CO2 Emissions from Soil Under Fodder Maize Cultivation

The paper presents the results of a study aimed at assessing the total respiration of arable soil under maize fodder cultivation in the climate conditions of Central Poland over the dry growing season. The study was carried out between 22 April and 30 September 2012 (24 test dates). Total CO2-C emissions from the soil were measured in situ by means of the chamber method. The measured total CO2-C fluxes showed a high variability over the study period (3.63–302.31, mean 84.58 mg CO2-C m−2 h−1). Cumulative CO2-C soil emissions reached 3214.9 kg CO2-C ha−1 during the maize growing season and 106.8 kg CO2-C ha−1 in the post-harvest month. In the specific weather conditions of the year of the study (summer drought), CO2-C fluxes from the soil were stronger correlated with the soil NO3−-N content than with atmospheric temperature and soil moisture. The relationship between total soil CO2-C emissions and soil NH4+-N content was described by a negative correlation. Intensive CO2-C fluxes from the soil coincided with rapid maize development stages (8–15 leaf stage) and, to a lower extent, with earlier leave development stages. Total CO2-C emissions during the emergence, pre-reproductive and reproductive maize stages and, particularly, in the post-harvest period, were lower. Intensive nitrification of the soil, in dry season such as the one of 2012, could serve as an indicator of high CO2-C emissions from the soil. However, further studies are needed to confirm this finding. Decomposers probably used soil NH4+-N in the organic matter degradation process intensively and could compete with nitrifiers and maize roots for this soil source of mineral nitrogen.