CH4oxidation in two temperate arable soils as affected by nitrate and ammonium application

摘要

The short-term effect of NaNO3or (NH4)2SO4application on CH4oxidation was measured under laboratory conditions with sieved soils collected from the top layer (0–12 cm) of a loamy and a sandy soil. The soils were incubated in sealed flasks and the CH4and CO2concentrations in headspace were measured periodically. On each gas sampling date the soils were analysed for inorganic N, electro-ultrafiltration organic N, and pH. NH4+application to the loamy soil inhibited CH4oxidation entirely whereas in the untreated control soils CH4concentration decreased linearly with a rate of-41 nl CH4l-1h-1; NO3sup-application to this soil caused a small but significant reduction in CH4uptake. The CH4-oxidizing ability of the sandy soil was low, even in the control. This was mainly a result of the disturbed soil structure after sieving. Both NH4+and NO3sup-treatments completely inhibited CH4uptake in this ligh-textured soil. The adverse impact of NH4+persisted during the entire incubation, although in the loamy soil only 17 of the NH4+added was recovered after 168 h. The negative effect of NO3sup-was probably caused by an increase in osmotic potential. Immediate inhibition of CH4oxidation after inorganic N addition was demonstrated in two arable soils, although the effect was directly related only in part to soil N transformation