Abstract. Odour from agriculture causes local nuisance to the neighborhood. Litter and cover materials can be used in animal housing and in storage of manure to reduce the odour problem. The use of biochar as a covering for animal manures is a new innovation and enhances the possibility to minimize the emissions from animal farms. (Research purpose) To study the possibility of using a mixture of biochar and peat as a manure covering, in order to reduce the intensity of odor on livestock farms. (Materials and methods) The potential of a mixture of biochar and peat for the odour control was tested in a laboratory study. A 10 cm layer of fresh mink manure was placed on the bottom of a 5 liter test bucket and the manure was covered with biochar-peat mixture (mixed in 50/50 ratio by volume) using five different covering thicknesses. Uncovered manure was used as a reference. The odour emission was measured with an olfactometric method that is based on odour sensation of a person. Also the character of the odour was described. (Results and discussion) The results show that a biochar-peat covering of at least 3 cm is able to considerably reduce the odour from the manure. The character of the odour was at first peat-like for all covered buckets but with thin coverings it was changed to more manure-like after 2 days. The odour from buckets with thicker covers remained peat-like during the whole testing period. (Conclusion) It is recommended to apply a biochar-peat covering to neutralize ammonia and the unpleasant manure odour on livestock farms. The author has shown that the frequency of use and the thickness of a covering layer depend on the ambient temperature; therefore, it is not necessary to cover manure in winter.

Abstract. The soil surface balance of nitrogen (N), calculated as the difference between N inputs and output, is a principal agri-environmental indicator that provides information on the potential loss of N to surface or groundwater. (Research purpose) Determination of relevant models of yield response to N fertilization could prove helpful in minimizing N balance and simultaneously maintaining high-yield production. (Materials and methods) The authors used meta-analysis to quantitatively summarize 40 N fertilization experiments on perennial grass leys in Finland and assessed the effect of inorganic N fertilization on grass yields and N balances, and further estimated potential to reduce N input and N balances. The relationship was estimated by using the COUP model (a coupled heat and mass transfer model for ‘soilplant-atmosphere’ systems) and by reviewing the 12 Nordic studies on N leaching experiments involving lysimeters and drained field plots. (Results and discussion) It was found that the optimal N content in mineral soils is 230 kilograms per hectare, in organic – 190. In the first case, the economic effect of nitrogen introduction is 206 euro per hectare, in the second one – 62. (Conclusions) The developed yield response models can serve to construct a dynamic tool for growers to adjust N applications for maximizing economic profitability. The authors proved that the values predicted by the COUP model for N leaching losses after the application of mineral N fertilizer to perennial grass leys were in accordance with the low values measured, which ranged from 1.2 to 10-15 kilograms per hectar a year in Finland and in the Nordic-Baltic countries. It was also revealed that a possible risk of N leaching losses when using only inorganic N fertilization seems less crucial due to its low level and weak association with N balances.

Abstract. Intensified production, an increased fleet of vehicles with internal combustion engines, as well as increased operational mass of transport and technological vehicles continuously aggravate the environmental situation in the world every year. (Research purpose) To identify the main impacts made by the transport and technological vehicles on the environment and the problems associated with their disposal, as well as with the disposal of automobile and tractor tires. (Materials and methods) The authors have generalized the materials published in periodicals, as well as the results of bench, field and operational tests of the transport and technological vehicles. (Results and discussion) The authors have identified the problem of the destructive impact of the wheeled movers on the supporting road surface, the soil and the soil cover. Measurements have been taken under the contact area of several mover types and the values of the stress-strained state of the soil affected by these movers have been determined in the form of the distribution of normal stress diagrams. The authors have also studied the influence of the design features of transport and technological vehicles performing curvilinear motion on the track size and soil destruction and identified characteristic patterns of the track. Conclusion has been made that in winter the level of environmental pollution depends on the road surface condition and the use of chemical reagents for deicing. The authors have considered a possibility of using electrical-and-hydraulic technology for the disposal of transport and technological vehicles and stressed the need to form regulatory documents for the designing, operation and disposal of transport and technological vehicles, taking into account foreign experience in organizing the environmental management system, as well as environmental auditing and labeling, the procedure for assessing the environmental performance of production systems and products at all life cycle stages. (Conclusions) The paper presents the main impact factors of the transport and technological vehicles on the environment during their life cycle up to full disposal. The authors have proved the need for a safe and energy-saving electro-hydraulic technology for the disposal of electronic components and batteries of transport and technological vehicles based on selective destruction of plastic casings and the separation of pure noble, rare-earth and other metals and their alloys.

