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2019, Vol. 17, No. 4

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  • Kirje
    Increasing the effectiveness of aggregates for planting sugar beet stecklings to receive elite seeds
    (2019) Kostenko, O.; Lapenko, H.; Prasolov, Ye.; Lapenko, T.; Kalinichenko, A.
    Planting sugar beet stecklings with planting machine is one of the stages in the technological process of producing elite seeds. The analysis of the experience of using planting units for planting stecklings showed a number of disadvantages: poor quality of planting stecklings without spacing stability and the absence of parameter control; unregulated applying nutrients and granules of water preservation to the roots negatively affect the development of plants. The aggregate having openers of the planting device was designed, and the system of supplying the spray of nutrients and growth stimulator is envisaged. The technological process is conducted in the following way: during the movement of equilateral triangles of the planting cones mechanism the root is planted in the soil. To eliminate the drawbacks while planting stecklings, the openers of the planting device for the roots having the diameter of 50–120 mm were designed. Owing to them free falling roots in the soil is ensured and their lifting together with the cone to the soil surface is prevented. The research has shown that root plant spacing depends on the angular and forward velocities of the device. The draft resistance of furrow openers and soil compaction depend on the furrow width and depth and the distance between the axes of quadrangles and the unit rear compaction wheels. Improving the planter, taking into account biological peculiarities of plant development, meeting the requirements of energy saving and economic expediency was proved.
  • Kirje
    Theoretical research of force interaction of a flexible cleaning blade with a beet root head
    (2019) Bulgakov, V.; Ivanovs, S.; Arak, Margus; Olt, Jüri; Estonian University of Life Sciences. Institute of Technology
    The most common technology of removing the sugar beet haulm in the world is a continuous cut of the entire mass of the green haulm with further additional removal of the upper parts of the sugar beet heads, which is carried out without extracting the roots from the ground. This is the scheme according to which most top harvesting machines, manufactured in the world, now operate. However, we have found in our studies that, due to additional cutting off the upper parts of the root crop heads, up to 10% of the sugar-bearing mass is lost. Besides, there is an urgent need for immediate processing of the sugar beet root crops, as losses of the sugar juice occur, and bacteria enter inside of the root crop through the cut-off part, causing rotting. Therefore, a more favourable operation for harvesting root crop tops is not cutting off their heads but cleaning them from the residues of the foliage. In addition, the operation of cleaning the sugar beet roots from the residues of the foliage is subject to rather high requirements due to the absence of the green and dry residues on the heads of the roots, as well as the losses and damage of the root crops themselves. The purpose of this investigation is to develop a theory of the force interaction of the flexible cleaning blade with the sugar beet head in the process of its cleaning when the blade is mounted on the vertical driving shaft. The methods used of the investigation are those of modelling, higher mathematics and theoretical mechanics, as well as programming and numerical calculations on the computer. As a result of the research, an equivalent scheme was developed and a mathematical model was constructed describing the force interaction of the flexible cleaning blade with the surface of the sugar beet root.
  • Kirje
    Agrobiological evaluation of Allium ampeloprasum L. variety samples in comparison with Allium sativum L. cultivars
    (2019) Ulianych, O.; Yatsenko, V.; Didenko, I.; Vorobiova, N.; Kuhnyuk, O.; Lazariev, O.; Tretiakova, S.
    The purpose of investigation is to study the biological and morphological features, to establish the economic and valuable characteristics of the introduced and local forms of Allium ampeloprasum L. in comparison with Allium sativum L. and to study the effect of removal of the scape in the yield. The studies used field, statistical, settlement and analytical methods. The weight of the bulb without removing the inflorescence shoot of the cultivar Sofiivskyi was 28.4– 53.3 g smaller than the variety samples No. 2 and No. 3 respectively. With removing the scape the difference increased by 60.5–68.6 g. The yield of No. 2 variety sample Allium ampeloprasum L. without removing the scape was lower than the standard by 1.7 t ha-1 while the variety sample No. 3 exceeded the standard by 1.1 t ha-1 . With the removal of inflorescence shoot the yields of variety samples No. 2 and No. 3 exceeded the cultivar Sofiivskyi by 1.6 and 2.2 t ha-1 . It has been established according to the researches that introduced forms of Allium ampeloprasum L. have high indicators of economic and valuable characteristics, but they are limited in the first years of cultivation, by the period of adaptation to the new soil and climatic conditions.
