2018, Vol. 16, No. 2

Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/5375

Sirvi

Nüüd näidatakse 1 - 20 30

The excretion of Ca, Mg, Zn and Cu via excreta of laying hens fed low phosphorus diets and phytase
(2018) Kamberi, M.A.; Muji, S.; Kryeziu, A.; Kastrati, R.; Mestani, N.
An 8 – week experiment was conducted to study the effect of adding phytase (Natuphos ® 5000 BASF) to low and normal available phosph orus diets of laying hens on the excreta content and excretion of Ca, Mg, Zn and Cu. A total of 144 Hisex Brown laying hens that were 22 weeks old at the start of the experiment were randomly assigned to four dietary treatments. Treatments included three r eplicates (12 hens each) or 36 hens per treatment in total. Four corn - soybean meal - based diets were formulated to contain two levels of available phosphorus (AP; 0.12 and 0.46%) and two phytase levels (0 and 600 FTU kg – 1 ). The results showed that there was no significant effect of added phytase on excreta Ca and Mg content ( P > 0.05), but there was a significant effect of the dietary treatment on the content of Zn ( P = 0.0075) and Cu ( P = 0.0002). In terms of the excretion of these mine rals, the dietary treatment had no effect on Ca and Zn excretion and a borderline effect ( P = 0.0522) on Mg excretion measured as the amount of the mineral excreted per egg mass produced is observed. The results however showed a very strong effect of all three factors (available phosphorus, phytase and their interaction) on Cu excretion. The r esults indicate that adding 600 FTU to the corn - soybean meal laying hen diet with 0.12% or 0.46% AP beneficially affects the content and the excretion of Ca, Mg, Zn and Cu. Therefore, we can conclude that a laying hen diet containing 0.12% available phosphorus and 600 FTU during the first production cycle may not only satisfactorily support hens’ perf ormance but will also beneficially affect the environment.
Effect of nitrogen fertilization on winter wheat yield and yield quality
(2018) Litke, L.; Gaile, Z.; Ruža, A.
Wheat ( Triticum aestivum L.) is the most common cereal, which is grown in Latvia. Nowadays, farmers are trying to get high grain yields in line with food quality, at the same time trying to minimize production cos ts and to use environmentally friendly technologies. The objective of this experiment was to clarify the impact of nitrogen fertilization on winter wheat yield and yield quality under two soil tillage systems and after two forecrops. Trials were conducted at the Research and Study farm ‘Peterlauki’ of Latvia University of Agriculture (56 ° 30.658 ’ N and 23 ° 41.580 ’ E). Researched factors were (1) crop rotation (wheat/wheat and oilseed rape ( Brassica napus ssp. oleifera )/wheat), (2) soil tillage (traditional soil tillage with mould - board ploughing at a depth of 22 – 24 cm and reduced soil tillage with disc harrowing at a depth below 10 cm ), (3) nitrogen fertilizer rate (altogether eight rates: N0 or control, N60, N90, N120(90+30), N15 0 (90+60) , N180 (90+60+30) , N210 (90+70+50) , and N240 (120+60+60)), and (4) conditions of the growing seasons 2014/2015, 2015/2016 and 2016/2017. The results indicate that winter wheat yield has been significantly affected by soil tillage, nitrogen fertilizer rate ( p < 0.001) and forecrop ( p < 0.05). Three - year research confirmed significant yield increase until the nitrogen fertilizer rate N180. Significantly higher average grain yield was obtained under traditional soil tillage. Nitrogen fertilizer affected significantly all tested yield quality indicators ( p < 0.001) . Increase of nitrogen fertilizer rate secured significant increase of winter wheat grain quality indices, except starch content, after both forecrops and in both soil tillage variants. Values of yield quality indicators increased significantly enhancing N - rate from N150 up to N 210.
Influence of inoculation and phosphorus regimes on symbiotic nitrogen fixation and phosphorus use efficiency of Algerian cowpea (Vigna unguiculata L. (Walp.)) landraces
(2018) Benlahrech, S.; Kac, G.; Teffahi, M.; Ounane, S.M.
