Volume 14 (2016)
  Number 2

Journal Full Text: Vol14No2

Contents


Pages

309–316 I. Alsiņa, M. Dūma, L. Dubova, A. Šenberga and S. Daģis
Comparison of different chlorophylls determination methods for leafy vegetables
Abstract |
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Comparison of different chlorophylls determination methods for leafy vegetables

I. Alsiņa¹*, M. Dūma², L. Dubova¹, A. Šenberga¹ and S. Daģis³

¹Latvia University of Agriculture, Faculty of Agriculture, Institute of Plant and Soil
Sciences, Strazdu 1, LV-3004 Jelgava, Latvia
²Latvia University of Agriculture, Faculty of Food Technology, Department of
Chemistry, Liela 2, LV-3001 Jelgava, Latvia
³Latvia University of Agriculture, Faculty of Information Technologies, Liela 2,
LV-3001 Jelgava, Latvia
*Correspondence: Ina.Alsina@llu.lv

Abstract:

Modern agricultural farming requires precise, quick and nondestructive methods for determination of basic plant physiological parameters. One of the widely used and informative parameters is chlorophyll content in plant leaves. Determination of chlorophyll content by nondestructive methods is well elaborated for main field crops, but these methods are not widely used for chlorophyll content determination in leafy vegetables. The aim of the study was to compare two nondestructive methods with a classic biochemical chlorophylls determination method. Pigment content was expressed regarding to the leaf weight and leaf area. For nondestructive chlorophyll determination were used: a low cost handheld chlorophyll meter atLEAF+ and Miniature Leaf Spectrometer CI-710 (CID- Bio-Science). Chlorophylls content was determined using one of the 21 indices incorporated in Cl-710. For comparison of methods four different plant species (lettuce, leaf mustard, radish and cabbage) were used. Plants were grown at four illumination conditions – natural light, illumination supplemented with red, blue and mixed red/blue LED light. Results showed that at the majority of the investigated wavelengths, readings of the chlorophyll meter atLEAF+ and indices used for calculation are more sensitive to chlorophyll a content calculated per unit area. The maximum sensitivity of reflectance to variation with pigment content is found at 605 nm and 696 nm and in the near infrared region (740–930 nm). Higher correlation between non-destructive methods and biochemical analyses was observed in radish and leaf mustard leaves. The highest correlation coefficient was obtained with Difference Vegetation Reflectance index (NDVI) and Simple Ratio Pigment Index (SRPI). Nondestructive chlorophyll determination with chlorophyll meter atLEAF+ and Miniature Leaf Spectrometer CI-710 can completely replace biochemical analyses.

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317–326 N. Borys and A. Küüt
The influence of basic soil tillage methods and weather conditions on the yield of spring barley in forest-steppe conditions
Abstract |
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The influence of basic soil tillage methods and weather conditions on the yield of spring barley in forest-steppe conditions

N. Borys¹* and A. Küüt²

¹National Science Center, Institute of Agriculture NAAS Ukraine,
Mashinostroiteley Str. 2b, UK 08162 habany, Ukraine
²Estonian University of Life Sciences, Institute of Technology, Kreutzwaldi 56,
EE51014 Tartu, Estonia
*Correspondence: agrokaktys@mail.ru

Abstract:

The research on the effect the main methods of soil treatment have on its hydrophysical properties was carried out as a stationary experiment at the National Scientific Centre, Institute of Agriculture NAAS. It included a grain crop rotation with the subsequent crop sequencing: winter wheat/grain maize/barley. In 2013–2015, the spring barley variety ‘Solntsedar’ was sown. Throughout the three years of research, the consistency of the effect of the main soil treatment methods on the overall yield stayed more or less the same. Reduction in barley grain yield against the backdrop of long-term disking at the depth of 10–12 cm is explained by the thickening of the 10–30 cm layer of soil to the critical level of 1.57 g cm-3, moisture deficiency, as a result of the over-compaction of the root layer, and an increase in the amount of sterile spikelets. As the result of our research, we have come to a conclusion that for barley, soil disking at the depth of 10–12 cm is as good as ploughing if it is used as a part of differential treatment system, which includes ploughing at the depth of 28–30 cm or chisel tilling at 43–45 cm for its preceding crops. If disking was used for all crops of the grain crop rotation, a deterioration of hydrophysical properties was observed in the barley field, which can lead to a considerable reduction in the barley yield, especially in a dry cultivation year. 

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327–336 A. Brunerová, J. Pecen, M. Brožek and T. Ivanova
Mechanical durability of briquettes from digestate in different storage conditions
Abstract |
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Mechanical durability of briquettes from digestate in different storage conditions

A. Brunerová¹*, J. Pecen², M. Brožek¹ and T. Ivanova²

¹Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Material Science and Manufacturing Technology, Kamýcká 129, CZ 165 00 Prague,
Czech Republic
²Czech University of Life Sciences Prague, Faculty of Tropical AgriSciences,
Department of Sustainable Technologies, Kamýcká 129, CZ 165 00 Prague,
Czech Republic
*Correspondence: brunerova@tf.czu.cz

Abstract:

A present research was conducted to determine mechanical durability of digestate briquettes and potential influence of different storage condition. Experiments were performed on briquette samples produced from digestate feedstock with moisture content of 8.2%, ash content of 10.9% and gross calorific value of 17.15 MJ kg-1 by hydraulic piston press with working pressure of 18 MPa with external diameter 50 mm and length 40–60 mm. Briquette samples were divided into two groups and stored inside and outside building. Both groups were subjected to five experimental testing during specific time period from May until late November 2014. Mechanical durability of each briquette was measured after every testing, subsequently overall mechanical durability of specific groups was calculated. Results showed the lowest mechanical durability after first measurement: 98.85% for Group 1 and 98.95% for Group 2. The biggest change in mechanical durability was observed between first and second testing, values of following measurements were approximately equal. The highest mechanical durability was achieved after fifth testing: 99.65% for Group 1 and 99.63% for Group 2. It implied mechanical durability equal to 99.44% for Group 1 and 99.45% for Group 2 in average. Research proved very high mechanical durability which corresponds to the highest category of this quality indicator given by standard EN ISO 17225-1. Difference between mechanical durability of groups stored in different conditions was considered as minor. Thereby briquettes made from digestate are not only secondary product of proper waste management, effectively modified fertilizer but as was found by results of this research it is also suitable fuel with outstanding mechanical properties.

