Soil microbial activity under conventional and organic production of bean and maize

The objective of this study was to compare the effects of conventional and organic production system on microbial activity in the soil cultivated with bean and maize crops. The trial in Đurđevo was set up according to the conventional farming system, while organic farming system was used in Futog. Two maize hybrids and two bean cultivars were used in the trial. Soil samples were collected in two periods during 2014 (before sowing, at flowering stage of bean crops, and at 9-11 leaf stage of maize) at two depths, at both locations. The following microbiological parameters were tested: the total number of micro­organisms, number of ammonifiers, Azotobacter sp., free nitrogen fixing bacteria, fungi, actinomycetes, and activity of dehydrogenase enzyme. The results showed that the total number of microorganisms, number of free N-fixers and dehydrogenase activity were high­er within organic production, while Azotobacter sp. was more abundant in conventional production. Variations in the number of ammonifiers, fungi and actinomycetes in relation to the type of production were not obtained. Significant differences in microbial activity were also obtained between period and depths of sampling. Cilj ovih istraživanja bio je da se uporede efekti konvencionalnog i organskog sistema gajenja na mikrobiološku aktivnost u zemljištu koje je pod pasuljem i kukuruzom kao usevima. Ogled u Đurđevu postavljen je u sistemu konvencionalne poljoprivredne proizvodnje, a ogled u Futogu u sistemu organske proizvodnje. U ogledima su korišćena dva hibrida kukuruza i dve sorte pasulja Instituta za ratarstvo i povrtarstvo u Novom Sadu. Uzorci zemljišta za mikrobiološke analize uzeti su tokom 2014. godine (pre setve i u fazi cvetanja pasulja, kao i u fazi 9-11 listova kukuruza), sa dve dubine, na oba lokaliteta. Mikrobiološka aktivnost praćena je na osnovu zastupljenosti ukupnog broja mikroorganizama, amonifikatora, Azotobacter sp., slobodnih azotofiksatora, gljiva, aktinomiceta i aktivnosti enzima dehidrogenaze. Rezultati su pokazali da su ukupan broj mikroorganizama, broj slobodnih azotofiksatora i dehidrogenazna aktiv­nost bili veći u sistemu organske proizvodnje, dok su vrste iz roda Azotobacter sp. bile zastupljenije u sistemu konvencionalne proizvodnje. Nisu zabeležene razlike u brojnosti amonifikatora, gljiva i aktinomiceta u zavisnosti od sistema gajenja. Takođe, značajne razlike u mikrobiološkoj aktivnosti utvrđene su između perioda i dubine uzorkovanja.