Abstract:
Carbon dioxide and nitrous oxide are two important greenhouse gas that
contribute to global warming. Farmers in Northern Ghana rely on mineral fertilizers
mainly sulphate of ammonia, urea and NPK compound fertilizers to boost crop
production due to low soil fertility. A study was conducted on Ferric Luvisols in
Akukayilli in the Tolon District of the Northern Region of Ghana to assess the
influence of physic-chemical properties and environmental factors (soil
temperature and soil moisture characteristics) on CO2, N2O, NO NO2 emissions.
A randomized complete block design with three replications was used. Two
nitrogenous fertilizer sources, sulphate of ammonia and urea at two rates of 60 and
120 kg N ha-1 y-1 and NPK (60-40-40) were used. Maize was the test crop, using
the variety omankwa. The fate of excess N fertilizer in the soils were determined
by 15N procedures. Application of NPK 60-40-40, sulphate of ammonia 60 and urea
60 kg ha-1 y-1 produced substantial maize yield with minimum production of CO2
and N2O. A nitrous oxide emission factor (EF) of 0.15 % has been established for
the Northern savanna zone of Ghana. A large substrate availability (120 kg N ha-1
y-1) was found to contribute to the high emission of greenhouse gases, however, the
levels of the greenhouse gases observed in this study are below the threshold that
will lead to global warming. Observed 815N values of N2O proved that the
application of the compound fertilizer NPK fixed higher nitrogen in the soil than
sulphate of ammonia and urea. Water filled pore spaces directly correlated with
increase in emission of N gases. It is recommended that the emission factor be
assessed for soils of other agro-climatic zone.