Abstract. The development of a universal control system requires designing unified seed sowing sensors that allow controlling the sowing of seeds of different crops. (Research purpose) To provide theoretical grounds for the determination of parameters and installation location of a capacitive seeding sensor. (Materials and methods) In the course of the study, the authors have made theoretical calculations of the seed travel trajectories in mechanical and pneumatic sowing machines using the Mathcad and Microsoft Excel software systems, at various sowing machine frequencies: 11.5; 17.5 and 26.0 revolutions per minute as well as the calculation of the electrical parameters of the designed seeding sensor. Laboratory studies of the trajectory have been performed at the same rotational speeds of the sowing unit disc using high-speed seeding surveys on an experimental installation with subsequent processing of the obtained video materials. The optimum installation angle of the sensor has been experimentally studied from 0 to 67.5 degrees with a pace of 22.5 degrees to minimize the travel time of seeds through the sensitive area of the sensor, and as a result, to increase the sensor resolution using the developed software. (Results and discussion) Geometric and electrical parameters of the designed sowing sensor have been obtained, and its optimum location has been determined. (Conclusions) In the course of laboratory studies, data similar to the calculation results have been obtained; the relative value of the convergence coefficient between experimentally obtained and theoretical indicators does not exceed 0,55, provided these values are obtained at a distance less than the radius of seeds. The authors have experimentally determined the minimum distance between the sensor plates, which amounts to 20 millimetre, and calculated the electrical parameters of the sensor. They have also stated that the height of the sensitive zone should be at least 5 millimeters for reliable metering of individual seeds under these conditions. The obtained data allowed designing an experimental seeding sensor to determine the optimum angle and the sensor installation site. It has been concluded, that in order to minimize the travel time of seeds in the sensitive area of the sensor, the latter should be installed perpendicularly to the flight trajectory of the seeds.

Abstract. The paper presents the data on the energy intensity of the heat treatment of grain during post-harvest processing caused by both the cost of energy and the grain moisture content. The development of processing modes using electrical technologies, in general, and electromagnetic fields, in particular, can make it possible to reduce the cost of these processes. Heat treatment is applied to the grain of various crops at the stages of drying, disinfection, preparation for feeding, etc. When developing them, it is necessary to take into account the types of applied electrical technologies, such as, for example, infrared fields, microwave fields, etc. (Research purpose) To determine the dielectric properties (dielectric loss coefficient) of a wheat grain-air mixture with a moisture content of 11-30 percents with a layer density of 220-660 kilogram per cubic meter. (Materials and methods) The authors present a diagram of a laboratory installation, carried out experimental studies to determine the dielectric loss coefficient of a fluidized bed of wheat grain. (Results and discussion) The authors conducted a two-factor experiment to determine the effect of moisture and density of a grain bulk on the dielectric loss factor, which determines the power absorbed from the microwave source. As a result, they obtained the studied relationships. (Conclusions) It was found that the dielectric loss coefficient at a grain moisture content of 11-30 percents is in the range of 0.18-0.42 for a dense grain bed of 660 kilogram per cubic meter, 0.06-0.15 for a fluidized bed (440 kilogram per cubic meter); and for a weighted bed (220 kilogram per cubic meter) 0.1-0.3. The authors calculated a dependence of the dielectric loss coefficient of a wheat grain-and-air layer on the grain moisture content and the layer density, which can be described by a polynomial model of a second power. The study showed that fluidization of the grain bed increases the efficiency of the microwave field, as due to a decrease in the dielectric loss coefficient, the depth of field penetration into the layer increases. It is recommended to use the microwave field in a dense bed of grain when drying wheat, thus reducing moisture from 16 to 14 percent.

