magistrsko delo
Kristina Ocvirk (Author), Marjetka Suhadolc (Mentor)

Abstract

V predstavljeni nalogi smo preučevali vpliv zmanjšane intenzitete obdelave tal na velikost strukturnih agregatov, njihovo obstojnost ter na sestavo talne mikrobne združbe znotraj agregatov. Več kot dvajsetletni poskus v Moškanjcih nam je omogočal vpogled na spremembe v tleh, ki se pokažejo šele z daljšim časovnim zamikom po spremembi intenzitete obdelave. Poskus sestavljata obravnavanji konvencionalne (CT; oranje do 25 cm) in minimalne obdelave tal (MT, plitva obdelava do 10 cm, brez obračanja tal). Porušene in neporušene vzorce tal smo odvzeli februarja 2020 na dveh globinah (0-10 in 10-20 cm) v več ponovitvah. Strukturne agregate neporušenih vzorcev tal smo ločili na 3 velikostne frakcije (<2 mm, 2-4 mm in 4-8 mm); z mokrim sejanjem smo določili njihovo obstojnost. Z ekstrahiranjem skupne talne DNK smo ocenili mikrobno biomaso po treh velikostnih skupinah strukturnih agregatov ter s kvantifikacijo (qPCR) splošnih bakterijskih in krenarhejskih 16S rRNK ter glivnih ITS genov določili velikost in sestavo mikrobne združbe. Poleg tega smo določili še številčnost denitrifikacijskega gena nosZII. Rezultati kažejo, da se deleži posameznih velikostnih frakcij strukturnih agregatov med obravnavanji niso razlikovali. Se je pa večja vsebnost organske snovi na MT v globini 0-10 cm odražala v značilno večji obstojnosti strukturnih agregatov ter v večji mikrobni biomasi in večji številčnosti skupne združbe bakterij, arhej in gliv v primerjavi s CT pri tej globini. Med velikostnimi skupinami agregatov posameznega obravnavanja nismo odkrili razlik v sestavi združbe in prav tako ne med načinoma obdelave tal. Največja je bila številčnost bakterij; sledile so glive in krenarheje. Za bolj celosten vpogled bi bilo smiselno spremljati dinamiko v sestavi združb ali vzorčenje ponoviti vsaj še enkrat v času vegetacije.

Keywords

mikrobne združbe;obdelava tal;struktura tal;strukturni agregati;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [K. Ocvirk]
UDC: 631.51:631.434:631.46(043.2)
COBISS: 77738243 Link will open in a new window
Views: 230
Downloads: 37
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Other data

Secondary language: English
Secondary title: ǂThe ǂcomposition of soil microbial community in realtion to soil aggregate size and soil management
Secondary abstract: Our study examined the effects of reduced tillage intensity on the size of soil aggregates, their stability, and the composition of microbial communities within them. More than twenty years of reduced tillage in Moškanjci allowed us to evaluate the long-term effects induced by reduced tillage. Two treatments were observed, conventional tillage (CT; moldboard ploughing to 25 cm) and minimum tillage (MT; shallow non-inversion tillage to 10 cm). Composite and undisturbed soil samples from the two treatments (CT and MT) and two depths (0-10 cm and 10-20 cm) were collected in February 2020. Soil aggregates of undisturbed samples were fractionated into 3 size groups (<2 mm, 2-4 mm, and 4-8 mm). Aggregate stability was determined by the wet sieving method. Microbial biomass was estimated by the total extracted soil DNA. The abundance of the archaeal and bacterial 16S rRNA and fungal ITS genes and the denitrifier nosZII gene were determined by qPCR. The shares of selected aggregate size groups were not significantly different between treatments. However, the difference in organic matter content was reflected in aggregate stability, microbial biomass, and abundance of all studied communities which were significantly higher in MT treatment than in CT. No significant difference was observed in the fractions of the same treatment. Moreover, the ratio of microbial communities remained the same, i.e. the most abundant was the bacterial community followed by fungi and Creanarchea. For a more cohesive insight, it would be useful to conduct at least one additional sampling during the vegetation period.
Secondary keywords: microbial communities;tillage intensity;soil structure;
Type (COBISS): Master's thesis/paper
Study programme: 0
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Oddelek za agronomijo
Pages: IX, 41 f., [3] f. pril.
ID: 13555665