  • Kirje
    Development of an efficient regeneration system for bombarded calli from immature embryos of Moroccan durum wheat varieties
    (2019) Senhaji, C.; Gaboun, F.; Abdelwahd, R.; Udupa, S.M.; Douira, A.; Iraqi, D.
    One of the biggest obstacles limiting genetic transformation of durum wheat is the lack of an efficient regeneration system for bombarded tissues. Our study aims to optimize culture conditions for regenerating bombarded calli from immature embryos of four durum wheat varieties ‘Amria’, ‘Chaoui’, ‘Isly’ and ‘Marouane’, through comparing the effects of phytohormones (IAA, zeatin and their interaction) and nitrogen amount and sources on callus induction and plant regeneration. Both tested induction media induced approximately the same rate of induced calli for all the tested varieties. However, the interaction of the induction and the regeneration media showed a highly significant effect on plantlet regeneration for all tested varieties. After bombardment, IM1/RM2 combination proved to be the favourable medium with up to 200% and 120% plantlets regenerated for ‘Chaoui’ and ‘Isly’ varieties respectively. Encouraging results obtained in this study will help to promote the research in genetic transformation and its improvement.
  • Kirje
    Adoption and advantages of eco-friendly technology application at the Shallot farming system in Indonesia
    (2019) Mahfudz, M.; Saleh, S.; Antara, M.; Anshary, A.; Bachri, S.; Made, U.; Hasanah, U.; Rauf, R.A.
    This study aimed to evaluate the benefits farmers obtained by adopting eco-friendly technologies on local shallot cultivation in Central Sulawesi, Indonesia. The technology applied includes; trap crops, biofertilizers (bokashi and mycorrhiza arbuscular) biopesticides (Beauveria bassiana and Trichoderma sp.) and plastic mulch. Ninety-nine shallot farmers were selected, consisting of 35 farmers who applied the technology (adopters) and 64 farmers who did not (non adopters). Characteristics, rates of adoption, and benefits of both groups of farmers were measured and analyzed. The results showed that the level of technology adopted by the farmers was high and supported by farmer characteristics, particularly their age and education. The application of technology increases the production of shallots and the total profits of farmers by 29.5% and 79.1% respectively. In addition, adopters can reduce the costs of chemical inputs by around 69.5%. Therefore, the technology introduced provides multiple benefits for farmers; economically and environmentally.
  • Kirje
    Effects of nitrogen, phosphorus and vermicompost fertilizers on productivity of groundnut (Arachis hypogaea L.) in Babile, Eastern Ethiopia
    (2019) Bekele, G.; Dechassa, N.; Tana, T.; Sharma, J.J.
    Though groundnut (Arachis hypogaea L.) is a main cash crop for smallholder farmers in several districts of eastern Ethiopia, its yield is very low. Farmers apply little or no fertilizers to grow the crop possibly because no generic or recommended fertilizers rates available for farmers. Therefore field experiments were conducted for two consecutive cropping seasons in Babile district, to prove the hypothesis that one of the major factors that severely reduce the yield of the crop was lack of nutrients in the soil with the objective of investigating the effects of applying mineral NP fertilizers and vermicompost on the productivity of improved groundnut variety ‘BaHa-Gudo’. The experiment was 3 × 3 × 3 factorial with three replications laid down in a randomized complete block design comprising nitrogen (0, 23 and 46 kg N ha-1 ), phosphorus (0, 46 and 92 kg P2O5 ha-1 ) and vermicompost (0, 2.5 and 5 t vermicompost ha-1 ). The data on crop growth, nodulation and yield were collected and subjected to analysis of SAS 9.2 software. Means separation were made using Duncans Multiple Range Test (DMRT) at 5% level of significance. The results revealed that growth, yield attributes, and yields were significantly (P < 0.01) affected by the main and interactions effect of the treatments. The pod yield obtained from combined application of 46: 46 kg N: P2O5 ha-1 and 2.5 t vermicompost ha-1 exceeded the pod yield produced from nil application of fertilizers by about 100%. The economic analysis also indicated that the highest marginal rate of return (671%) and net benefit ($ 1,830) ha-1 were obtained from combined application of 46: 46 kg N: P2O5 ha-1 and 2.5 t vermicompost ha-1 . From the results it could be concluded that applying the aforementioned doses of fertilizers combination would enable farmers increase productivity of groundnut so as to enhance farmers’ income and livelihoods.
