Vahekultuuride ja väetamise mõju mulla omadustele külvikorrakatses

A Thesis for applying for the degree of Doctor of Philosophy in AgricultureThe aim of the current study was to investigate based on a five-year crop rotation experiment (field pea, potato, barley under-sown with red clover, red clover, and winter wheat) situated in Tartu, Estonia, the impact of cover crops (oilseed-rape, rye and perennial ryegrass), alone or with cattle manure (40 t ha-1), in organic farming and mineral fertilizers (up to N150P25K95) effect in conventional farming in soil chemical (pHKCl, SOC, Ntot, available P, K, Mg and Ca) and physical properties (bulk density, porosity, water permeability and penetration resistance) since 2008 till 2014. In addition in 2013–2014 the effect of cover crop on soil aggregate stability, earthworm population and microbial activity (FDA) was also tested in organic farming. After the first rotation, the organic systems counted with the highest C input as a result of the incorporation of the main crop residues, plus the ploughing of cover crops and the yearly addition of cattle manure, resulting a positive effect on SOC and N, increasing SOC by 1.47% since experiment started. However, the larger number of tillage operations carried out in these systems counterbalanced the positive effect of cover crops and manure on the soil physical properties in the organic systems which presented the highest bulk density (1.47 Mg m-3 and 1.48 Mg m-3, respectively) and the lowest percentage of air filled pores (14.6% and 14.1% respectively) compared with the conventional fertilized systems with lower bulk density (1.39 Mg m-3), higher percentage of air filled pores (19.1%) and plant available water (22.8%). During the second period, the sum of different factors such as intensive tillage and the decrease in Mg, affected the percentage of soil stable aggregates in the organic systems with cover crops and cattle manure, decreasing it by 1.6% and 9.5% respectively. Contrary, these systems presented higher number of earthworms and the highest enzymatic activity with FDA average values of 59.7 μg and 58.4 μg fluorescein g dry soil-1 h-1, respectively, compared to the control treatment. In summary, the use of cover crops alone or with cattle manure cannot be considered sufficient for maintaining a constant concentration of nutrients and good soil physical conditions in the soil after seven years of rotation under intensive tillage and further research is needed under lower tillage intensity.Käesoleva doktoritöö eesmärgiks oli uurida viieväljalises külvikorras (hernes, kartul, oder punase ristiku allakülviga, punane ristik, talinisu) maheviljeluse tingimustes vahekultuuride (raps, raihein, rukis) ja sõnniku (40 t ha-1) ning tavaviljeluse tingimustes mineraalväetiste mõju mulla keemilistele (pHKCl, SOC, Ntot, liikuvate P, K, Ca ja Mg) ja füüsikalistele (lasuvustihedus, poorsus, veeläbilaskvus ning penetromeetriline takistus) omadustele aastatel 2008 kuni 2014. Lisaks uuriti aastatel 2013–2014 maheviljeluses vahekultuuride mõju mullaagregaatide stabiilsusele, vihmaussikooslusele ning mulla mikrobiaalsele aktiivsusele. Suurim aastane orgaanilise süsiniku (Corg) juurdetulek mulda leiti maheviljeluslike süsteemide puhul (1,47% võrra), kus põhikultuuride põhule ja juurtele lisandus vahekultuuridest ja sõnnikust tulev orgaaniline aine. Intensiivne harimine, mis kaasnes umbrohtude hävitamise ja vahekultuuride külviga maheviljeluses, vähendas vahekultuuride ja sõnniku positiivset mõju mulla lasuvustihedusele ja poorsusele terve katseperioodi jooksul, põhjustades lasuvustiheduse tõusu (vastavalt 1.47 Mg m-3 ja 1.48 Mg m-3-le) ja aeratsioonipoorsuse vähenemise (vastavalt 14.6%-le ja 14.1%le), võrreldes mineraalväetiste kasutamisega tavaviljeluses (tihedus 1,39 Mg m-3, aeratsioonipoorsus 19,1%). Nii intensiivne harimine kui ka mulla magneesiumisisalduse vähenemine võisid olla põhjusteks, miks vahekultuurid ja sõnnik ei suurendanud, vaid hoopis vähendasid (vastavalt 1,6% ja 9,5%) mulla struktuuriagregaatide stabiilsust. Vaatamata sellele suurendas vahekultuuride ja sõnniku kasutamine mulla mikrobiaalset aktiivsust ja vihmausside arvukust, võrreldes väetamata mullaga. Kokkuvõtteks ei saa pidada aga ainult vahekultuuride kasutamist või nende kasutamist kombinatsioonis sõnnikuga piisavaks mulla toitainete tasakaalu ja füüsikaliste omaduste säilitamiseks pärast 7 aastat intensiivse harimise juures ning edasised katsed väiksema harimisintensiivsuse juures on vajalikud.This research was supported by European Social Fund’s Doctoral Studies and Internationalization Programme DoRa. Publication of this thesis was supported by the Estonian University of Life Sciences