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337–344 J. Čedík,, M. Pexa, J. Chyba, Z. Vondrášek and R. Pražan
Influence of blade shape on mulcher blade air resistance
Abstract |
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Influence of blade shape on mulcher blade air resistance

J. Čedík¹,*, M. Pexa¹, J. Chyba², Z. Vondrášek³ and R. Pražan⁴

¹Czech University of Life Sciences, Faculty of Engineering, Department for Quality
and Dependability of Machines, Kamycka 129, CZ 165 21 Prague 6, Czech Republic
²Czech University of Life Sciences, Faculty of Engineering, Department of Agricultural
Machines, Kamycka 129, CZ16521 Prague 6, Czech Republic
³Czech University of Life Sciences, Faculty of Engineering, Department of Electrical
Engineering and Automation, Kamycka 129, CZ 165 21, Prague 6, Czech Republic
⁴Research Institute of Agricultural Engineering, p.r.i., Drnovská 507,
CZ 161 01 Prague 6, Czech Republic
*Correspondence: cedikj@tf.czu.cz

Abstract:

Mulching is an energy-intensive agricultural operation. The efforts to reduce the energy intensity makes the designers explore new solutions which would reduce the energy intensity. One of the possibilities to reduce the energy intensity of mulching is to use a work tool of different shape. The paper introduces comparison of several shapes of blades intended for the mulcher with vertical axis of rotation, where especially the rake and cloth angle is changed. The measurement was performed by means of a laboratory model of a one mulcher rotor and in the field conditions where the mulcher Bednar MZ 6000 with a range of 6 m and three rotors had been used. The measurement was performed particularly from the point of view of the energy loss caused by drag of knives. The measurement done by means of the model of the mulcher has confirmed the hypothesis that larger cloth causes increased resistance of the mulcher and higher rake angle results in decreased mulcher resistance. However, larger cloth may contribute to better work quality in the field conditions.

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345–358 A. Cekuls, H. Kalkis and Z. Roja
The impact of information technologies upon the social interaction culture among employees in Latvian enterprises
Abstract |
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The impact of information technologies upon the social interaction culture among employees in Latvian enterprises

A. Cekuls¹*, H. Kalkis² and Z. Roja³

¹University of Latvia, Faculty of Economics and Management, Department of
Management, Aspazijas blvd. 5, LV-1050, Riga, Latvia
²Riga Stradins University, Faculty of European Studies, Dzirciema street 16,
LV-1007 Riga, Riga, Latvia
³University of Latvia, Faculty of Chemistry, Ergonomic Research centre,
Jelgavas street 1, Riga LV-1004, Latvia
*Correspondence: andrejs.cekuls@lu.lv

Abstract:

The purpose of this paper is to explore the impact of information technologies upon the social interaction culture among employees in Latvian enterprises. To transform the available data and information into a valuable form for decision–making and subsequent actions, organisations have to provide an efficient communication circulation system, which is directly affected by each company’s social interaction culture. Based on previous study results in Latvia the problem of the research is to reveal and assess how to increase mutual confidence among colleagues and encourage to share of information. Tasks of the study were to research the basis of the review of scientific sources and to study the organisational and individual factors affecting employees’ perceptions regarding the role of information technologies in the information sharing process in Latvian organisations. The research showed that in organisations with positive social interaction culture, employees and supervisors socialize, interact and share information much more frequently in a verbal form, which promotes a sense of adherence to the organisation; information technologies, for their part, are used for creation of database and distribution of formal instructions.

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359–366 B. Cemek, E. Kucuktopcu and Y. Demir
Determination of spatial distribution of ammonia levels in broiler houses
Abstract |
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Determination of spatial distribution of ammonia levels in broiler houses

B. Cemek*, E. Kucuktopcu and Y. Demir

Ondokuz Mayis University, Faculty of Agriculture, Department of Agricultural
Structures and Irrigation, TR 55139 Samsun, Turkey
*Correspondence:bcemek@omu.edu.tr

Abstract:

Ammonia concentration plays a significant role in broiler performance. High concentration of ammonia impairs the immune system and increases cases of respiratory disease in birds. Ammonia concentration can be reduced using various chemical additives such as zeolite. In the present study, spatial variability of ammonia concentration was investigated and analysed in two broiler houses. In House 1 (H1) sawdust only was used as litter material whilst sawdust used together with zeolite was used in House 2 (H2). Ammonia concentration measurements were taken from 21 points in each of the broiler houses. The readings were recorded at on a weekly basis using birds’ height as height measurement bases. In order to create spatial distribution maps, Inverse Distance Weighted (IDW) and Radial Basis Functions (RBF) methods were used and analysed. The performances of these techniques were assessed by using validation test methods (root mean square error (RMSE) and mean absolute error (MAE)) with the best performing method (lowest RMSE and MAE) being selected for creating ammonia spatial distribution maps. The results indicated that spatial ammonia distribution is more uniform in H2 compared to H1. It was also observed that ammonia levels were lower in H2 than H1. The presence of zeolite as a litter addition can be attributed to study findings positively affected the broiler performance. It was considered that using zeolite with sawdust as litter material significantly reduced ammonia concentration. In H1, higher ammonia concentrations of greater than 25 ppm were recorded near ventilation fans and at the centre of the house. Because of this it is recommended to install additional fans at middle of the house for remove harmful ammonia.

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367–371 J. Hart and V. Hartová
Development of a system for locating of persons by triangulation
Abstract |
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Development of a system for locating of persons by triangulation

J. Hart¹* and V. Hartová²

¹Czech University of Life Sciences Prague (CULS), Faculty of Engineering, Department
of Technological Equipment of Buildings, Kamýcká 129, CZ165 21 Prague,
Czech republic
²Czech University of Life Sciences Prague (CULS), Faculty of Engineering, Department
of Vehicles and Ground Transport, Kamýcká 129, CZ 165 21 Prague, Czech republic
*Correspondence: janhart77@gmail.com

Abstract:

Systems that monitor movement of persons are closely linked to ensuring the security of the entire monitored complex. The security of the buildings is mediated via different types of systems such as I&HAS, CCTV, EFS, and others. These systems are combined with each other in order to achieve more optimal security of the guarded building. Patrol, attendance and other surveillance systems that do not provide the exact location of a person via coordinates are also used to monitor specific groups of people. For this reason, our goal is to design a system that is able to locate the monitored person (employee) in the building with minimal deviation.

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372–376 J. Hart and V. Hartová
New security elements in biometric systems and systems I&HAS
Abstract |
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New security elements in biometric systems and systems I&HAS

J. Hart¹* and V. Hartová²

¹Czech University of Life Sciences Prague (CULS), Faculty of Engineering,
Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 21 Prague,
Czech republic
²Czech University of Life Sciences Prague (CULS), Faculty of Engineering, Department
of Vehicles and Ground Transport, Kamýcká 129, CZ165 21 Prague, Czech republic
*Correspondence: janhart77@gmail.com

Abstract:

New security features or upgrades to existing features in biometric and security alarm systems and emergency formed at the Czech University of Life Sciences Prague, mainly due to the teaching of subjects with similar themes. When developing new technologies also help us grants, personal experience with a real installation, cooperation with manufacturers (or with distributors) security systems and a testing ground for current security features.