To study the genotypic variation of cowpeas on plant growth and phosphorus (P) uptake which is a function of different P regimes in the soil rhizosphere , 6 landraces of cowpea commonly found in northern Algeria ( NE4, NE10, NE11, NKT5, NKT7, NKB7 ) and 4 landraces from Sahara in southern Algeria (NAG4, NAG5, NAT2 and ND3) were studied during 2013 – 2014 in greenhouse. They were inoculated with Mesorhizobium sp. (S1), Bradyrhizobium sp. (S2) and co – inoculation (S1 – S2) under three P treatments: no P supply (P0), soluble P (PP) and insoluble P (TCP). Only varieties commonly found in northern Algeria nodulated with soluble P (PP) and inoculation containing Mesorhizobium sp . (S1). As a result of the symbiosis, the use of S1 has significantly increased shoot dry weight by 22%, total P content by 20% and P use efficiency for symbiotic nitrogen fixation by 18% compared to no inoculation (T). The landraces from the northern of Algeria expressed a higher growth than those from Sahara in the south of Algeria, especially three of them (NE4, NE10 and NE11) who showed a high performance under all P regimes. We suggest that these three landraces may be useful for improving symbiotic nitrogen fixation in cowpeas when growth is limited by low – P soils and that they could contribute to sustainable farming systems through reduction of farm er’s dependence on fertilizers.
Research on the mineral composition of cultivated and wild blueberries and cranberries
(2018) Karlsons, A.; Osvalde, A.; Čekstere, G.; Pormale, J.
European cranberry ( Vaccinium oxycoccos L.) and European bilberry ( Vaccinium myrtillus L.) are among the most popular wild - harvested fruits in Latvia, traditionally used in folk - medicine and food. The commercial cultivation of American cranberry ( Vaccinium macrocarpon Ait.) and highbush blueber ry ( Vaccinium corymbosum L.) was successfully started during last 20 years. With a berry production increase due to considerable hectarage of plantings and growing consumer interest in health - improving foods cultivated blueberries and cranberries have foun d a place in a daily intake as an excellent source of phenolic and nutritive compounds, vitamins and minerals. As the chemical composition of Vaccinium spp . has an important implication on human health, detailed information on the nutritional content of berries are of special importance. The aim of this study was to compare the contents of twelve biologically essential elements (N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, Mo, B) in b erries of four Vaccinium species: cultivated and wild blueberries ( Vaccinium corymbosum and Vaccinium myrtillus ) and cranberries ( Vaccinium macrocarpon and Vaccinium oxycoccus ). Together 136 (leaf and berry) samples were collected from 7 main cranberry and blueberry producing sites and 17 native woodland areas and bogs in Latvia. A comparison of wild and cultivated species showed similar concentrations for the macroelements K, Ca and S in cranberry and N, P in blueberry fruits. While statistically significa nt differences were found for N, P and Mg in case of cranberries and Ca, K, Mg and S for blueberries. The research revealed statistically significant differences of most micronutrients in cultivated and wild berries. Plant leaf and fruit analysis revealed the organ - specific distribution of mineral elements in all species studied. In most of the cases, leaf analysis supported concentration differences in fruits.
The indigenous arbuscular mycorrhizal fungal colonisation potential in potato roots is affected by agricultural treatments
(2018) Loit, Kaire; Soonvald, Liina; Kukk, M.; Astover, Alar; Runno-Paurson, Eve; Kaart, Tanel; Öpik, Maarja; Estonian University of Life Sciences. Chair of Plant Health; Estonian University of Life Sciences. Chair of Soil Science; Estonian University of Life Sciences. Chair of Crop Science and Plant Biology; Estonian University of Life Sciences. Chair of Animal Breeding and Biotechnology
There is an urgent need to develop novel approaches to enhance sustainable agriculture while not reducing cr op yields. Arbuscular mycorrhizal (AM) fungi establish symbiotic associations with most crop plants improving plant performance and soil health. This study investigated the extent of colonisation of potato roots by indigenous AM fungi in the arable soil under conventional and organic farming systems. Potato roots had greater AM fungal colonisation levels under organic than conventional farming, though in general, root colonisation levels were extremely low in both farming systems . Pota to root AM fungal colonisation was lower with higher soil P content and higher with higher annual C input. Trap plant root AM fungal colonisation was considerably higher than in field potato roots and showed that soil mycorrhizal inoculum potential was hig her in organic than in conventional farming. Thus, the positive impact of manure application in organic fields to the potato AM fungal colonisation can be explained by previous higher total annual C fresh organic matter input and lower soil P content under treatment. Furthermore, the natural AM fungal abundance in the soil was sufficient to colonise trap plant roots, suggesting a low mycorrhizal dependence of the studied potato cultivar.
