Effect of fertilization history on shortterm emission of CO ₂and N ₂O after the application of different N fertilizers - a laboratory study

Increasing organic carbon (OC) stocks in soils reduce atmospheric CO2, but may also cause enhanced N2O emissions. The objective of this study was to determine whether there are any differences in N2O and CO2 emissions from sandy arable soils with different soil OC and total nitrogen stocks due to the annual application of either farmyard manure (S-FYM) or mineral fertilizer (S-MIN) over 27 years. A laboratory incubation was performed to test the short-term effects of the application of different fertilizers [farmyard manure (FYM), KNO3 (MIN) and biogas waste (BW)] on N2O and CO2 emissions. The CO2 emission rates indicated that OC availability in the soil was higher after BW application than after FYM application. N2O emission for 53 days following fertilizer application amounted to 0.01% (MIN), 0.21% (FYM) and 24% (BW) of the total amount of N applied. The high emissions induced by BW were attributed to the combination of a high availability of OC and ammonium in the fermented waste. Fertilization history, which caused higher soil OC stocks in S-FYM, did not influence N2O emissions. The results suggest that characterization of C and N pools in organic fertilizers is required to assess their impact on N2O emissions.