  • Kirje
    The production of methane from the straw pellets with addition of enzymes
    (2019) Dubrovskis, V.; Plume, I.; Straume, I.
    Biogas production requires much cheaper raw materials. The use of straw, as not always the full use of agricultural residues, increases the methane yield in pelletised form compared to non-pelletised straw. Lack is the high ratio of carbon to nitrogen content of straw, which leads to a slow and incomplete breakdown of the matter, and less producing substances from which bacteria produce methane.Variety of additives can be used to improve anaerobic digestion process. This article shows the results of the study, where the enzymes alpha amylase and xylanase and catalysts Metaferm and Melafen mixture are used for the digestion process echancement. Investigation was provided in 16 bioreactors operated in batch mode at 38 °C. Additives were filled into 14 bioreactors and only inoculum were filled into two bioreactors for control. The yield of biogas from straw pellets without additives was 0.655 L g -1 DOM and methane 0.301 L g -1 DOM after 34 days of anaerobic digestion. The yield of biogas from straw pellets with added alpha amylase was 0.652 L g -1 DOM and methane 0.318 L g -1 DOM. The yield of biogas from straw pellets with added xylanase was 0.689 L g -1 DOM and methane 0.347 L g -1 DOM. The yield of biogas from straw pellets with added Metaferm and Melafen mixture was 0.638 L g -1 DOM and methane 0.254 L g -1 DOM. The study demonstrates that the adding of enzymes increases the production of methane.
  • Kirje
    Torrefaction – the process for biofuels production by using different biomasses
    (2019) Urbancl, D.; Krope, J.; Goričanec, D.
    Torrefaction process is a mild pyrolysis, where biomass material is converted into solid fuel with higher heating value. The results of torrefaction at different temperatures in a range from 220 to 400 °C for three varied materials, oak wood, mixed wood and dehydrated, granulated sewage sludge are presented. The torrefaction process started with warm up stage, which took place for 30 minutes, after that sample was torrefied for 2 hours at constant temperature. The process continued with cool down stage. The energy demands were covered by electric power, while the flue gasses were not integrated in the process. The influence of the operating temperatures are analysed in order to determine optimal operation parameters to get the torrefied biomass with highest calorific value. Furthermore, the optimal operation time according to the largest increase in calorific value for each material is evaluated. The results of calorific value, mass drop and chemical compositions such as elemental analyses are also presented. Results show that heating values increase with raising temperature for both wood samples. The heating values for sewage sludge increases to approximately 320 °C, after that temperature are unchangeable. Torrefied oak wood samples were more fragile at higher temperatures in comparison to raw or torrefied oak wood samples at lower temperatures. At torrefied sewage sludge samples the changes in fragility are not detected due to pre-prepared granulates of sludge.
  • Kirje
    Effect of densification variables on water resistance of corn cob briquettes
    (2019) Orisaleye, J.I.; Jekayinfa, S.O.; Pecenka, R.; Onifade, T.B.
