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The impact of local agrometeorological factors on beehive changing weight during sunflower (Helianthus annuus) flowering was monitored. The study was conducted in 2021 growing season in a hilly flat area with predominant agricultural crops. The location of the experimental apiary is 43°32'4.02"N and 25°45'14.10"E at an altitude of 223 m. The experimental apiary consisted of 122 bee colonies housed in Dadant-Blatt hives. The bees are of the species (Apis mellifera macedonica). The total number of fields sown with sunflower was 6. All sunflower fields were located within a radius of the bees' optimal flight area. During the experiment there were observed the outside air temperature (Tair), 0°C and air humidity (Hair)%, atmospheric pressure (Ap) hPa, soil moisture (Sm), % at 20 cm depth, soil temperature (St), °C at 10 cm depth, solar radiation (Sr) W·m-2, wind speed (Ws), m·s-1, precipitated rainfall (R), l·m-2. Also the air temperature inside (Tin) the hive was measured. The nectar flow is determined based on the changes in hive weight (Y). The real-time data were available via a web-based application Meteobot®. The results show that there is a significant positive correlation between Y and honey harvesting date D, honey harvesting time per day T, Tair, St, Ap. The other weather indicators as Hair, Sm Ws Dp, Tin are negatively correlated with Y. The indicator Sr is not correlated with Y. The monitoring of the agrometeorological factors and beehive weight during sunflower flowering will help the beekeepers determine the suitable moment for expanding the capacity of the hive and honey extracting. [ABSTRACT FROM AUTHOR]

The study aims to establish the relationship between the density of sown seeds, the gear ratio in the transmission system of the Saxonia A200 seed drill and the amount of seeds sown. A laboratory experiment was performed at the Department of Mechanization of Agriculture at the Agricultural University of Plovdiv. The main variables were the density of the material to be sown and the gear ratio (rotation speed of the seed drill). Each of the two factors changes on three levels. The experiment was performed with grass mixture seeds with a density of 250 kg⋅m-3, oats with a density of 537 kg⋅m-3 and wheat with a density of 825 kg⋅m-3. Gear ratio changes as follows: at the lowest gear the gear ratio is 70.5, at the highest gear the gear ratio is 1.25 and at the average gear the gear ratio is 35, 0. It was found that the gear ratio has a stronger effect on the change in the amount of seed sown compared to the density of the seed. About 61.1% of this change is due to the gear ratio and 33.3% to seed density. It was found that 5.6% of the change in the amount of seeds sown was due to other factors not considered in the present study. To determine the functional relationship between the factors and the observed indicator the regression analysis was performed. The corrected multiple correlation coefficient was R² = 0.937, confirming the strong relationship between the selected factors and the observed variable. The level of significance in the obtained model was p < 0.001. An adequate regression model is obtained, which can be used for forecasting and solving optimization problems. [ABSTRACT FROM AUTHOR]

An approach for evaluation of apiaries' location in flat-hilly regions by using a mathematical model is presented. The study was conducted in 2021 based on the assessment of the existing bee forage resources as Black locust (Robinia pseudoacacia), Linden (Tilia cordata), Sunflower (Helianthus annuus), Rapeseed (Brassica napus), Lavender (Lavandula) and the number of bee colonies kept in three different regions in the North-eastern part of Bulgaria. We use the mathematical model designed to estimate the potential location where hives can be placed, comparable to a coefficient characterizing the extent to which this place is desired to be created. The evaluation coefficient named ρi, preferably in a given place, the sum of the "values" of all feeding places in relation to the given apiary place are taken in consideration. Possible solutions are illustrated with numerical values giving assessment of potential distribution sites for cases without overpopulation of the area with bee colonies and for areas with overpopulation. The effectiveness of the proposed approach is reported in two directions. On the one hand, the benefit for beekeepers in their selection of suitable places for apiaries guaranteeing optimal nutrition of bee colonies. The correct assessment of the location will provide pollen and nectar for bees, reduction of harmful effects of overpopulation with bee colonies and high yields of bee products. On the other hand, the benefit for farmers growing flowering agricultural crops in the respective area is expressed in guaranteeing better pollination of crops, which is a prerequisite for higher yields. [ABSTRACT FROM AUTHOR]