Abstract.The author has shown that modern technologies do not always meet the expectations of farmers, and this may adversely affect the pace of innovation. It has been confirmed that the developers of agricultural equipment do not clearly understand the context of the use of products and identified the need to use a multi-factor approach: therefore, partners possessing specific knowledge in different areas should join efforts in project activities at all stages of innovation. (Research purpose) To prove that a user-centered design and a multi-factor approach in the development of agricultural machinery increase their efficiency and accelerate the introduction of innovations. (Materials and methods) It is shown that Finnish research and development projects of agricultural machinery design involve numerous participants and end users. For example, the seven-metre-wide combi drill ‘Junkkari W700’ was designed by the Finnish manufacturer Junkkari Oy in close cooperation with end-users and researchers. As a result of the innovation process several benefits have been realized. The drill is easy to operate and service. The users appreciate the straight-forward construction and moderate cost of the drill as compared to competing pneumatic drills. The need for hydraulics is minimized and the row spacing and coulter design has been optimized so that economical tractors with moderate drawbar power can be used. The ISOBUS-based control electronics was designed to be fitted either in the existing tractor or, if ISOBUS is missing, with an optional cable-set and terminal. That enables the users to easily integrate the drill in existing machine chains, having either modern or older tractors, without extra tractor investments. Much attention was put on quality, e.g. individual feeders for every coulter give accurate dosage of seed and fertilizer. The prototyping together with end-users and researchers enabled Junkkari to speed up the innovation process. (Results and discussion) Several benefits proved to have been realized. First of all, the drill is easy to operate and service. The users appreciate the straight-forward construction and moderate cost of the drill as compared to competing pneumatic drills. The need for hydraulics is minimized and the row spacing and coulter design has been optimized so that economical tractors with moderate drawbar power can be used. The ISOBUS-based control electronics as well as an optional cable-set and terminal were designed to be fitted either in the existing tractor. That enables the users to easily integrate the drill in existing machine types, having either modern or older tractors, without extra tractor investments. The design quality was approved, e.g. individual feeders for every coulter give accurate metering of seeds and fertilizers. (Conclusions) The author proves that user-centered design and multi-factor approach methodologies have benefits both for the users and manufacturers. Swift innovation process saves resources and minimizes the need for excess iterations in the innovation process.

Abstract. Due to the increasing shortage of fossil fuels, the use of alternative energy sources is becoming even more popular. In Latvia, maize is predominantly used for the production of biogas, and other crops are being studied for this purpose. (Research purpose) To study the productivity of industrial hemp varieties (Cannabis sativa L.) and the possibility of obtaining biogas from hemp. (Materials and methods) Field experiments on hemp productivity were carried out on sod calcareous, heavy dusty sand clay soils in 2012-2014. Ten industrial varieties of hemp – 'Bialobrzeskie', 'Futura 75', 'Fedora 17', 'Santhica 27', 'Beniko', 'Ferimon', 'Epsilon 68', 'Tygra', 'Wojko', and 'Uso 31' – were sown with a seeding rate of 50 kilogram per hectare at the background of fertilizers: nitrogen – 120, phosphoric oxide – 90, potassium oxide – 150 kilogram per hectare. Hemp was sown on 10-square meter plots in mid-May, in triplicate. Hemp was harvested at the beginning of seed ripening phase. The whole crop of green mass was calculated on a completely dry matter. The fermentation process for the production of biogas, the average yield of methane, and other parameters were studied in the Laboratory of Bioenergetics of the Latvia University of Life Sciences and Technologies, using small-sized bioreactors. (Results and discussion) The dry matter yield of hemp obtained in the agro-climatic conditions of Latvia averaged 13.32- 17.78 tons per hectare. For an average of three years (2012-2014), higher yields of dry matter were obtained from the varieties of 'Futura 75' (17.76 tons per hectare) and 'Tygra’ (16.31 tons per hectare). The average amount of methane obtained from the 'Uso 31' leaves was 0.365 litre from one gramme of dry organic matter, which is a very good result as compared to other energy crops, for example, corn silage (0.319-0.330 litre from one gramme of dry organic matter in Latvia). (Conclusions) The research has demonstrated that hemp can be successfully used to produce biogas, and hemp leaves are the most suitable starting material.

Abstract. Automation of agricultural machinery is aimed at solving specific practical tasks: control and maintenance of the technological process quality, increasing labor productivity as well as crop yields. The method of "precision farming" is economically expedient, since it is a direct saving of technological material, as well as it helps reducing the negative impact on the environment and farm produce. (Research purpose) The research purpose is to review and analyze the main aspects required to develop the algorithms and software for motion control systems for a robotic tillage unit. (Materials and methods) To implement process control, it is necessary to control the direction of travel along a specified path, change the speed of movement depending on the engine load, switching the transmission gears. Physical-and-mechanical characteristics of the unit are rather heterogeneous and depend on weather conditions. Therefore, the algorithm for controlling the power of the robotic mobile unit must take into account, as much as possible, variations in the external effects of drawbar properties and the motion resistance, as a random factor. (Results and discussion) The authors have developed an imitation model representing the movement of a robotic unit. For the simulation, use has been made of a cyclic trajectory of the unit movement, consisting of two types of sections: the rectilinear ones reflecting the soil tillage pattern, and the turn areas where the unit makes a turn along a curvilinear trajectory around a certain center. (Conclusions) The implementation of robotic technologies in agricultural production result in increased technical, technological, production and economic indicators of agricultural units in field work, increased labor productivity, reduced time required for fieldworks, more rational use of bioenergy resources, increased yields of agricultural crops and reduced environmental impacts.