    Solid biofuels can be used in heat and power generation applications. The utilization of agricultural residues for this purpose would be of immense benefit to rural communities of developing countries where the resource is being produced. Water resistance is a crucial property for transport and storage of biomass briquettes under moist climate conditions. In this study, the effect of process and material variables on the water resistance property of corn cob briquettes was investigated. The water resistance of briquettes produced ranged between 32.6 and 94.8% for die temperature between 90 °C and 120 °C, hold time from 7.5 to 15 minutes and die pressures between 9 and 15 MPa. A higher die temperature resulted in an increase in the water resistance of the biomass briquettes. Also, increasing the hold time improved the water resistance of the briquettes. Using a particle size less than 2.5 mm resulted in higher briquette water resistance property compared to briquettes produced from particle sizes greater than 2.5 mm. It was also shown that the effect of the interaction of the temperature with particle size on the water resistance of corn cob briquettes was statistically significant (p < 0.05).
  • Kirje
    Modelling of the bioeconomy system using interpretive structural modelling
    (2019) Kubule, A.; Indzere, Z.; Muizniece, I.
    Due to European and global resource efficiency efforts, the bioeconomy research and the search for new bioresource valorisation alternatives has become topical. Bioeconomy directly concerns such major sectors of the economy as agriculture, forestry, fishery, as well as other indirect bioeconomy sectors. However, the practical implementation of bioeconomy has had quite low implementation rate, which is partly caused by the multitude and variety of factors that affect the bioeconomy system. This paper evaluates seven bioeconomy affecting factors (particularly related to biotechonomy concept) and links between them in order to promote successful implementation of bioeconomy. To evaluate these factors interpretive structural modelling method (ISM) is used. The application of ISM method allows to not only identify the factor interaction links, but also to graphically represent their directed structure. The results show that three out of seven factors have the strongest interrelation, namely, climate change, bioresources and technologies. This research can be complimented by further adding other factors that could be influencing for bioeconomy development, for example, financial resources, human health, well-being, and so on; therefore, to reach better understanding about influential factors and bioeconomy dependency on them; also, system dynamics approach could be used in order to fully uncover the factor interaction links.
  • Kirje
    Dynamics of work accidents incidence by severity, gender and lost workdays in Estonian agricultural sector and sub-sectors in 2008–2017
    (2019) Enn, Anni; Merisalu, Eda; Estonian University of Life Sciences. Institute of Technology
    The risk of dying in a work-related accident is greatest for those employed in agricultural sector. The aim of this study is to analyse the dynamics of work accidents (WA) incidence by severity, gender and lost workdays in Estonian agriculture in 2008–2017. Method: The database of accidents in agriculture (2008–2017) was obtained from the Estonian Labour Inspectorate (ELI). Work accidents statistics is based on official reports of employers. Results: In total 1,683 non-fatal work accidents (NFA) was registered in the past decade, from which 1,235 (79.3%) were minor and 448 (20.7%) severe. In total 13 fatal work accidents (FA) have occurred, which accounts 0.8% of all the WAs (n = 1,696). Although the trends of minor and severe WA cases showed steady increase, the number of FA has remained low. A major part WAs (74%) was registered in farming and horticulture, with prevalence of minor accidents. A severe WA is likely to occur in forestry or very likely in fishery. The proportion of injured male and female was 51.8% and 48.2%, accordingly. In the farming and horticulture sector there were more accidents among women – of all the minor accidents (n = 1,235) 52.1% occurred to women. Of all the severe WAs (n = 448) 61.2% and all the fatal work accidents happened to male workers. About 2/3 of severe WAs caused sick leave 31–90 days and more. Conclusion: The number of WAs in Estonian agricultural sector show steady increase in the past decade. A major part of accidents is minor and mostly occurred in farming and horticulture, and more often with females. Severe and FAs more often occurred in forestry and fishery. Mostly the severe WAs cause long sick leave – a month or more. When to increase work accidents severity level by one step (from minor to severe), the sick leave is increasing significantly.
  • Kirje
    Holding the wheel in passenger cars in countries with driving on the right and left side depending on the driver’s side preference
    (2019) Hruška, M.; Vaculík, P.; Kůrka, M.; Hajlich, T.; Benda, P.