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377–391 G. Hrenov, Õ. Paas, P. Tint and K. Reinhold
Workers’ representation in OHS activities: Example of Estonian industrial sector
Abstract |
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Workers’ representation in OHS activities: Example of Estonian industrial sector

G. Hrenov, Õ. Paas, P. Tint* and K. Reinhold

Tallinn University of Technology, Ehitajate 5, EE19086 Tallinn, Estonia
*Correspondence: piia.tint@ttu.ee

Abstract:

The safety level in 11 Estonian enterprises was investigated. Some of them have implemented OHSAS 18001 or belong to foreign corporations. These enterprises have generally good or very good safety level. The larger the enterprise is, the better are the possibilities to give regular training for the work environment representative (WER) in occupational health and safety. The study includes quantitative and qualitative study. The MISHA method is used as the tool for quantitative study. The parts from the interviews with the enterprises representatives’ (management and employees) concerning the role of the WER in the safety performance (qualitative study) are included. The clarification and appropriate application of the WER’s role and position are the key elements to raise the safety level at enterprises. Two hypothesis: 1) on the connections between the real and formal safety elements concerning WERs and 2)  OHSAS 18001 implementation effectiveness on safety activities (including WERs’ role improvement) were proved with statistics: Factor analysis were carried out with KMO and Barlett’s test, ANOVA and T-square test with Wilks’ Lambda row.Additionally, knowledge management in safety may enhance the activities among WERs and thus, increase the safety performance in enterprises.

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392–399 J. Hůla and P. Novák
Translocation of soil particles during primary soil tillage
Abstract |
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Translocation of soil particles during primary soil tillage

J. Hůla* and P. Novák

Czech University of Life Sciences Prague, Faculty of Engineering, Kamycka 129,
CZ 165 21 Prague 6 – Suchdol, Czech Republic
*Correspondence: hula@tf.czu.cz

Abstract:

The loss of soil particles due to water erosion is a crucial problem of current farming on the soil. However, soil tillage may also contribute to the undesirable transport of soil particles. It is to note that the effects of particular working elements used on implements for soil tillage have not been described in a sufficient way. To determine the translocation of soil particles, measurements were done in the Central Bohemian region. Three basic machines for soil tillage were used for measurements: disc tiller, tine cultivator and five-share plough. Measurements were performed on sandy-loamy Cambisol after harvest of a spring cereal crop. White limestone grit was used for the indication of soil particle translocation. Great translocation of soil particles was observed after soil tillage with tine cultivator and mouldboard plough – the average translocation rates ranged between 0 and 0.9 m. Disc tiller displaced the soil particles into smaller distance (into 0.3–0.45 m). The dependence of tracer weight on a distance from the original location could be described for disc tiller and tine cultivator by an exponential function. The type of soil particle translocation by a mouldboard plough was completely different from the translocation by a disc tiller and tine cultivator. Topsoil turning over by a plough showed the lengthwise and crosswise movement of tracers with a typical dependence of their weight on a distance from the original  location. The dependence of tracer weight on a distance from the original location could be described for mouldboard ploug by an quadratic function. Individual machines for primary tillage have a different character of translocation of soil particles.

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400–406 V. Hönig, Z. Linhart and M. Orsák
Effect of gasoline contamination on the quality of arctic diesel fuel
Abstract |
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Effect of gasoline contamination on the quality of arctic diesel fuel

V. Hönig¹*, Z. Linhart² and M. Orsák¹

¹Czech University of Life Sciences Prague, Faculty of Agrobiology, Food and Natural
Resources, Department of Chemistry, Kamýcka 129, CZ16521, Prague 6, Czech Republic
²Czech University of Life Sciences Prague, Faculty of Economics and Management,
Department of Management, Kamýcka 129, CZ16521, Prague 6, Czech Republic
*Correspondence: honig@af.czu.cz

Abstract:

Fuel quality is affected predominantly during its transport between producer and user as hired transporting companies may use one transport vehicle for more different fuels. Therefore, gasoline from previous transport may cause contamination of diesel fuel in next transport. Many drivers add gasoline as additive to diesel fuel to improve start of engine avoiding difficulties of cold winter temperatures. Therefore, the objective of this article is to assess maximum gasoline content added still compliant with default values of standard EN590 and values certified by producer. Only 2% maximal gasoline content in arctic diesel fuel was found safe for both machine and operator. Distillation curve, kinematic viscosity, density, lubricity and cetane index were influenced unimportantly. Cloud point, CFPP were not changed at all.

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407–417 A. Jansons, U. Neimane, B. Dzerina and A. Adamovics
Influence of lammas shoots on height of young Scots pines in Latvia
Abstract |
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Influence of lammas shoots on height of young Scots pines in Latvia

A. Jansons*, U. Neimane, B. Dzerina and A. Adamovics

Latvian State Forest Institute ‘Silava’, Rigas 111, LV2169 Salaspils, Latvia
*Correspondence: aris.jansons@silava.lv

Abstract:

Scots pine is a commercially important tree species in northern Europe. Climate changes in combination with genetics cause differences in the tree growth rhythm, including the formation of lammas shoots. The aim of the study was to assess the relation between the occurrence of lammas shoots and the height of young Scots pines and its implications in tree breeding. Tree height was repeatedly measured, and the presence of lammas shoots was assessed at the end of the 4th through 8th growing seasons in two open-pollinated progeny trials (Daugmale and Norupe, both including the same 61 families) in the central part of Latvia. The proportion of trees with lammas shoots (max. 23%) decreased over the observation years. In both trials, at the age of 7 years, trees that had formed lammas shoot during at least one of the observed years were significantly (P < 0.001) higher than trees with no lammas shoots: 226 ± 3.5 cm vs 213 ± 3.3 cm in Norupe and 146 ± 3.9 cm vs 121 ± 1.9 cm in Daugmale, respectively. When only dominant trees (1,000 ha-1) were considered, the height superiority of trees with lammas shoots remained in Daugmale (trial with highest proportion of trees with lammas shoots), but not in Norupe. The earliest formed lammas shoots (assessed in the 4th growing season) had the strongest effect on the tree height. A correlation between the mean height and the proportion of trees with lammas shoots in the particular family was not found (P > 0.05).

