PhD students

PhD students

Jordi Escuar Gatius  
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Kerttu Tammik

kerttu.tammik@emu.ee

Supervisors:       Karin Kauer and Alar Astover
Title: Stability of soil organic matter in arable land
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Gheorghe Stegarescu (gheorghe.stegarescu@student.emu.ee)
Supervisors: Endla Reintam and Tõnu Tõnutare
Title: Factors affecting soils structural stability
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Good soil aggregate stability is an essential indicator of high organic matter and high yield. One way of increasing soil aggregate stability is to incorporate in the soil, cover crops as fresh soil organic matter. The fast decomposition of readily accessible fresh organic matter improves microbial activity and has a transient effect on aggregate stability. Also, during their growth cover crops exude root exudates (polysaccharides, lipids, etc.) which serve as an organic matter source for microorganisms. In exchange, microorganisms produce aggregates binding agents. The pathways of the organic matter sources in the soil are complex and still hard to predict. In the experiments in Estonia as well in Latvia and Lithuania the incorporation of cover crops had a negative or no effect on the soil aggregate stability. The reasons for such kind of results are still unknown. Our research project aims to identify the effect of different cover crops on the soil aggregate stability in a sandy loam soil by taking into consideration the effect of such factors as crop residues biochemical composition, soil conditions and soil biological properties.

The main research goals of the project are:

  • to study the effect of decomposition rates of different cover crops on the soil aggregate stability;
  • to evaluate the effect of plant glucosinolates compounds on the soil microbial activity and soil aggregate stability;
  • to study the role of the root exudates exuded by cover crops in soil aggregation and soil aggregate stability;
  • to investigate the effect of the soil phosphatase on the soil aggregate stability.

 

Mihkel Are mihkel.are@student.emu.ee
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Pavel Covali covali@emu.ee
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Sandra Pärnpuu (sandra.parnpuu@emu.ee)
Supervisors: Endla Reintam, Karin Kauer and Priit Tammeorg
Title: The effects of biochar on soil physico-chemical properties and efficiency of waste fertilizer
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Solutions are being sought to mitigate global warming and soil fertility decline around the world. Biochar has received a lot of attention because it makes possible to increase the soil carbon content through the bound carbon from the atmosphere. In addition, biochar has a positive effect on many physico-chemical parameters of soil. Although biochar has been studied very intensively over the last decade, its real impact to the soil properties is still unclear. The majority of previous studies have been short-term, so in their results, the effects of biochar are just after application to the soil characterised. The properties of biochar in the soil change and also the effect of biochar on soil properties may change over time when its particles are gradually distributed more evenly in the soil profile.

Until now, biochar has been used mainly either without or with some organic fertilizers. The effect of biochar on wood and oil shale ash is unknown. In Estonia, both ashes are known as lime fertilizers. The addition of biochar can broaden their spectrum of action on soil, due to the stable carbon and nutrients in the biochar, as well as the physical properties of the biochar.

This dissertation deals with i) the dynamics of the effect of biochar on the physico-chemical parameters of Luvisols on the basis of data collected from a 9-year experiment, and ii) the effect of biochar on the fertilization properties of wood and oil shale ash.

In this study we investigate:

• changes in soil porosity, water and cation exchange capacity, bulk density, aggregation, etc. during the 9 years after biochar application;

• changes in the amount and composition of functional groups on the surface of biochar in the soil;

• the effect of the addition of biochar on the release of nutrients from wood and oil shale ash, uptake by plants, and on the physico-chemical parameters of the soil.

 

  Merit Sutri  
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  Kadri Allik  
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Defended Thesis

Author Year Titel Supervisor
Kersti Vennik 2019

The effect of military vehicles on rut formation on Estonian soils and natural recovery of the ruts

Prof. Endla Reintam; Prof. Thomas Keller; Peeter Kukk
Elsa Putku 2016

Prediction models of soil organic carbon and bulk density of arable mineral soils

Prof. Alar Astover; Assoc. Prof. Christian Ritz
Diego Sanchez De Cima 2016

Soil properties affected by cover crops and fertilization in a crop rotation experiment

Assoc. Prof. Endla Reintam; Prof. Anne Luik
Liia Kukk 2012

Site-specific energy crop planning: Potential land resource, pedo-climatic And economic risks

Assoc. Prof. Alar Astover; Merrit Shansky
Katrin Trükmann 2011

 

Quantifizierung der Stabilisierungseffekte von Pflanzenwurzeln als Möglichkeit zur Reduzierung der mechanischen Bodendeformationen von unterschiedlich bewirtschafteten Grünlandstandorten

Prof. Rainer Horn; Assoc. Prof. Endla Reintam
Alar Astover 2007 Land use and soil management in Estonian agriculture during the transition from the Soviet period to the EU and its current optimisation by the spatial agro-economic decision support system Prof. Hugo Roostalu
Endla Reintam 2006 Changes in soil properties, spring barley Hordeum vulgare L.) and weed nutrition and community due to soil compaction and fertilization on sandy loam stagnic luvisol Assoc. Prof. Jaan Kuht
Prof. Raimo Kõlli, 
Valli Loide 2002 The content of available magnesium of Estonian soils, its ratio to potassium and calcium and the effect on the yield of field crops Prof. Emer. Paul Kuldkepp
Enn Leedu 1998 Possibilities to alleviate damage inflicted to Estonian agriculture through oil-shale mining Prof. Emer. Endel Kitse
Arno Kanal 1996 Organic matter turnover in arable Podzoluvisols Prof. Raimo Kõlli