    This paper deals with the assessment of the differences in how passenger car drivers hold a steering wheel with left and right-side steering in specific driving modes. The findings are compared to the generally-accepted optimal position in terms of active and passive safety, as well as long-term effects on the health of the driver. The research described in this work was conducted on a sample of randomly selected drivers in the Czech Republic, the UK and Australia using electronic questionnaires. The data was then subjected to a statistical evaluation, which looked primarily at the difference between the way in which the steering wheel was held in countries with driving on the right and driving on the left. Another parameter for statistical data evaluation was the used side preference of individual drivers. On the basis of a statistical evaluation of the obtained data, it was found that there is a difference in the way the steering wheel is held in the assessed traffic situations between drivers driving on the right and drivers driving on the left. The results of this work can be used in the design process of passenger car cabins, in particular in the field of adaptation of the control devices of particular models to the needs of drivers in individual countries based on the type of traffic. The results of the work point out the necessity to make innovations in the design of passenger car cabins with regard to the type of traffic in which the vehicle will be operated, which could lead to a better application of innovations, and thereby better possibilities of positively influencing traffic safety and the health of drivers.
  • Kirje
    The effect of sowing date on cover crop biomass and nitrogen accumulation
    (2019) Toom, Merili; Talgre, Liina; Pechter, Priit; Narits, Lea; Tamm, Sirje; Lauringson, Enn; Estonian University of Life Sciences
    Cover crops are important tools for reducing nitrogen (N) leaching from the soil and improving the nutrition of cash crops. In northern regions with short autumns it is important to maximise the growing season of cover crops to achieve sufficient biomass and N accumulation. The objective of the study was to evaluate the biomass and N accumulation of cover crops at different sowing dates in August. Field experiment at Estonian Crop Research Institute was conducted in 2017 and 2018 with white mustard (Sinapis alba L.), phacelia (Phacelia tanacetifolia Benth), buckwheat (Fagopyrum esculentum Moench), berseem clover (Trifolium alexandrinum L.), field pea (Pisum sativum L.) and faba bean (Vicia faba L.). Cover crops were sown on August 3, 8, 14 and 18 in 2017 and August 3, 8, 13, 17 and 23 in 2018. The two year experiment showed that biomass and N accumulation of cover crops were reduced with delayed sowings, but the reduction mainly depended on cover crop species. White mustard, field pea and faba bean accumulated significantly higher amount of biomass and N than phacelia, buckwheat and berseem clover at all sowing dates in both years. Because of a rapid decrease in biomass, the optimum sowing time for phacelia and buckwheat should not be later than middle of August. In both year berseem clover produced the modest amount of biomass and therefore more suited as spring sown cover crop in Estonian conditions.
  • Kirje
    Enrichment of meat products with dietary fibers: a review
    (2019) Zinina, O.; Merenkova, S.; Tazeddinova, D.; Rebezov, M.; Stuart, M.; Okuskhanova, E.; Yessimbekov, Zh.; Baryshnikova, N.
    In recent years, much attention has been paid to the development of food products with properties that can promote well-being and prevent disease. Tested strategies to improve the functional value of meat products through the introduction of dietary fiber are reviewed here. Based on the literature reviewed, the addition of dietary fiber in meat products contributes to the fabrication of products which enhance physiological functions. Furthermore, fibers can be used to improve the quality and yield of meat products.
  • Kirje
    Potential social lifecycle impact analysis of bioenergy from household and market wastes in African cities
    (2019) Dunmade, I.S.
    Bioenergy is touted as a viable source of stable and affordable energy in a number of remote sub-urban centres. This study evaluates the potential social lifecycle impacts of bioenergy production from household wastes and agri-wastes in some African cities. The assessment considered the use of rotten and unsold fruits, vegetables and other related agri-wastes from central open markets in Lagos and Johannesburg as case studies. The 2009 UNEP/SETAC’s social lifecycle assessment (sLCA) guidelines and the associated sLCA methodological sheets are used to evaluate the potential social impacts of bioenergy production from agri-waste on operators/workers, the consumers, the value chain, and the local community. Preliminary results showed that it will provide a lot of benefits such as alternative employment opportunities, improved profits for small businesses, waste minimization, cleaner environment and improved communal health. It will also lead to improvement in energy supply, and alleviation of poverty. However, care has to be taken to protect the bio-digestion facility’s neighbourhood from unpleasant odour, rodents and other organisms that may attempt to feed on the rotting agri-waste. The outcome of this study provides an insight to the necessity for the development of appropriate bioenergy policy/regulation and for the need to take preemptive steps to eliminate/minimize potential negative consequences of bioenergy production on the stakeholders.