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418–427 A. Kasiuliene, V. Paulauskas and J. Kumpiene
Influence of nitrogen fertilizer on Cd and Zn accumulation in rapeseed (Brassica napus L.) biomass
Abstract |
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Influence of nitrogen fertilizer on Cd and Zn accumulation in rapeseed (Brassica napus L.) biomass

A. Kasiuliene¹*, V. Paulauskas¹ and J. Kumpiene²

¹Aleksandras Stulginskis University, Institute of Environment and Ecology,
Studentu str. 11, Akademija, LT-53361 Kaunas dist., Lithuania
²Lulea University of Technology, Department of Civil, Environmental and Natural
Resources Engineering, SE 971 87 Lulea, Sweden
*Correspondence: alfreda.kasiuliene@gmail.com

Abstract:

Diffuse soil contamination with heavy metals and Cd in particular is a matter of serious concern. Application of conventional remediation methods usually is not feasible due to the large territories and relatively low heavy metal content. Thus, phytoremediation is seen as an alternative. Rapeseed was grown on Cd and Zn contaminated as well as clean soil under the greenhouse conditions. Solid and liquid nitrogen fertilizers were applied during the pot experiment in order to test their influence on heavy metal accumulation in plant tissues. Vegetative parameters were measured four times during the pot experiment and it was concluded, that the elevated concentrations of Cd and Zn in the soil did not disrupt the development of rapeseed plants. Furthermore, plants from contaminated soil produced significantly bigger seeds in comparison to plants from uncontaminated soil. Calculated Bioconcentration factors for rapeseed grown on Cd and Zn contaminated soil in all cases were below unity, thus possibility to use this plant species for phytoextraction purposes is limited, but it can be successfully grown on contaminated land as an energy crop. Application of nitrogen fertilizers had a significant effect on heavy metal accumulation and decreased Cd and Zn concentrations in rapeseed roots and stems with leaves were recorded. Accumulation differences between the liquid and solid fertilizer applications were negligible.

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428–433 H. Kirnak and Y. Akpinar
Performance Evaluation of TDR Soil Moisture Sensor
Abstract |
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Performance Evaluation of TDR Soil Moisture Sensor

H. Kirnak* and Y. Akpinar

University of Erciyes, Faculty of Agriculture, Department of Biosystem Engineering,
TR 38039 Talas, Turkey
*Correspondence: hkirnak@yahoo.com

Abstract:

Optimization of irrigation scheduling and water management greatly benefit from soilmoisture sensors that accurately measure soil water content since accuracy of soil moisture sensordirectly affects the irrigation efficiency. In this study, a performance evaluation of TDR-Slammerwith a 40 cm waveguide was done under field conditions. Experimental data were collected in adrip irrigated pumpkin (Cucurbita pepo L.) field, Kayseri, Turkey during the 2015 growingseason. Measured soil water content values on a loamy soil were compared with correspondingvalues derived from gravimetric samples. Results showed that TDR-Slammer could be safelyused as an acceptable, reliable and accurate method for measuring soil water content on loamy soils.

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434–441, S. Kovář, P. Kovaříček, P. Novák and M. Kroulík
The effect of soil tillage technologies on the surface of the infiltration speed of water into the soil
Abstract |

The effect of soil tillage technologies on the surface of the infiltration speed of water into the soil

S. Kovář, P. Kovaříček, P. Novák and M. Kroulík

Czech University of Life Sciences Prague, Faculty of Engineering, Kamycka 129,
CZ 165 21 Prague 6 – Suchdol, Czech Republic
*Correspondence: kovars@tf.czu.cz

Abstract:

Water erosion is a problem of global significance. Water erosion causes destruction or damage to enormous areas of agricultural land every year (Morgan, 2005). Agricultural land in the Czech Republic is largely exposed to the risk of water erosion on grounds of habitat, but as well agro technology. More than half of agricultural land is endangered by water erosion in the Czech Republic (Janeek, 2005). Due to water erosion the soil is depleted of its most fertile part – topsoil. The physical and chemical properties of the Earth’s surface are deteriorating, the content of nutrients and humus in the soil reduce, and the thickness of the soil profile decreases. However the grimness increases and prevents the growth of vegetation. The field trial was set up to evaluate the tillage technology. The measurements were carried out in Nesperská Lhota. The experiment was placed into a sandy loam Cambisol. The measurements took place in four variants of field trial which differed in soil tillage for maize. It was a different method combination of no-till and plough tillage. The simulation of intense rain was used to measure. A square area of the size 0.5 sq m was surrounded by sheet metal strips around the whole perimeter. The pantograph was placed on their underside and collected the runoff water. The soil washout was collected into the pipe and then into a graduated container. The surface runoff was collected in the container and weighed on automatic scales. Its values were recorded on a portable computer. The result of the measurement showed the difference between the various types of tillage. The beginning of the surface runoff at conventional tillage with ploughing was the shortest of all the variants. While the beginning of the surface runoff was reduced significantly longer by reduce tillage than by conventional tillage with ploughing. The results of the surface runoff speed and the speed of infiltration of water into the soil at the simulation of intense rains are in compliance with the results of those authors who report significant benefits of soil conservation tillage technology. This technology reduced the surface water runoff during the intense rainfall and increased water
infiltration into the soil.

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442–449 M. Kroulík, J. Hůla, A. Rybka and I. Honzík
Seed passage speed through short vertical delivery tubes at precise seeding
Abstract |
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Seed passage speed through short vertical delivery tubes at precise seeding

M. Kroulík*, J. Hůla, A. Rybka and I. Honzík

Czech University of Life Sciences Prague, Faculty of Engineering, Kamýcká 129,
CZ 165 21 Prague 6 – Suchdol, Czech Republic
*Correspondence: kroulik@tf.czu.cz

Abstract:

The development trend of precision seed machines is the use of central seed hopper. Another requirement is to increase the driving speed during precise sowing up to 10–12 km h-1. This involves increased demand for uniformity of the seeds movement between the dosing mechanism and seed coulters. Previous measurements of seed passage speed showed undesirable changes in distance of seed during passage by long delivery tubes. The research was therefore focused on the evaluation of flyby seed parameters in short vertical delivery tubes of inner diameter 10, 12 and 14 mm and a length of 0.50 m. The aim of the experiment was to evaluate the dependence of the seed passage speed of corn, winter wheat and oilseed rape on the air pressure in the supply hose from the fan to short vertical delivery tubes and to recommend appropriate settings of air pressure in the intake air to delivery tubes. Logarithmic function was chosen for the description of dependence of flyby speed of three crops seeds on air pressure in the vertical tubes. The speed of the seed at the end of seed tubes, established as necessary for high-speed seeding (10 m s-1) was achieved in all three test seed tubes when the air pressure in the supply pipe 3.0 kPa. Air speed in the vertical delivery tubes was 3.15 to 4.2 times higher than the speed of the seeds. Based on the correlation index values from 0.90 to 0.96, the high quality of the regression model was found in all cases. It was found that the short vertical delivery tubes of internal diameter 10, 12 and 14 mm are useful for a new developed seeder. On the other hand, deviations of seed passage speed for winter wheat seeds occur at higher air speed. Higher internal diameter of downtube decreased significantly seed passage speed for maize seeds.

