Table of Contents


    • Substantiation of the process of deep tillage with agricultural machines of digging type

      pg(s) 86-89

      The paper considers the issue of deep tillage, the use of the latest technical advances, in order to develop new tillage implements that provide better tillage and reduce erosion. The main attention is paid to the preservation of soil fertility and the use of funds in organic farming. The aim of the work is to improve the process of mechanical tillage by digging by developing a new working body and the process of interaction of digging working bodies with the soil, which change its physical properties and improve environmental safety. The most promising for deep tillage is the digger in terms of both energy and agronomic indicators (reduction of compaction, preservation and restoration of water and air balance, preservation of humus, preservation of biomass). Rotary diggers with rotational movement of working bodies are more effective in comparison with diggers having oscillating movement of working bodies. As a result of studying the dependence of the angle of the blades, providing the movement of the formation on the surface of the working body, from their position on the trajectory, it was found that the smallest value (5…70) is the angle of inclination after turning the blade deepening. When lifting the formation from the bottom of the furrow to a certain height, the required angle of the blades increases, reaching a value of 28… 300 when overturning the formation at a height of 0.20…0.25 m

    • Assessment of agrotechnical indicators of the seeder for sowing grass seeds

      pg(s) 90-93

      Field laboratory tests of the seeder under development with the intellectual control unit for the technological process of sowing non-loose grass seeds, consisting of a frame, seed box with sowing devices, attachment, sowing section, running gear and sowing device drive, were carried out on the territory of the University’s research and production campus, which was divided into plots 37 * 3,6 m in size.
      The following parameters were adopted for the breadboard model of the seeder: speed of movement 7 km / h; seed placement depths of 2 and 4 cm. Aisle spacing of 30 cm was taken. The maximum and minimum seeding rate for the selected crop was defined.
      An analysis of laboratory tests of the seeder showed that the sowing ability of the seeder is 8-30 kg / ha, while the unevenness of the sowing was 4,60% when sowing grain and 4,80% when sowing the awnless bun. The instability of the total sowing is 2,90% when sowing wheat grass and 2,7% when sowing the awnless bun.
      The field germination of “Burabay” wheatgrass seeds in experimental plots amounted to 90%, and on the plot sown with awnless bun “Akmolinsky Emerald”, the germination rate was 89%; the uniformity of the seeding depth of the seeds of the prototype seeder is 6,28% in the sowing of wheatgrass, and the sowing of the awnless bun is 5,78%; the number of seeds embedded in the layer of average actual depth and two adjacent layers on the sowing of wheatgrass was 91% and on the sowing of awnless bun is 90%, which corresponds to agro technical requirements; when testing a prototype planter of the seeder, the distribution of seeds over the feeding area was 62% for the sowing of grain and 64% for sowing of the awnless bun.
      An analysis of the results of laboratory field tests of the seeder showed that, according to the quality indicators of the technological process, the developed seeder meets the agro technical requirements for grass sowing and is not inferior to foreign seeders and it is necessary to conduct its extended field tests.

    • Technologies for soil surface maintenance in perennials

      pg(s) 94-96

      Perennials are an important strategic sector for agriculture in Bulgaria. In order to obtain good results from their cultivation, a scientifically based system for the maintenance of the soil surface is needed. Existing technologies have been analyzed to support the selection of an appropriate soil maintenance system. The size of the agricultural holdings in Bulgaria for the most widespread perennial plantations, which are the vineyards and are substantiated by economically expedient technologies and machines for soil cultivation suitable for the majority of the agricultural producers, is analyzed. The advantages and disadvantages of the technologies and the machines for their realization are presented.

    • Experimental research of agricultural bridge unit in the state of harrow aggregate

      pg(s) 97-99

      From the standpoint of energy saving, the issue of research of agro-bridge units in the composition of new agricultural lands adapted to them is important and relevant tools that operate on the principles of track and bridge farming. One of the latter is a heavy tooth harrow with flat segments. Experimental determination of the characteristics of the agronomic bridge harrowing unit in its composition, in order to establish compliance of its parameters with the basic principles of the effective implementation of track and bridge farming, was adopted as a research objective. Experimental research was carried out both according to generally accepted and developed methods, and provided for the use of modern strain gauge and control equipment with analog-digital conversion of signals from information sensors. The processing of experimental data was carried out on a PC using probability theory, regression, and correlation-spectral analysis. Physical objects of researches were wide-track agricultural bridge construction vehicle TDATU with its track width of 3.5 m and harrowing machine (BZSS-1.0 type). According to the results of experimental tests of agricultural bridge harrowing unit as part of the dental harrow proved its good adaptability to work in the units of track and bridge farming and high quality of the technological process. The latter is also a consequence of the fact that the movement of the agricultural bridge is carried out on the compacted traces of a constant tramline, whose roughness profile is low-frequency in comparison with the longitudinal profile of the harrower. The constructive version of the tooth harrow is well reflected in the nature of its unevenness in traction resistance. It is established that the fluctuations of the harrow’s traction resistance express a random function in which there are no harmonic components. The coefficient of variation of resistance fluctuations on the hook of the agricultural bridge during harrowing is no more than 10%. The latter indicates a high stability (low variability) of the process of harrowing the soil, has a positive impact on the stable movement of the agricultural bridge unit.