  • Kirje
    Development of symbiotic interactions in the faba bean (Vicia faba L.) roots
    (2019) Dubova, L.; Senberga, A.; Alsina, I.; Strauta, L.; Cinkmanis, I.
    Double-inoculation of faba bean (Vicia faba L.) seeds before sowing with rhizobium bacteria and mycorrhizal fungi is a known agronomic practice. It improves symbiotic nitrogen fixation and enhances legume supply with mineral elements and water. Effective symbiosis makes it possible to replace some of the required mineral fertilizer needed for plant growth with symbiotically fixed. This will ensure more environmentally friendly agricultural production. The formation of an effective symbiosis depends on a number of biotic and abiotic factors affecting the biochemical signals released by the partners. The biochemical mediator for symbiosis formation is flavonoids. The aim of this experiment was to test the effects of rhizobial and mycorrhizal inocula on symbiosis formation under different temperatures. Beans are an important source of protein for animal feed and human consumption. Four cultivars of faba beans were used - two V. faba var. minor Beck. -‘Fuego’ and ‘Lielplatone’, and two V. faba var. major Harz. - ‘Bartek’ and ‘Karmazyn’. The combination of microorganisms for seed inoculation influenced the frequency of root mycorrhization and abundance of arbuscules. The content of flavonoids in seed exudates correlated (r = 0.93) with germination temperatures. The use of mycorrhizal fungi alone or in combination with rhizobia reduced the amount of flavonoids in the bean seed exudate. In the pot experiment the amount and size of nodules significantly differed between cultivars. Use of mycorrhizal preparation mitigated the effect of inadequate germination temperature. Higher degree of mycorrhization and more intense formation of arbusculs formation was observed in the bean roots grown in vegetation pots in comparison with field ones. Local bred ‘Lielplatone’ had significantly better compatibility with microsymbionts in local agroclimatic conditions.
  • Kirje
    Physicochemical properties and agglomeration parameters of biogas digestate with addition of calcium carbonate
    (2019) Dąbrowska, M.; Świętochowski, A.; Lisowski, A.
    The aim of the work was to determine the physical properties of digestate from biogas production - either with or without the addition of calcium carbonate and to determine the parameters of its compaction. The material for research was obtained from an agricultural biogas plant specialized in processing cattle manure, vegetable pomace, chicken manure and maize silage. The parameters of compaction of digestate were experimentally determined and its net calorific value was calculated based on the gross calorific value. Physical properties were determined according to standards. The moisture content of liquid digestate was 96%. Mechanical separation allowed to decrease the water content by 19% and addition of 20% of calcium carbonate by 30%. It was found that digestate with addition of calcium carbonate is not suitable to use for energy purposes, because of its low net calorific value (5.2–5.9 MJ kg-1), however it can be used for fertilizer purposes in relation to its chemical composition. Without additives, the net calorific value was 14.9 MJ kg-1 , but due to the high moisture content of the raw material it is unprofitable to dry it and burn. On the other hand, it was proved that it is possible to obtain pellets of appropriate density out of the digestate using 40 mm of the die height and 0.3 g of single portion of the material.
  • Kirje
    Blends of unrefined vegetable oils for functional nutrition
    (2019) Simakova, I.; Volf, E.; Strizhevskaya, V.; Popova, O.; Kozyreva, V.; Karagulova, E.