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450–459 M. Krupička and A. Rybka
New design of roller separation line and its effect on the separation of hop matter
Abstract |
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New design of roller separation line and its effect on the separation of hop matter

M. Krupička* and A. Rybka

Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Agricultural Machines, Kamýcká 129, CZ165 21 Praha 9 - Suchdol, Czech Republic
*Correspondence: krupicka@tf.czu.cz

Abstract:

This article deals with the roller conveyor which constitutes a part of a machine line to separate the hops harvested from low trellises. Various parameters affecting the right operation of this roller conveyor are examined. In the last season a model of roller conveyor designed and constructed for this purpose was subject to experimental verification with the objective of integrating it in the actual line. Dependency of hop matter falling through on the gap size between rollers was examined. They were standard, commonly used rollers.
In 2015 rollers with a different diameter and different profile of metal welded collars were designed and produced. The new construction allows for reducing the gap between rollers up to 20 mm. As compared to the former solution including rollers of 60 mm in diameter, this one constitutes a difference of 28 mm.
The measurements in the season of 2015 were conducted using these new rollers and there were two parameters to examine. They were the gap size between rollers and rotation frequency of the rollers. The measurements were carried out using a hop matter sample taken from low trellises. The dependency of the hop matter falling through was being examined for 3 gaps (28, 24 and 20 mm) between rollers and for three rotation frequencies of the rollers. The measurements revealed that with a setting resulting in the smallest possible gap between rollers (20 mm) by up to 15% more leaves can be separated, compared to the rollers of 80 mm in diameter, and by approx. 60% more leaves compared to the former solution including the rollers of 60 mm in diameter. Furthermore it was found that a change in

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460–474 K. Kuimet, M. Järvis and A. Virovere
Integrating ergonomics principles and workplace health protection and promotion to improve safety and health at work – evidence from Estonia
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Integrating ergonomics principles and workplace health protection and promotion to improve safety and health at work – evidence from Estonia

K. Kuimet¹, M. Järvis²* and A. Virovere³

¹,³Estonian Entrepreneurship University of Applied Sciences, Suur-Sõjamäe 10a,
EE11415 Tallinn, Estonia
²Tallinn University of Technology, Ehitajate 5, EE19086 Tallinn, Estonia
*Correspondence: karin.kuimet@eek.ee

Abstract:

Previous scientific literature indicates that organisations manage workplace health promotion (WHP) in different ways. Despite conceptual and empirical justification, researchers have not consistently included concepts of WHP in ergonomics and safety studies.
The objective of the study is to explore workplace health protection and promotion activities available in Estonian organisations and to assess how ergonomic principles are integrated with workplace health protection and promotion within an  organisation.
The current study adopted a multi-method approach. The WHP activities were evaluated using the questionnaire of 36 items administrated to all members (organisations) of the Estonian Human Resource Management Association. A qualitative approach includes eight case studies (organisations, with the best practices of WHP and ergonomic interventions), semi-structured interviews with human resource personnel.
The data reveal key issues in WHP management in Estonian organisations. A statistical analysis of WHP questionnaires shows many organisations with outstanding programs and positive employers’ perceptions towards WHP. However, qualitative data indicate some important aspects of WHP and drawing attention to contextual variables in the development of safety management systems and improving the integration of ergonomics programs with WHP. The main contribution of the study is providing the conceptual clarification on incorporated WHP, how it complements a safety management system and showing its possible effect on employees’ health, safety behaviour and on knowledge exchange. It is essential for the established WHP program to have a fully integrated part of safety management system in the organisation and employees’ health and healthy behaviour must be recognised, acknowledged and be managed.

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475–484 A. Lazdinš, U. Prindulis, S. Kaleja, M. Daugaviete, and A. Zimelis
Productivity of Vimek 404 T5 harvester and Vimek 610 forwarder in early thinning
Abstract |
Full text PDF (341 kB)

Productivity of Vimek 404 T5 harvester and Vimek 610 forwarder in early thinning

A. Lazdinš¹*, U. Prindulis¹, S. Kaleja¹, M. Daugaviete¹,² and A. Zimelis¹

¹Latvian State forest Research Institute 'Silava', RPgas street 111, Salaspils, LV-2169,
Latvia
²Forest Sector Competence Center, DzRrbenes street 27, RPga, LV-1006, Latvia
*Correspondence: andis.lazdins@silava.lv

Abstract:

The scope of the study was to evaluate productivity of small size forest machines in early thinning, as well as to identify opportunities to use this technology to Latvia. The study was implemented in Sweden using Vimek 404 T5 harvester and Vimek 610 forwarder. The machines were driven by experienced operators; harvesting and forwarding methods were adopted to the operators’ experience. Time studies were done by team of researchers from Latvian State forest Research Institute ‘Silava’. The study demonstrated that Vimek 404 T5 harvester has considerable advantages in compare to conventional forest machinery to produce limited number of assortments like biofuel or mixture of pulpwood and biofuel in early thinning. Annual capacity of a single harvester working in one shift is 800 ha or 25,000 m3; however, application of the machine is limited – it might not work efficiently in commercial thinning in Latvia due to large number of assortments required by customers, and it has limited possibilities of utilization during seasonal restrictions of forest operations. Productivity of Vimek 610 forwarder is comparable with the conventional middle size forwarders; however it becomes less beneficial with increase of forwarding distance. Prime cost of biomass, including harvesting, forwarding and road transport to a 50 km distance is 14.3 EUR m-3. Hourly cost of Vimek 404 T5 and 610 is similar – 26–28 EUR h-1.

