Microbial biomass of different soils a decade after change in tillage system

V magistrski nalogi smo preučevali vpliv obdelave tal, teksture in globine na vsebnost organskega ogljika (Corg) in mikrobno biomaso v tleh. V letu 2020 smo izvedli enkratno vzorčenje tal na poskusu, ki traja od leta 2011 na dveh lokacijah z različno teksturo (lažja in težja). Poskus primerja oranje s plugom (O) in minimalno, plitvo obdelavo z Eversom 4-vrstnim vario diskom (E), obe obravnavanji sta bili v letu 2017 še nadalje razdeljeni na direktno setev oz. no-till (NTo in NTe). Vzorčili smo na štirih globinah (0–1 cm, 0–10 cm, 10–20 cm in 30–60 cm). Ugotovili smo, da se Corg kopiči v zgornji plasti tal (0–10 cm), z največjimi vsebnostmi Corg pri obravnavanjih z ohranitveno obdelavo tal (E in NTe): 3,08 % in 2,89 % v teksturno težjih tleh, ter 1,93 % in 1,98 % v teksturno lažjih tleh. Vpliv teksture je bil opazen na vseh globinah, vsebnosti Corg pri teksturno lažjih tleh so bile manjše za okoli 30 %. V drugem delu naše raziskave smo določili mikrobno biomaso z dvema metodama, fumigacijo s kloroformom in izolacijo skupne DNA iz tal. Rezultati obeh metod so podali podobne zaključkemikrobna biomasa je bila skoncentrirana v zgornji plasti tal (0–10 cm), večje vsebnosti smo ugotovili pri vseh treh ohranitvenih obdelavah tal (E, NTe in NTo) v primerjavi z oranjem. Razlik v mikrobni biomasi med različnima teksturama v zgornji plasti (0–10 cm) nismo ugotovili, medtem ko je bila vsebnost mikrobne biomase v spodnjih globinah (10–20 cm in 30-60 cm) večja v teksturno težjih tleh. Dokazali smo pozitivni vpliv minimalne obdelave tal na pomembna kazalnika kakovosti tal (Corg in mikrobno biomaso). V prihodnosti bi bilo smiselno preučiti pestrost in aktivnost mikrobnih združb in določiti njihovo vlogo v delovanju ekosistema tal.In this master’s thesis, the influence of tillage, texture and depth on soil organic carbon (Corg) content and microbial biomass was investigated. Soil sampling was carried out in 2020 on an experiment set up in 2011 on two sites with different textures (light and heavy). The experiment compared ploughing (O) and minimum, shallow tillage with Evers 4-row Vario Disc (E), both treatments were further divided into no-till (NTo and NTe) in 2017. Four soil depths were sampled (0–1 cm, 0–10 cm, 10–20 cm and 30–60 cm). Corg was found to accumulate in the topsoil layer (0–10 cm), with the highest Corg contents in the conservation tillage treatments (E and NTe): 3.08 % and 2.89 % in the texturally heavy soils, and 1.93 % and 1.98 % in the texturally light soils. The effect of texture was observed at all depths, with Corg contents about 30 % lower in the texture-light soils. In the second part of our study, we determined microbial biomass using two methods, chloroform fumigation and isolation of total DNA from soil. The results of both methods gave similar conclusionsmicrobial biomass was concentrated in the top layer of the soil (0–10 cm), and higher values were obtained in all three conservation soil treatments (E, NTe and NTo). The microbial biomass content was significantly higher in the soil with heavier texture compared to lighter, although in the lower depths (10–20 cm and 30–60 cm) only, while the effect of texture on microbial biomass in the top layer (0–10 cm) was not detected. We have documented a positive effect of minimal tillage methods on important soil quality indicators (Corg and microbial biomass). In the future, it would be beneficial to study the diversity and activity of microbial communities and determine their role in soil ecosystem functioning