A method is suggested for reasonable choice of tractors, agricultural machines and vehicles to implement linked field and transport processes based on easily accessible generalized available experimental data. Results of such procedure are site specific solutions appropriate for small farms. Basics of this method are power and forces balances for each definite possible machine and tractor unit. Resistant draft force is predicted according to the terrain, work period, tractor and machine undercarriage, weight of the unit and goods in the storage bunker, hopper, tank. Fuel consumption is estimated for all regimes: stopped engine, standby, unit idle, turning without productivity, work with or without movement, unit transit to a place for loading or unloading of the machine storage volume (bunker, trailer, lorry bodywork). Time utilization is calculated for two main cases - summary for the shift and for each working cycle. Each time expenditure is included in the shift duration base on official recommendations, experimental data and simple formulas. The above mentioned equations take into account the traveled distance in one cycle, field speed, amount of gathered product from the field or spreading product for a specific area. Particularly for transportation forward speed is calculated as a function of engine and transmission potential, terrain surface, road width, distance between places for passing of vehicles, traffic intensity. Selection is made by comparing of field and transportation capacity, fuel and labor consumption. For comparison, the working capacity is shown in the services area for a shift. Some differences of combined field and transport operations in cases of continuous and interrupted processes are considered. [ABSTRACT FROM AUTHOR]

An approach for mutually beneficial solving the issues of providing melliferous plants for honey bees and optimizing the necessary equipment and its use is presented. The plants must be included in appropriate crop rotations and pollinated by bees. To ensure strong bee colonies, field crops, varieties and hybrids with high potential nectar yields, overlapping flowering periods, with different vegetation durations and different sowing dates are offered. At the same time, appropriate land management projects take into account climatic and meteorological conditions, too. Possible solutions are illustrated with graphs of expected nectar productivity, need for machinery, staff, fuel in a production year. The effectiveness of the proposed approach is reported in two directions: on the one hand, the benefit for farmers growing agricultural crops is shown in terms of reducing the need for machinery, increasing the employment of service personnel for socially, economically and environmentally sustainable agriculture. On the other hand, the benefit for beekeepers corresponding area is expressed in providing pollen and nectar for bees throughout the honey harvest period, good stocking of bee colonies with honey, reduction of harmful effects of overpopulation with bee colonies, lower feeding costs, for transport and maintenance, high yields of bee products. The approach is suitable for application in flat-hilly areas with predominantly arable agricultural lands and, at the same time, with insignificant areas covered by forest and meadow flowering vegetation. [ABSTRACT FROM AUTHOR]

The trends in the change of the profitability of Bulgarian beekeeping starting from the country’s accession to the European Union (EU) in 2007 to the present 2020, are being studied, depending on the changes in the market price of honey and its prime cost. The survey was conducted among selected apiaries in North-eastern Bulgaria. It has been found that they achieve a small net profit when selling conventional honey in the organizational markets – EUR 3.78 kg-1. The realization of organic honey as a raw material in the organizational markets is not profitable for them. The apiaries have a net profit of EUR 7.98 kg-1 for conventional and EUR 7.91 kg-1 for organic honey, with distribution to a consumer market sale. The apiaries in Ruse district achieve 10.26% profitability of turnover in sales on conventional consumer markets, 8.83% in organic consumer markets and 8.2% in organizational conventional markets. Improving their profitability requires: 1) marketing strategies, through regional and cross-sectoral integration; 2) the production of royal jelly, pollen and propolis with high added value; 3) introduction of new technologies, increase in labour productivity, and 4) state subsidies to a hive for ecosystem pollination service. [ABSTRACT FROM AUTHOR]

Some problems in preparation of transport and field operations on large Bulgarian farms by using GPS and Google earth are discussed. The experimental investigations were carried out in experimental fields of the Institute of Agriculture and Seed Sciences (IASS) "Obraztsov chiflik" - Rousse. Hardware configuration - single Ashtec12 GPS receiver, GPS antenna, notebook computer, Garmin 205 GPS receiver; software configuration - system software GEOSURF SIZE1000 and Google earth software were used. The method of field experiment includes the next basic steps: measurement the point coordinate of 4 corners of the field, introduction of the work width of the work machine, distance between the GPS - work machine, outline of the field, work course, calculating the distance and route choice between the field and the farmyard, calculating the time for travelling and idle time. In the result of the field experiment a map for realization of transport and field operations in the IASS "Obraztsov chiflik" - Rousse is designed. [ABSTRACT FROM AUTHOR]