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485–494, J. Lev and M. Wohlmuthová
Segmented capacitance sensor and first tests of inverse problem solution
Abstract |

Segmented capacitance sensor and first tests of inverse problem solution

J. Lev¹* and M. Wohlmuthová²

¹Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Physics, Kamýcká 129, CZ 165 21 Prague 6, Czech Republic
²Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Mathematics, Kamýcká 129, CZ 16

Abstract:

 The segmented capacitance sensor (SCS) is developed for the purpose of material throughput measurement. SCS can be used in precise agriculture (e.g. yield maps creation) or for controlling of mass flow in stationary lines. This sensor is a compromise between simple capacitance throughput sensor which has been developed at the Department of Agricultural Machines Faculty of Engineering of Czech University of Life Sciences Prague and electrical capacitance tomography sensor. The SCS consists of the bottom plate (bottom electrode) and several upper electrodes which are placed parallel above the bottom plate. The upper electrodes are sometimes called segments of an upper plate. The bottom plate is undivided and it is assumed that it will be stored under measured material. During the measurement process the electric capacitance between one upper electrode and the bottom plate is measured every time. The sensor should be able to determine the distribution of material between upper electrodes and the bottom plate. This paper presents the algorithm of inverse problem solution. The algorithm was tested in two phases. The testing during the first phase was done via mathematical model which was presented in previous papers. Results show that the presented algorithm can be used for the inverse problem solution. For the purpose of the second testing phase a simple SCS was made. Electrical capacitances were measured by precise LCR meter. In the second testing phase, the inverse problem algorithm was tested using the actually measured data.

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495–512 Z. Libiete, A. Bardule and A. Lupikis
Long-term effect of spruce bark ash fertilization on soil properties and tree biomass increment in a mixed scots pine-Norway spruce stand on drained organic soil
Abstract |
Full text PDF (667 kB)

Long-term effect of spruce bark ash fertilization on soil properties and tree biomass increment in a mixed scots pine-Norway spruce stand on drained organic soil

Z. Libiete, A. Bardule and A. Lupikis*

Latvian State Forest Research Institute Silava, Rigas Str. 111, LV-2169 Salaspils, Latvia
*Correspondence: ainars.lupikis@silava.lv

Abstract:

Ash contains all plant nutrients, except N, and is often used to facilitate forest growth and to prevent nutrient depletion potentially caused by harvesting. In this paper, we report effects of a large dose of spruce bark ash on soil properties and tree biomass increment in a mixed Scots pine-Norway spruce stand on drained organic soil in central Latvia, 12 years after ash application. Significant positive growth response after wood ash fertilization was recorded only for overstorey spruce. During the 12 years after fertilization the additional volume increment was 8.3 m3 ha-1 or 0.7 m3 ha-1 annually. The effect of wood ash application is long-term. Also 12 years after treatment fertilized overstorey spruces demonstrated 0.6 m3 ha-1 additional annual volume increment compared to the controls. Additional diameter increment increased during the first 10 years after treatment but started to decrease in 2012. Results demonstrate that ash fertilization did not change N availability in the soil, and additional growth can be explained with improved supply of P, Ca, Mg and other nutrients. Ash application did not significantly influence the chemical composition of the O layer.

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513–524 C.M. Lind and L.M. Rose
Shifting to proactive risk management: Risk communication using the RAMP tool
Abstract |
Full text PDF (773 kB)

Shifting to proactive risk management: Risk communication using the RAMP tool

C.M. Lind* and L.M. Rose

KTH Royal Institute of Technology, School of Technology and Health, Unit of
Ergonomics, Alfred Nobels Allé 10, SE 141 52 Huddinge, Sweden
*Correspondence: cmeri@kth.se

Abstract:

Ergonomic risk factors are major contributors to work-related musculoskeletal disorders and quality deficiencies in the manufacturing industry. Due to lack of tools or systems that can support a systematic risk management of these production and health related factors, a new risk management tool (RAMP) was developed. In this paper, the risk communication system (the Results module) of this tool is presented along with a description of its development. An example of how it can be used, based on assessments performed in industry, is given. An evaluation of its usability, which included twenty practitioners active in the industry, gives support to the notion that the system is usable both for risk communication and as a decision base.

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525–532, J. Malaták, J. Bradna and J. Velebil
Combustion of briquettes from oversize fraction of compost from wood waste and other biomass residues
Abstract |
Full text PDF (265 kB)

Combustion of briquettes from oversize fraction of compost from wood waste and other biomass residues

J. Malaták*, J. Bradna and J. Velebil

Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Technological Equipment of Buildings, Kamýcká 129, CZ 165 21 Prague, Czech Republic
*Correspondence: malatak@tf.czu.cz

Abstract:

This article aims to determine experimentally the energy potential of samples from oversize compost fraction formed into briquettes. Theoretical combustion characteristics of the briquettes are determined and are compared with a reference fuel. Elemental analysis and stoichiometric calculations were performed for the samples. Classical grate combustion device with manual fuel supply was chosen for combustion tests. Flue gas temperature and emission parameters, such as the emission levels of carbon monoxide, carbon dioxide and nitrogen oxides, were monitored by a multi-purpose flue gas analyzer Madur GA-60. Dependence of these parameters on air input was followed.
Elemental analyses and stoichiometric calculations of individual samples indicate favourable properties of the energy compost for further energy utilisation, namely the gross calorific value of 16.42 MJ kg-1. Excess air was causing high losses through heat of the flue gas during the experiments on combustion device. This fact occurred in a situation when the temperature of flue gas leaving the chimney reached high levels. The excess air coefficient also significantly influenced emissions of carbon dioxide and monoxide and nitrogen oxides in the flue gas. The trends are analysed statistically and are expressed by regression equations. The results can serve in practice for optimization of combustion processes in grate boilers with manual feed of the fuel.

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533–539 H. Marušková and K. Pluhař
Quantitative research SME and STK in the Czech Republic
Abstract |
Full text PDF (231 kB)

Quantitative research SME and STK in the Czech Republic

H. Marušková* and K. Pluhař

Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Vehicles and Ground Transport, Kamýcká 129, CZ 165 21 Prague 6, Czech Republic
*Correspondence: maruskova@tf.czu.cz

Abstract:

The article deals with the emission control stations (SME) and technical inspection stations (STK) in the Czech Republic. The increasing number of vehicles and their operational age has significant impact on these stations. The nowadays situation in the both stations does not react adequately to the changing conditions. The use of quantitative research, which was conducted through an Internet poll in September 2015, obtained responses from SME and STK staff, as well as from the public. The questionnaire didn’t show substantial dissatisfaction with the current controls on SME and STK and there is no urgent need for immediate and major changes, but rather the need for continuous improvement and better control on SMEs, at least as at STK, i.e. the introduction of a central information database (preferably shared by STK and SME) and a camera system for better control. The cardinal question is not whether the existing emission checks on vehicles in no-load mode of the engines are able to detect all faults.