Productive performance of broilers at the final stage of breeding submitted to different levels of metabolizable energy in different thermal environments
(2018) Oliveira, K.P.; Ferreira, C.F.S.; Tinoco, I.F.F.; Andrade, R.R.; Barbari, M.; Cruz, V.M.F.; Baptista, F.J.F.; Vieira, M.F.A.; Conti, L.; Rossi, G.
The Brazilian poultry industry is an activity in constant development due to the high indices of productive efficiency. The accelerated evolution of poultry production has allowed to obtain early and very efficient broilers able to convert different foods into animal protein. However, due to this intensive breeding system, a series of metabolic and management problems appeared, with emphasis on thermal stress. The objective of this work was to evaluate the physiological responses of broiler chickens in the final stage of breeding (21 to 42 days of life), submitted to two thermal conditions, one representative of the thermoneutrality situation (T1) and one giving a situation of cyclic stress by heat (T2). For each experimental thermal condition, the birds were submitted to different levels of metabolizable energy of 3,050, 3,125, 3,200, 3,275 kcal kg - 1 . At 28, 35 and 42 days, the birds and the feed leftovers were weighed to measure the performance variables: CR (feed intake), GP (weight gain) and CA (feed conversion), viability of the rearing (Vb), productive efficiency index (PEI). As conclusions, the GP was 13.6% higher for the birds maintained at the thermoneutrality situation T1. Th e PEI was 32.5% higher for the birds maintained in T1 condition, when compared to those kept in T2. However, both in thermoneutral and in heat stress conditions, the increase in the level of metabolizable energy in the diet did not influence the performanc e and the productive efficiency index of broiler chickens aged between 21 and 42 days of age.
Energy potential of densified biomass from maize straw in form of pellets and briquettes
(2018) Križan, M.; Krištof, K.; Angelovič, M.; Jobbágy, J.; Urbanovičová, O.
The aim of the study was the evaluation and comparison of energy potential of briquettes and pellets produced from the maize straw and woody biomass based on various diameters of pellets. By experimental measurements a calorific value and ash content was obser ved. Calorific value was measured by laboratory calorimeter IKA C 6000 (IKA® Works, Inc., USA) and laboratory combustion chamber Lindberg/Blue M (Thermo Fisher Scientific, Inc., USA). Individual calorific values and ash content was observed and subsequentl y confronted to obtain differences with replication. The analysis showed that calorific value of pellets with diameter 6 mm ranged from 16.99 MJ kg - 1 to 17.80 MJ kg - 1 . Calorific value of pellets with 8 mm diameter ranged from 16.63 MJ kg - 1 to 17.20 MJ kg - 1 . However, compared calorific value of briquettes ranged from 14.99 MJ kg - 1 to 15.66 MJ kg - 1 . Further analysis showed that ash content of samples varied as well and it’s even affected by diameter of pellets. While ash content of pellets with diameter 6 mm was observed as 4.9% of total volume in case of pellets with 8 mm it was observed at value 5.5%. Briquettes produced from maize straw have ash content at value 5.4%. In contrary, ash content of woody biomass was significantly higher, 11% of volume, specifi cally. At the basis of observed parameters it can be concluded that maize straw densified in form of briquettes and pellets have a great energy potential which is comparable and competitive with currently used materials for production of briquettes and pel lets.
Evaluation of break-even point and gross margin economic risks in producing winter oilseed rape
(2018) Mimra, M.; Kavka, M.; Markytán, P.
The economic result of growing winter oilseed rape is influenced by a number of variables, such as natural influences, input prices and the used technology. One of the ways to improve the business’s prof itability is to use the experience and knowledge provided by consulting companies. This paper analyses two data series covering the period of 5 to 10 years regarding specific selected key parameters for companies using the counselling services of the Union of Oilseeds Growers and Processors in Prague (UOGP) and some other companies that make no use of these services (OTHERS). For the selected key parameters, the risk analysis of reaching the gross margin and the break - even point was conducted with the aid of the Monte Carlo stochastic simulation method. The results of the calculations show that the companies using UOGP consulting achieve on average, at the same level of risk, a gross margin higher by 30% and their break - even point is lower by 11%. Taking adv antage of the knowledge and services provided by a consulting company has positive economic benefits, and it increases the competitiveness of companies.
