Sánchez Martín, Laura and Vallejo Garcia, Antonio and Dick, Jan and Skiba, Ute M.
The influence of soluble carbon and nitrogen fertilizer on nitric oxide and nitrous oxide emissions from two contrasting agricultural soils.
"Soil Biology & Biochemistry", v. 40
Contradictory effects of simultaneous available organic C and N sources on nitrous oxide (N2O), carbon dioxide (CO2) and nitric oxide (NO) fluxes are reported in the literature. In order to clarify this controversy, laboratory experiments were conduced on two different soils, a semiarid arable soil from Spain (soil I, pH ¼ 7.5, 0.8%C) and a grassland soil from Scotland (soil II, pH ¼ 5.5, 4.1%C). Soils were incubated at two different moisture contents, at a water filled pore space (WFPS) of 90% and 40%. Ammonium sulphate, added at rates equivalent to 200 and 50 kgNha_1, stimulated N2O and NO emissions in both soils. Under wet conditions (90% WFPS), at high and low rates of N additions, cumulative N2O emissions increased by 250.7 and 8.1 ngN2O–Ng_1 in comparison to the control, respectively, in soil I and by 472.2 and 2.1 ng N2O–Ng_1, respectively, in soil II. NO emissions only significantly increased in soil I at the high N application rate with and without glucose addition and at both 40% and 90% WFPS. In both soils additions of glucose together with the high N application rate (200 kgNha_1) reduced cumulative N2O and NO emissions by 94% and 55% in soil I, and by 46% and 66% in soil II, respectively. These differences can be explained by differences in soil properties, including pH, soil mineral N and total and dissolved organic carbon content. It is speculated that nitrifier denitrification was the main source of NO and N2O in the C-poor Spanish soil, and coupled nitrification–denitrification in the C-rich Scottish soil.