The Upper Bound Theorem in forging processes: Model of Triangular Rigid Zones on parts with horizontal symmetry

The analysis to determine the necessary forces with which to achieve a plastic deformation in metallic materials, in particular, in forging processes and under conditions of plain strain, has been raised over the years through a double approach; on the one hand, by analytical methods that involve a great complexity in their developments but that allow a direct understanding of the parameters that direct these processes. On the other hand, numerical methods, in which, thanks to the enormous development of computer technology, they provide solutions with a high approximation but, in most cases, do not allow to interpret independently the effect of each one of the parameters that come into play. The development of computers relegated analytical methods to the background. An alternative of great interest to apply these methods comes from the study of the Upper Bound Theorem by means of the Triangular Rigid Zones (TRZ) Model. One of the main limitations in the application of this model come from the fact that it is necessary to define a kinematically admissible velocity field and for complex geometric configurations of parts, this field becomes increasingly complicated. A new approach has delimited, from a theoretical perspective, a modular configuration based on a General Module formed by three TRZ that adapts to any geometry of flat surfaces of the part. Another limitation of the Upper Bound Method is the consideration of the plain strain represented by a flat section with double symmetry. Obviously, this imposition only allows to study a limited number of part configurations, which restricts its application in forging processes since the great majority of forged parts do not present geometrically this double symmetry. The present work releases one of these boundary conditions allowing to expand the possibilities of application of this method.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Observer-biased bearing condition monitoring: from fault detection to multi-fault classification

Bearings are simultaneously a fundamental component and one of the principal causes of failure in rotary machinery. The work focuses on the employment of fuzzy clustering for bearing condition monitoring, i.e., fault detection and classification. The output of a clustering algorithm is a data partition (a set of clusters) which is merely a hypothesis on the structure of the data. This hypothesis requires validation by domain experts. In general, clustering algorithms allow a limited usage of domain knowledge on the cluster formation process. In this study, a novel method allowing for interactive clustering in bearing fault diagnosis is proposed. The method resorts to shrinkage to generalize an otherwise unbiased clustering algorithm into a biased one. In this way, the method provides a natural and intuitive way to control the cluster formation process, allowing for the employment of domain knowledge to guiding it. The domain expert can select a desirable level of granularity ranging from fault detection to classification of a variable number of faults and can select a specific region of the feature space for detailed analysis. Moreover, experimental results under realistic conditions show that the adopted algorithm outperforms the corresponding unbiased algorithm (fuzzy c-means) which is being widely used in this type of problems. (C) 2016 Elsevier Ltd. All rights reserved.Grant number: 145602

Effects of organic versus conventional farming on different chemical soil parameters in Estonia

A five-year experiment results, have shown that fertilizer amendments are needed for preserving the nutrient balance in the soil. A combination of cattle and green manure, crop rotation and other organic farming practices, with chemical fertilizer amendments could suppose a sustainable solution for maintaining a correct nutrient balance in the soil in long term, better than both farming systems, conventional and organic, by separate

Talviste vahekultuuride haljasväetiseks kasvatamise mõju vihmaussidele

Vihmaussidel on oluline roll mullaviljakuse kujunemisel. Nende elutegevuse tagajärjel paraneb orgaanilise aine mineralisatsioon ja lagunemine. Vihmausse peetakse keskkonna hindamise oluliseks vahendiks tänu pidevale kontaktile mullaga, mulla vee ja selles lahustunud sooladega (Ivask, 1996). Vihmaussikoosluste ja struktuuri põhjal saab teha järeldusi põllumajandusliku tegevuse mõjust muldadele. Liikide arv, biomass ja koosluse ökoloogiline struktuur on põllumajanduslikes muldades üks olulisemaid parameetreid, määramaks mulla saastatust ja olukorda (Paoletti, 1999). Vihmausside aktiivsus ja biomass sõltub oluliselt majandamisviisist ning seeläbi mullaharimisest, orgaaniliste või mineraalsete väetiste lisamisest ning mulda viidava orgaanilise aine kogusest. Väetamine üldjuhul soodustab vihmausside levikut, kuna väetiste lisamine mulda suurendab nende toiduvaru ning loob soodsamad tingimused vihmausside arenguks. Liblikõieliste lisamine külvikorda mõjutab arvukust positiivselt (Jordan jt., 2004) ning monokultuuride kasvatamine võib olla levikut piiravaks teguriks (Ventiš., 2011). Vihmausside arvukust, massi ja mitmekesisust mõjutavaid tegureid on palju uuritud. Enamasti on peamiseks uurimisalaks mullaharimise (Peigne jt., 2009), orgaaniliste ja mineraalsete väetiste (Jordan jt., 2004) ning mahe- ja tavaviljeluse mõju vihmausside arvukusele ja biomassile (Ivask jt., 2007). Talviste vahekultuuride mõju vihmaussikooslusele on senini vähe uuritud. Antud uurimistöö eesmärgiks oli selgitada vahekultuuride haljasväetiseks kasvatamise mõju vihmausside arvukusele, massile ja liigilisele koosseisule maheviljeluslikus külvikorras

