil. In addition the higher average %WFPS in the sandy loam may have favored higher denitrification and CH 4 production than in the clay soil.