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540–546 M. Pexa, J. Čedík,, F. Kumhála and R. Pražan
Estimation of mulching energy intensity
Abstract |
Full text PDF (502 kB)

Estimation of mulching energy intensity

M. Pexa¹, J. Čedík,¹*, F. Kumhála² and R. Pražan³

¹Czech University of Life Sciences, Faculty of Engineering, Department for Quality and
Dependability of Machines, Kamycka 129, CZ 165 21 Prague 6, Czech Republic
²Czech University of Life Sciences, Faculty of Engineering, Department of Agricultural
Machines, Kamycka 129, CZ 165 21 Prague 6, Czech Republic
³Research Institute of Agricultural Engineering, p.r.i., Drnovská 507, CZ 161 01
Prague 6, Czech Republic
*Correspondence: cedikj@tf.czu.cz

Abstract:

Mulching is one of the energy-intensive activities in agriculture. The energy is gained from the consumed fuel. Besides the consumed fuel the combustion engine produces harmful and unharmful exhaust gases. The general trend is to reduce the production of harmful constituents of emissions as well as carbone dioxide. This can be achieved by various construction modifications or additional modifications of exhaust gases. It is possible to estimate the energy intensity in advance by several different ways. The paper presents the estimation based on measured complete characteristics of emissions production and the fuel consumption of used combustion engine and on the measured on-board data. The results show that the estimation of fuel consumption and thus also production of carbon dioxide can be relatively successful. The estimation differs quite significantly for other emissions components. During different transition modes of the combustion engine there is a change of emissions production which is hard to describe. The solution could lie in use of other parameters determining the operation mode of the engine in addition to the commonly used speed and torque of the combustion engine.

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547-555 M. Pexa, J. Čedík and R. Pražan
Smoke and NOX emissions of combustion engine using biofuels
Abstract |

Smoke and NOX emissions of combustion engine using biofuels

M. Pexa¹*, J. Čedík¹ and R. Pražan²

¹Czech University of Life Sciences, Faculty of Engineering, Department for Quality and Dependability of Machines, Kamycka 129, CZ 16521 Prague 6, Czech Republic
²Research Institute of Agricultural Engineering, p.r.i., Drnovská 507, CZ 16101 Prague 6, Czech Republic
*Correspondence: pexa@tf.czu.cz

Abstract:

Production of solid particles significantly increases the dangerousness of combustion engines. The excellent sorbtion characteristics of the solid particles increases their harmful effects and makes them very dangerous component of emissions which causes health problems. Currently there are many design solutions which aim to reduce smoke of combustion engines. One of the most significant solutions suggests increasing the injection pressures up to the limit of 250 MPa and filtering the exhaust gases. The paper compares different fuels and biofuels, whether used alone or in mixtures, and their effect on smoke of supercharged CI engine. The comparison uses the 8-point NRSC (Non-Road Steady Cycle) test during which the following fuels were used: diesel, rapeseed methyl ester, rapeseed oil, Jatropha curcas oil, biobutanol, hydrotreated oil and other blended fuels. The measurement and comparison results show that using biofuels can significantly reduce smoke of combustion engine by up to tens of percent in comparison to diesel.

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556–568 J. Prchalová, H. Čížková, R. Ševčík, K. Hanušová and A. Rajchl
Evaluation of shelf-life of fruit baby food
Abstract |
Full text PDF (354 kB)

Evaluation of shelf-life of fruit baby food

J. Prchalová, H. Čížková, R. Ševčík, K. Hanušová and A. Rajchl*

Department of Food Preservation, University of Chemistry and Technology Prague,
Technická 5, CZ 160 28 Prague 6, Czech Republic
*Correspondence: ales.rajchl@vscht.cz

Abstract:

Fruit baby food is an important food source in infant nutrition. This ambient stable product is processed using heat treatment and can be stored for one or more years at ambient temperature. An accelerated shelf-life storage test of fruit baby food was carried out. Sets of samples were stored at various storage temperatures (40, 55, 70 and 90 °C) for 3 weeks. Selected markers were followed and correlated with sensory evaluation during the storage. The markers were: DPPH, total phenols, ascorbic acid, 5-HMF, furfural and colour (expressed as L, a*, b* and nE). Kinetic data (reaction rate constants, activation energies, Q10, z values) were calculated. The aim of the paper was to evaluate shelf-lives of fruit baby food. The colour parameters, especially nE, seem to be a robust criterion which could be used to predict shelf-lives of fruit baby food.

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569–578 M. Raud, V. Rooni and T. Kikas
Explosive decompression pretreatment: nitrogen vs. compressed air
Abstract |
Full text PDF (243 kB)

Explosive decompression pretreatment: nitrogen vs. compressed air

M. Raud*, V. Rooni and T. Kikas

Institute of Technology, Estonian University of Life Sciences, Kreutzwaldi 56
EE51014 Tartu, Estonia
*Correspondence: merlin.raud@emu.ee

Abstract:

Lignocellulosic material is the most promising feedstock for the bioethanol production however, due to complicated physico-chemical characteristics of biomasses, it is necessary to pretreat the biomass before the bioethanol production. The goal of the pretreatment is to open the biomass structure for enzymatic hydrolysis to gain higher sugar and ethanol yields in further processes. In this paper a novel explosive decompression pretreatment is studied where two gases – nitrogen and compressed air are utilized for pressure generation. For this, traditional three-step bioethanol production process was used, where explosive decompression pretreatment with N2 gas or compressed air was applied for biomass pretreatment. Glucose and ethanol concentrations were measured during the process. Glucose and ethanol yields and process efficiencies were used to evaluate the effect of explosive decompression pretreatment and its suitability for biomass pretreatment in bioethanol production process. Results show that the highest glucose yield was gained when nitrogen gas was used, while difference in glucose yield compared to that of autohydrolysis was negligible when compressed air was applied.

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579–589 A. Zimelis, G. Spalva, G. Saule, M. Daugaviete, and A. Lazdinš
Productivity and cost of biofuel in ditch cleaning operations using tracked excavator based harvester
Abstract |
Full text PDF (276 kB)

Productivity and cost of biofuel in ditch cleaning operations using tracked excavator based harvester

A. Zimelis¹, G. Spalva¹, G. Saule¹, M. Daugaviete¹,² and A. Lazdinš¹*

¹Latvian State forest Research Institute 'Silava', RPgas street 111, LV-2169 Salaspils,
Latvia
²Forest Sector Competence Center, DzRrbenes street 27, LV-1006 RPga, Latvia
*Correspondence: andis.lazdins@silava.lv

Abstract:

Forest ditches is one of the poorly utilized sources of biomass for energy production and timber industry. Increase of productivity and reduction of cost of extraction of biomass from the ditches, retaining at the same time high quality standards, are the key issues of mechanization of harvesting operations in this area. The scope of the study was to evaluate productivity and cost of biomass delivered from forest ditches, when tracked excavator based harvester and different work methods are used. New Holland 215B excavator with Ponsse H7 felling head was used in trials. The machine was operated by experienced operators. The study was implemented in drainage systems managed by Joint stock company „Latvia state forests”. Total extracted area 12 ha, extracted biomass – 734 m3. Duration of the study including harvesting and forwarding – 4 months. Average cost of roundwood production including road transport to 50 km distance in the trials was 27 EUR m-3, average cost of biofuel – 11 EUR m-3 (4.5 EUR LV m-3). The study approved advantages of excavators in ditch cleaning operations; however, several improvements are possible. The machine should be equipped with smaller accumulating felling head, delimbing and bucking should be done in parallel to a ditch direction, number of assortments should be reduced, as well as extraction of trees with diameter below 6 cm should be avoided.