The role of field beans in nutrition of Boer goat
(2018) Aplocina, E.
A study on the effective using of field beans to Boer mother goats feeding was carried out on a farm whose main activity is the production of goat meat. Since the Boer goat breed is still very rare in Latvia, there is a lack of experience in the feeding of meat goat. Goat productivity was analyzed according to the birth weight of goat kids a nd kids live weight at 50 days, as well as the average live weight gain of kids per day up to 50 days old. For control group goats a relatively high energy shortage (14% of the daily requirement) and protein deficiency (29% of the daily requirement) were o bserved in feed ratio. Adding fodder beans and maize into the feed, it is possible to optimize feed ratio for energy and protein supply. Experimental activities had shown that by the inclusion of field beans and maize in feed ratio of goat's mothers, the a verage increase in live weight of kids up to 50 days old was by 58.2% higher (P < 0.05) than that of kids in which goats' mothers received only oats as concentrated feed. By the optimization of feed ratio, it is possible to achieve a higher milk productivity of goat mothers and hence larger live weight gain for kids, which reduces the feed c osts by up to 9% for 1kg of live weight. By optimizing the breeding and feeding of mother goats and kids, it is possible to achieve greater animal fast - growing, hence, more efficient and cost - effective management.
The European performance indicators of broiler chickens as influenced by stocking density and sex
(2018) Kryeziu, A. J.; Mestani, N.; Berisha, Sh.; Kamberi, M. A.
The aim of this study was to investigate the influence of different stocking densities on the growth performance of Ross 308 broiler chickens up to six weeks of age. A to tal of 216 one - day broiler chicks were randomly assigned to three treatment groups based on the stocking density: Low (LSD) = 14 chickens m - 2 , Medium (MSD) = 18 chickens per m 2 and High (HSD) = 22 chickens m - 2 , with four replications. Higher body weight gain (TWG) was observed for the low (2,043.89 g) and medium (2 , 008.03 g) compared to the high (1,901.51 g) density. The study revealed that chickens of the LSD treatment consumed significantly ( P < 0.01) more fe ed compared to the HSD chickens. High stocking density (22 m - 2 ) tended to improve feed conversion ratio compared to medium (18 m - 2 ) and low (14 m - 2 ) stocking density, but the differences were not significant ( P > 0.05). From the results of this study it can be concluded that broiler chicks can be stocked up to 22 chickens m 2 , as far as required standards are assured.
Comparison of two sowing systems for CTF using commercially available machinery
(2018) Macák, M.; Rataj, V.; Barát, M.; Galambošová, J.
The crop establishment belongs to crucial technology operations. The quality of sowing is the basis for obtaining efficiency of production. Controlled Traffic Farming (CTF) is a technology which prevents excessive soil compaction and minimizes compacted area to the smallest possible area of perman ent traffic lanes (PTL). There were two sowing systems compared, namely row and band sowing when growing winter barley. Sowing parameters as well as all other field operations were identical for both compared systems. Measurements were conducted at an expe rimental field on non - compacted and traffic lane areas where CTF system was introduced in 2009, with 64% of compacted and 36% of non - compacted soil. Six crop parameters were analysed. Generally, it can be concluded that the band sowing performed better in yield (by 9.3% in non - compacted area; by 3.8 % in traffic lane), ear number (by 5.2% in non - compacted area; by 10.1% in traffic lane) and grain number (by 6.3% in non - compacted area; by 8.1% in traffic lane) as well as crop height (by 6.6% in non - compacted area; and by 2.4% in traffic lane). The only parameter performing worse was TGW with decrease of 6.6% in non - compacted area and decrease 2.8% in traffic lane for band system. Differences in number of grain per ear were negligible.
Differential thermal regulation of the growth of the bee colonies in the early spring period
(2018) Jehlička, T.; Sander, J.
