engleski

Microbial abundance and activity as a response to soil covering and mineral nitrogen fertilization

Microorganisms play a key role in the soil ecosystem functioning and their role is essential in numerous soil processes. The aim of the present study was to determine the effect of soil covering with different materials and three nitrogen fertilizer rates on total number of bacteria, abundance of microorganisms involved in nitrogen cycling, abundance of cellulolytic microorganisms and dehydrogenase activity. Stationary field trial was set up on hydromeliorated terra rossa soil in Istria. Nine trial plots were formed, with three replications, which differed from one another in the amounts of nitrogen fertilizers applied as well as in soil surface covering. Sampling was carried out four times during the growing season. Effect of sampling season on total number of bacteria as well as on the abundance of nitrifiers and denitrifiers was determined. In both years, statistically significant effect of soil covering upon the cellulolytic bacteria was found. Nitrifiers were the least abundant of all examined groups of microorganisms in both years, and in 2010 significantly highest number of nitrifiers was obtained with 120 kg of nitrogen applied (in May). In June and October significantly highest number of denitrifiers was recorded in plots covered with polyethylene film. Dehydrogenase activity was highest in uncovered plots in three sampling seasons in 2010.This study revealed that soil covering and different nitrogen fertilizer rates had very different impact on total number of microorganisms and on microbiological processes involved in the nitrogen cycle.

soil microbial properties; nitrogen cycle; dehydrogenase activity; nitrogen fertilization; soil covering

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