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590–603 H. Unal and H. Erdogan
Determination of the physical properties of different types of milk claws and air leaks in the claw according to rotameter-milk bucket methods
Abstract |

Determination of the physical properties of different types of milk claws and air leaks in the claw according to rotameter-milk bucket methods

H. Unal* and H. Erdogan

University of Uludag, Faculty of Agriculture, Department of Biosystems Engineering,
Bursa, Turkey; *Correspondence: hunal@uludag.edu.tr

Abstract:

In this study, physical properties (internal volumes, weight and the diameters of the hole in the milk and pulse tubes) of eighteen different types of milk claws which are one of the significant components of milking machine and the amount of air leaks in the claws were examined according to the flow meter (rotameter) and milk bucket experiment methods. ‘L’ type milking claw was 70 ml in volume which was lower than the standard minimum volume of 80 ml, however, others were higher. Five of the claws (‘C’, ‘D’, ‘E’, ‘H’ and ‘Q’ types of claws) were lower than 500 g, the minimum recommended standard for weight. Internal diameters of the short milk tube of the claws were between 5.5 and 10.8 mm. Internal diameters of all but one of the claws’ main milk output tubes (with a diameter of 11. 9 mm in ‘L’ type) were under the  minimum diameter (12.5 mm).
In experiments conducted with rotameter, the values of the leaking of the claw tap were between 0.0 and 11.0 l min-1. Air leakages of twelve claws (‘A’, ‘C’, ‘E’, ‘F’, ‘H’, ‘I’, ‘J’, ‘K’, ‘L’, ‘N’, ‘P’ and ‘R’ types of claws) were below the standard maximum level of 2 l min-1. The amounts of leaks in the tap of claws were between 0.0 and +14 l min-1. Ten milk claws in here (‘A’, ‘B’, ‘C’, ‘D’, ‘F’, ‘G’, ‘M’, ‘O’, ‘P’ and ‘R’ types of claws) did not meet the minimum and maximum flow rates. The total amounts of air leak in the claws in the experiments performed with a milk bucket were between 4.1 and 33.9 l min-1. Although the calculated amount of total air leak in all the claws was above the recommended minimum amount (4 l min-1), eight claws (‘B’, ‘C’, ‘D’, ‘E’, ‘H’, ‘J’, ‘K’, and ‘O’ types of claws) exceeded the maximum limit (12 l min-1).

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604–613 M. Uspenskaya, M. Kremenevskaya, K. Volkova and O. Sosnina
Aquaculture: problems and modern perspective on topical solution
Abstract |
Full text PDF (338 kB)

Aquaculture: problems and modern perspective on topical solution

M. Uspenskaya, M. Kremenevskaya, K. Volkova and O. Sosnina*

ITMO UNIVERSITY, Kronverksky pr. 49, RU 197101 St. Petersburg, Russia
*Correspondence: sosnina.olga.ITMO@yandex.ru

Abstract:

In this article describes the current problems of aquaculture. As a new material for feeding fish pond serves biocomposite based on protein hydrolysates and natural polymers. Also disclosed is a method of forming the proposed mother. Studies have been conducted biocomposite molecular weight and amino acid composition of the initial protein products.

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614–623 J. Velebil, J. Malalák and J. Bradna
Mass and energetic yields of hydrochar from brewer’s spent grain
Abstract |
Full text PDF (256 kB)

Mass and energetic yields of hydrochar from brewer’s spent grain

J. Velebil*, J. Malalák and J. Bradna

Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Technological Equipment of Buildings, Kamýcká 129, CZ 165 21 Prague, Czech Republic
*Correspondence: velebil@tf.czu.cz

Abstract:

 Brewer’s spent grain (BSG) was hydrothermally carbonized at combinations of three temperatures (180 °C, 215 °C, 250 °C) and three reaction times (2 h, 5 h, 12 h). For comparison, the corresponding barley malt was also tested at the same conditions. Elemental composition, volatile matter, ash and heating values were determined for original biomasses as well as resulting hydrochars. The mass yield of dry BSG hydrochar ranged from 45 to 73%. The energetic yield defined as retention of total lower heating value in the hydrochar on dry basis ranged from 66 to 85%. Specific lower heating value of dry material rose from 20.6 MJ kg-1 to 30.3 MJ kg-1 at the most severe conditions. Nitrogen and sulphur content in hydrochar were not strongly dependent on reaction conditions.

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624–634 K. Vennik,, P. Kukk, K. Krebstein and E. Reintam
The relationship between precompression stress and rut depth of different soil types in Estonia
Abstract |

The relationship between precompression stress and rut depth of different soil types in Estonia

K. Vennik¹,²*, P. Kukk², K. Krebstein² and E. Reintam¹

¹Dept. of Soil Science and Agrochemistry, Institute of Agricultural and Environmental
Sciences, Estonian University of Soil Sciences, Kreutzwaldi 1a, EE 51014 Tartu, Estonia
²The Estonian National Defence College, Riia 12, EE 51013 Tartu, Estonia
*Correspondence: kersti.vennik@mil.ee

Abstract:

In agriculture as well for other purposes off-road vehicles have to move cross-country. Precompression stress is used to describe the load bearing capacity of different soils. The aim of the study is to investigate the relationship between precompression stress and rut depth for different Estonian soil types after 1 and 10 passes of a vehicle. Traffic experiments were conducted at eight experiment sites throughout Estonia using a 7 t truck and a 23 t wheeled vehicle. The experiment sites were selected based on the Estonian soil map. Rut depth was measured after the first pass and ten passes. Undisturbed soil samples were collected from topsoil and from subsoil right next to the track. Soil samples were compressed in an oedometer at stresses of 25, 50, 100, 200, 400 and 600 kPa. The Casagrande procedure was used to determine the precompression stresses. In topsoil, if the moisture content of a soil is high, then the differences in the precompression stress values of the various soil types disappears while in the subsoil layer the precompression stress is more dependent on the soil properties. The precompression stress cannot by itself be used as a threshold value to determine small and large sinkage. The choice of fitting methods for composing of stress compaction curve is critical and led to the preference of the logistic curve. The values of logistic functions at the points of their maximal curvature and calculation based on the area on stress-compaction graph can be used for prediction of rut depths.

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