This paper addresses the issue of the control of activity and growth of the bee colonies (brooding) in the early spring period. The bees are brooding up already in the late winter, and the intensity of brooding in this period is determined by daytime tempe ratures and sunshine hours that increase the temperature of the inner hive space. The objective is to design and verify a technology that would ensure the conditions for the optimal brooding in the early spring period and thus the numerically strong bee co lonies. The experimental part was based on the temperature regulation in the inner hive space. A preset temperature was maintained inside the hive by an electric heating system with regulation. A differential thermal regulation which enabled the optimal gr owth of the bee colonies in accordance with the phenophases was chosen for verification. To verify the proposed method, two groups of the bee colonies were assembled. One group of the bee colonies had a heating system with regulation installed inside the h ive. The second group of the bee colonies was in the hives without the heating system installed. The dependence of the brood area on time was monitored for the evaluation of both groups of the bee colonies. It was proven that the differential thermal regul ation enables the optimal growth of the bee colonies in the early spring period in accordance with the phenophases. The brood area increased evenly for the group of the bee colonies with a regulated temperature of the hive space, reaching a larger area.
Low temperature BMP tests using fish waste from invasive Round goby of the Baltic Sea
(2018) Gruduls, A.; Balina, K.; Ivanovs, K.; Romagnoli, F.
Round goby (Neogobius melanostomus ) is an invasive fish species in the Baltic Sea. While meat can be used for human consumption, fish processing residues are considered as a waste. Within circular economy and bio - economy perspectives fish waste could be used as a valuable feedstock for biogas prod uction. However, the research is mostly focused on evaluating biogas yield at mesophilic conditions (i.e. 37 °C ). In this study the impact of low temperature on Biochemical Methane Potential (BMP) tests has been investigated. Round goby’s processing leftov ers - heads, intestines and skin/bone mixture were tested in codigestion with sewage sludge. Anaerobic digestion (AD) was carried out in 100 mL batch tests at low temperature 23 °C and 37 °C conditions, over an incubation period of 31 days. The results sho w that AD at low temperature occurs twice as slowly as under 37 °C conditions. However, after 31 days the BMP values for 23 °C samples were only 2% lower than for high temperature samples. Heads and skins showed similar BMP values reaching on average 502 L CH 4 kg VS - 1 and 556 L CH 4 kg VS - 1 respectively. BMP for fish intestines was higher, reaching on average 870 L CH 4 kg VS - 1 . Average BMP for mixes of fish heads, skins, intestines and bones was 660 L CH 4 kg VS - 1 . Acquired BMPs were further compared with the theoretical BMPs from Buswell's formula. Research results suggests that anaerobic digestion of fish waste under low temperature conditions could be feasible as the process still efficiently occurs, in fact ope ning a new opportunity to explore the overall sustainability of technologies based on these conversion processes.
Combustible in selected biofuels
(2018) Vitázek, I.; Tulík, J.; Klúčik, J.
The aim of the research was to determine the moisture, combustible and ash content in selected biofuels, in dependence on temperature by the means of gravimetric method. For this purpose, the furnace Nabertherm L9/11/SW/P330 was used. Analyzed samples cons isted of crushed biomass which is used in small heat sources (e.g. spruce wood, cherry wood, apple wood, black locust wood) with bark and without additives. Biomass for larger heat sources (woodchips cuttings from coniferous trees), sawdust mix (plum, cher ry, walnut, apricot, apple) and pellets (90% spruce and 10% fir) were also analyzed. The results are processed graphically and enable to characterize the tested fuels. The highest content of combustible was found in spruce wood sample without bark (99.889% ), the lowest content of combustible indicated cuttings from coniferous trees (88.402%). Gravimetric experiments were supplemented by DSC measurement of selected samples on calorimeter Toledo DSC822e. The graphic courses of reactions are provided up to 500 °C.
Solution for remote real-time visual expertise of agricultural objects
(2018) Komasilovs, V.; Zacepins, A.; Kviesis, A.; Nasirahmadi, A.; Sturm, B.