Talvised vahekultuurid parandavad külvikorras mulda

Igasuguse põllumajandustootmise, sealhulgas mahetootmise võtmeküsimuseks on kestliku mullaviljakuse tagamine. Mahetootmine põhineb kohaliku taastuva ressursi tasakaalustatud kasutusel ning mullaviljakuse tagamiseks on väga tähtis hoolikalt läbimõeldud ja kohalikesse tingimustesse hästi sobiv külvikord. Külvikorra põhikultuuride vahel on mulla orgaanika ja taimetoitainete varu täiendamiseks otstarbekas kasutada vahekultuure, mis külvatakse peale põhikultuuri koristamist. Vältimaks sügis-talvist taimetoitainete väljaleostumist tasub vahekultuurideks kasutada talvituvaid kultuure nn. talviseid vahekultuure, mis siis enne külvikorrakultuuri külvi mulda viiakse. Seega ei kasvatata vahekultuure mitte otsest müügikasu vaid esmalt ikka mullaparandamist silmas pidades, sest viiduna mulda enne põhikultuuri toimivad nad haljasväetistena (Fageria jt., 2005). Eestis on talviste vahekultuuride rolli külvikorras vähe uuritud. Käesoleva uurimuse eesmärgiks oli selgitada talviste vahekultuuride ning nende ja kompostitud lehmasõnniku mõju mullaomadustele viieväljases külvikorras erinevates maaviljelussüsteemis

Effect of green manures on weeds, crop yields and soil properties in Estonia

The aim of this research was to investigate the effect of different green manures and their combination with cattle manure on weeds, crop yields and soil properties in five-field crop rotation experiment of three different organic cropping systems

Survey and brain storming studies about machines, constructions, human and environmental risk consideration in the careers of the Universidad Politécnica of Madrid

The Universidad Politécnica of Madrid (UPM) includes schools and faculties that were for engineering degrees, architecture and computer science, that are now in a quick EEES Bolonia Plan metamorphosis getting into degrees, masters and doctorate structures. They are focused towards action in machines, constructions, enterprises, that are subjected to machines, human and environment created risks. These are present in actions such as use loads, wind, snow, waves, flows, earthquakes, forces and effects in machines, vehicles behavior, chemical effects, and other environmental factors including effects of crops, cattle and beasts, forests, and varied essential economic and social disturbances. Emphasis is for authors in this session more about risks of natural origin, such as for hail, winds, snow or waves that are not exactly known a priori, but that are often considered with statistical expected distributions giving extreme values for convenient return periods. These distributions are known from measures in time, statistic of extremes and models about hazard scenarios and about responses of man made constructions or devices. In each engineering field theories were built about hazards scenarios and how to cover for important risks. Engineers must get that the systems they handle, such as vehicles, machines, firms or agro lands or forests, obtain production with enough safety for persons and with decent economic results in spite of risks. For that risks must be considered in planning, in realization and in operation, and safety margins must be taken but at a reasonable cost. That is a small level of risks will often remain, due to limitations in costs or because of due to strange hazards, and maybe they will be covered by insurance in cases such as in transport with cars, ships or aircrafts, in agro for hail, or for fire in houses or in forests. These and other decisions about quality, security for men or about business financial risks are sometimes considered with Decision Theories models, using often tools from Statistics or operational Research. The authors have done and are following field surveys about risk consideration in the careers in UPM, making deep analysis of curricula taking into account the new structures of degrees in the EEES Bolonia Plan, and they have considered the risk structures offered by diverse schools of Decision theories. That gives an aspect of the needs and uses, and recommendations about improving in the teaching about risk, that may include special subjects especially oriented for each career, school or faculty, so as to be recommended to be included into the curricula, including an elaboration and presentation format using a multi-criteria decision model