Microbiological productivity of smonitza in mineral and organic fertilization conditions

Abstract

A two-year study was conducted on the effect of different rates and combinations of NPK and organic fertilizers on microbiological activity in smonitza soil under spring oats. The trial was set up at the Trial Field of the Faculty of Agronomy, Cacak, according to a randomized block design with three replications. The soil was treated by mineral and organic fertilizers. As regards the mineral fertilizers increasing nitrogen rates (N1-30 kg ha- 1, N2-60 kgha-1 i N3-90 kg ha-1) and equal P and K amounts (75 kg ha-1) were applied. As regards the organic fertilizers, solid (45 t ha-1) and liquid manure (80 t ha-1) were used. The effect of the applied fertilizers on soil microorganisms was determined twice during the growing season, by determining the total number of microorganisms and oligonitrophiles. The research results showed that the number of investigated groups of microorganisms was significantly dependent on the fertilization variants as well as on the sampling period and study year. The applied mineral fertilizers caused a decrease in the total number of microorganisms, and oligonitrophiles, particularly in the variant with the highest nitrogen rate. The inhibitory effect of the applied fertilizers was more expressed in the second sampling period. The applied organic fertilizers caused a decrease in the total number of microorganisms and oligonitrophiles, too, particularly at the end of the growing period.