In recent years automated image and video analyses of plants and animals have become important techniques in Pre cision Agriculture for the detection of anomalies in development. Unlikely, machine learning (i.e., artificial neural networks, support vector machine, and other relevant techniques) are not always able to support decision making. Nevertheless, experts can use these techniques for developing more precise solutions and analysis approaches. It is labour - intensive and time - consuming for the experts to continuously visit the production sites to make direct on - site observations. Therefore, videos from the site n eed to be made available for remote viewing and analysis. In some cases it is also essential to monitor different parts of objects in agriculture and animal farming (e.g., bottom of the plants, stomach of the animal, etc.) which are difficult to access in standard recording procedures. One possible solution for the farmer is the use of a portable camera with real - streaming option r ather than a stationary camera. The aim of this paper is the proposition of a solution for real - time video streaming of agricultural objects (plants and/or animals) for remote expert evaluation and diagnosis. The proposed system is based on a Raspberry Pi 3, which is used to transfer the video from the attached camera to the YouTube streaming service. Users will be able to watch the video stream from the YouTube service on any device that has a web browser. Several cameras (USB, and Raspberry Pi camera) and video resolutions (from 480p till 1 , 080p) are compared and analysed, to find the best option, taking into account video quality, frame rates, and latency. Energy consumption of the whole system is evaluated and for the chosen solution it is 645 mA.
Evaluation of the mechanized harvest of grapes with regards to harvest losses and economical aspects
(2018) Jobbágy, J.; Krištof, K.; Schmidt, A.; Križan, M.; Urbanovičová, O.
The aim of the study was to evaluate the mechanized grape harvest conducted by the trailed harvester. As a criterions was introduced the performance, harvest losses of grapes and economic efficiency from the perspective of its introduction. The calculatio ns consist of total annual and partial unit costs also with regards to indirect costs which are formed by the grape losses during the harvest. Evaluation was conducted on three varieties of grapes. The losses of grapes, total annual and partial unit costs were calculated for selected varieties of grapes and also for whole production area. The mean grape losses for whole production area were determined at 470 kg ha - 1 , while the greatest portion of these losses (9.7%) was observed in case of Neronet variety. Among other analysed aspect were the efficiency of mechanized harvest introduction by definition of labour costs and the ransom price of grapes in relation with minimum required area. A substantial part of total costs for area 100 ha was formed by direct c osts up to 15.24% greater than the indirect costs. The efficiency of machinery introduction into the harvest process was observed at minimum area of 16.92 ha in case of rental mechanized harvest of grapes. In case of mechanized harvest conducted by previou sly bought trailed grape harvester the value of minimal efficiency was determined at 27.42 ha year - 1 . As a result then serves an effective utilization of mechanized grape harvest in selected company but it is not limited to it and can be applied on any oth er scenario.
Management of Brazilian hardwood species (Jatoba and Garapa) wood waste biomass utilization for energy production purposes
(2018) Chiteculo, V.; Brunerová, A.; Surový, P.; Brožek, M.
In the Federative Republic of Brazil, Jatoba ( Hymenaea courbaril ) and Garapa ( Apuleia leiocarpa ) trees are intensively harvested . The yield of one log is approximately 45 – 55%, which indicates a great amount of produced wood waste biomass.Present research monitored the suitability of wood waste biomass from Jatoba and Garapa trees for bio – briquette for solid biofuel production. The research was focused on chemical parameters, and energ y potential of such biomass kinds. Jatoba wood waste biomass was used for the production of bio – briquette fuel and its final mechanical quality was investigated by determination of their mechanical quality indicators. Results of chemical analysis (in wet b asis) exhibited great level of ash content in case of both species ( Jatoba – 0.31%, Garapa – 3.02%), as well as high level of energy potential; net calorific value equal to 18.92 MJ kg – 1 for Jatoba and to 18.39 5 MJ kg – 1 for Garapa. Analysis of elementary composition proved following levels of oxygen content: J atoba – 41.10%, Garapa – 39.97 %. Mechanical analysis proved bio – briquette samples volume density ρ equal to 896.34 kg m – 3 which indicated quality bio – briquette fuel , while the level of rupture force R F occurred at a lower level – 47.05 N mm – 1 . Most important quality indicator, the mechanical durability DU, unfortunately, occurred at a lower level; DU = 77.6% compared to the minimal level of bio – briquette fuels intended for commercial sales which must be > 90%. Overall analysis proved materials suitability for energy generation purpose with certain limitations which can improve by changing production parameters of briquetting.
Chemical composition of agromass ash and its influence on ash melting characteristics
(2018) Čepauskienė, D.; Pedišius, N.; Milčius, D.