    The unbalanced ratio of ω-3/ω-6 of polyunsaturated fatty acids (PUFAs) causes a number of alimentary-dependent diseases, and the intake of capsulated forms as biologically active additives does not always take into account the established eating behavior of the population and the hedonic aspect of food consumption in general. The Saratov region is one of the leading agricultural regions in the Russian Federation, one of the leaders in the cultivation and processing of low-used but valuable oily raw material, such as seeds of mustard, milkthistle, camelina, safflower. The object of the study were the above listed oils and their food compositions obtained by blending. The functionality and biological efficiency of the initial oils were investigated by gasliquid chromatography. Applying the methods of mathematical modeling, new food systems with the specified characteristics were designed (achieving the optimal ratio of ω-3: ω-6 acids). The most promising samples were selected through sensory analysis. Functional and sensory properties were taken as reference points for selection. The developed mathematical model is applicable to this food system, which was proved by the study conducted empirically. As a result of the work performed, blends of elite unrefined vegetable oils with health-promoting properties were obtained; their use in nutrition is designed to contribute to the formation of a healthy and active longevity in general, as well as to the minimizing the deficit of essential factors of nutrition in the child's body, athletes in the popular sports and sports of records.
  • Kirje
    Effect of hemp fibre length on the properties of polypropylene composites
    (2019) Alao, P.F.; Kallakas, H.; Poltimäe, T.; Kers, J.
    Hemp fibre (HF) is a natural fibre that has gained increased application in interior material for automobile industries (Sanjay, et al., 2016). However, good interfacial bonding between fibre/matrix is necessary to enhance the mechanical properties of the composite (Pickering, et al., 2007). This study focuses on the effect of fibre length, alkali and silane treatments on the mechanical and physical properties of hemp fibre reinforced polypropylene composites. Compression moulding technique was used to produce the composite, fibre lengths of 50, 100 and 150 mm were selected and combined with polypropylene powder at a fibre/PP ratio of 60/40%, a pressure of 1.67 MPa and temperature between 160–200 °C. The results obtained show that longer fibres enhanced mechanical strength. The tensile test result, for instance, shows a 21% increase in flexural strength at 150 mm compared to the fibre length of 50 mm. The modification resulted in a 46% decrease in strength, especially for 150 mm long fibres. This may have been as a result of fibre damage, inadequate modification, less quality fibre or higher initial moisture content in the modified fibres as observed from FTIR spectroscopy. Further investigation of these factors is required to be able to conclusively determine if they may have affected the mechanical performance (Alao, 2018).
  • Kirje
    Influence of organic and inorganic fertilization on soil properties and water infiltration
    (2019) Stehlík, M.; Czako, A.; Mayerová, M.; Madaras, M.
    Soil aggregate stability (SAS) belongs to the most important parameters determining the quality of soil and fertilizer influence on soil aggregation. We evaluated the relationship between SAS, hydro–physical soil properties and infiltration rates in three long–term field experiments founded in 1956 on different soils. Soil properties under three fertilization regimes– no fertilization, farmyard manure, farmyard manure and mineral fertilization–were evaluated at silty loam Chernozem, silty loam Phaeozem and sandy loam–loam Cambisol. A significant impact of fertilization on SAS was found, even though the differences in SAS were rather low. The lowest SAS was recorded at plots with manure and mineral fertilization (25.1%) compared with plots without fertilization (28.7%) and plots with manure–only fertilization (28.2%). The highest SAS (36.5%) and the highest semi–capillary porosity (SP; 11%) were observed at sandy loam–loam soil. Hydro–physical soil properties were more favourable at fertilized plots (SP 9.6% and bulk density ρb 1.31 g cm-3 ) compared with unfertilized ones (SP 8.8% and ρb 1.35 g cm-3 ). The lowest SP (8.32%) and the highest ρb (1.37 g cm-3 ) were recorded at Phaeozem, which corresponded with the lowest SAS (19.4%). Chernozem had similar soil texture to Phaeozem, but SAS (24.7%), SP (9%) and ρb (1.27 g cm-3 ) were more favourable. Despite the low level of statistical significance due to the large variation of infiltration measurements, a higher infiltration rate was recorded at fertilized plots (45 mm hour-1 ) compared to unfertilized ones (35 mm hour-1 ).