The increasing demand for biofuels leads to a growing need for agromass, such as herbaceous plants and agricultural waste. However, agromass contains high quanitites of alkali metals, mainly potassium and sodium, which limits agromass usage in thermoconversion processes. Alkali metals react with other ash forming elements which leads to ash related problems such as agglomeration, fouling and slagging during agromass burning. In this study, chemical composition and melting behaviour of ashes form ed at 550 ° C are investigated. Three herbaceous plants (reed canary grass, hemp, orchard grass), four types of agricultural waste (straws of rye, wheat, buckwheat and canola) and two types of woody biomass (birch, spruce) are selected. Ash melting behaviou r, composition and bulk structure are determined using a high temperature furnace with a video camera, inductively coupled plasma atomic emission – spectrometry and X – ray diffraction technique, respectively . Ash melting behaviour of selected agromass types s hows that the hemp ash has the highest shrinkage starting temperature which reaches 1 , 079 °C. This is due to the high content of calcium and low content of potassium and sodium in hemp ash. T hree main components calcium carbonate, potassium sulfate and pot assium chloride have been identified in ashes after agromass and woody biomass are heat – treated at temperature of 550 °C.
Red clover drying coefficient dependences on air velocity at constant drying temperature
(2018) Aboltins, A.; Tomsu, J.; Kic, P.
The clover is widely used as feed of animals and preservation of fodder is an important problem. This paper informs about the experimental and theoretical investigations of red clover ( Trifolium pratense ) drying by force d convection. This research is focused on verification of influence of different air velocities on the drying process of red clover in thin layer in mild temperatures (22 °C ) and rather high relative humidity of air (70 % ). The initial moisture content of clover was determined by gravimetric method using the hot air drying in the electric oven. Special device for convection drying with air flow passing through material from the bottom through supporting trays with a sieve (dimensions of mesh 3 x 4 mm) by co nstant temperature was used for drying when the air velocity 0.7 m s - 1 , 1.0 m s - 1 , 1.2 m s - 1 and 2.0 m s - 1 . These results was compared with drying by free convection. Changes of clover samples were determined from the measured values of weight using the gr avimetric method. The function of drying coefficient K(t) is determined (using thin layer theory) and theoretical results are compared with experimental results. Using experimental results were determined relationships between air velocity and parameters i ncluded in function of drying coefficient. This allows theoretically to predict the drying process depending on the air velocity.
Intensification of rapeseed drying process through the use of infrared emitters
(2018) Bulgakov, V.; Bandura, V.; Arak, Margus; Olt, Jüri; Estonian University of Life Science
The theoretical basis of the agricultural material drying techniques has been formed in the world for two and a half centuries. Nevertheless, despite the multitude of studies well presented in the literature, the i ndustry still lacks universally recognized methods of design calculation for the majority of drying problems. Presumably, this is due to the fact that the dehydration of foodstuffs is one of the most energy - intensive and complicated work processes. In the process of thermal treatment during the drying, the physical state of the water in the treated item changes, the properties of the item itself are altered. Recently, the drying of foodstuffs by means of infrared (IR) radiation has been gaining ever wider a cceptance. At the same time, the technologies for dehydrating foodstuffs and materials are now far ahead of the theory of drying. Not only the classical literature on the drying problems, but even special studies on the subject cannot provide any specific recommendations for the design of installations with the electro - magnetic principle of energy input. Whereas that is exactly the type of installations that are now actively making headway, while offering serious challenges in their modelling. For that reas on, experimenting has until now been the only reliable way of their studying. Despite the available extensive scientific literature on the drying, including works on IR units, the practical issues of engineering IR driers have not been tackled. All the exi sting studies consider solely particular cases. This study discusses the process of drying the fixed bed of rapeseeds with the use of the electromagnetic infrared emitter. The energy intensity of the process and the optimum thickness of the product bed are determined. The aim of the paper is to examine the effect that the operating condition parameter s (energy input intensity, temperature, grain bed thickness) have on the drying kinetics and the energy characteristics of the process. The methods of research are based on the thermophysical analysis of the material’s structure. The experimental studies were carried out with the use of monitoring and measuring equipment, up - to - date methods and instruments, including solutions developed by the authors. The analy tical treatment was performed with the use of the software packages: MathCAD, Excel. The sample testing and examination took place in the laboratory and the methods were in compliance with the applicable standards. A comprehensive experimental investigatio n of the effect that the operating parameter s (specific load and power) have on the rape seed IR - drying kinetics had been accomplished.

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