    • Computerized ecotechnology for managing crop water status making agricultural activities more efficient and protecting the environment

      pg(s) 100-102

      The paper deals with the perspectives for developing ecologically based biological agriculture in Bulgaria, the European Union and the other countries. Innovative technology (for computerized monitoring the soil water deficit and scheduling the irrigation) replaces the periodical local (point) measurements of soil moisture. Its application helps to be taken into account the physiological features of crop, creating appropriate energy level of soil moisture through ecologically accepted watering technique in each agricultural crop field. It ensures to be obtained the scientifically planned amount and quality of crop yield, saving on average 30 % of irrigation water and one third of nutrients added for plants.
      New universal estimation of crop water status, current computerized monitoring of the water deficit in root zone of soil, and exact management of productivity are possible to be accomplished.
      Data were obtained under field conditions over 30-year research period. Fundamental physical laws and recent Bulgarian and foreign world-top scientific achievements were aggregated and applied to be created the new scientific basis of the technology.
      The obtained results showed the successful applications of: (a) the new hydro-physical index and the method for its determination under both non-irrigation and irrigation conditions and (b) the Technology for Monitoring, Estimating and Managing (TMEM) of the water status of this layer in irrigation rural activities, taking into account the European ecological requirements. The technology is easily applied as Decision Support System (DSS) in irrigation agriculture.

    • A decision support system for field vegetable fertilization

      pg(s) 103-107

      Decision Support System (DSS) is a computer-supported interactive system, i.e., a software product to assist decision-making at any level of management, with an emphasis on making a directly applicable decision. The purpose of this software for the application in the process of fertilization is to organize and classify data, transform information, and choose how to make decisions and embody them. In its sophisticated form, it is an interactive computer program that uses and integrates a simulation model, a database and a decision model for optimal crop fertilization with different fertilizers. Fertilization recommendations in most countries around the world are based on years of fertilization experiments. When using DSS, the user must enter 3 data groups: 1) the type of vegetable and the planned yield; 2) results of agrochemical soil analysis (soil pH, soil organic matter content, available phosphorus and potassium, mineral nitrogen); 3) plans for organic fertilization and available fertilizer data. The flowchart of DSS main part consists of 12 steps: 1) determination of target yield 2) calculating the required amount of nutrient for the target yield; 3) calculating the optimal need of N in fertilization 4) calculating the optimal need of P and K in fertilization 5) determination of optimal organic fertilization; 6) calculation of the liming needed; 7) optimal distribution of N 8) optimal distribution of P and K with respect to fertilization dynamics; 9) the need and plan for application of micronutrients; 10) choosing the optimal form of nutrient and calculating the amount of optimum fertilizers (single and complex) 11) calculation of the nutrient balance 12) calculating the economic effect of vegetable fertilization and growing. DSS groups results into several sets of data: 1) interpretation of the results of agrochemical properties and soil fertility; 2) recommendation of the quantity of N, P, K and types of fertilizers (required quantities of primary nutrients in mineral fertilization of vegetables, types and quantities of mineral fertilizers required for the mentioned fertilization); 3) balance of primary nutrients, tips and warnings (optimal formulation of fertilizers, the balance of planned mineral fertilization, needs of fertilization with microelements). After receiving the results and guidance, the user simply obtains new output values according to the changes made by simply changing the input data (e.g., to plan a lower yield, other formulation fertilizer, cheaper fertilizer). This mode of operation enables rapid multiple comparisons of the required fertilization with different available fertilizers, on different production sites, and for different target yields and economic effects of vegetable cultivation.

    • Sunflower irrigation in conditions of water deficit

      pg(s) 108-110

      An analysis has been made of the research work to determine the impact of water deficit on the quantity and quality of sunflower production. Studies have also taken into account the more frequent drought in the last decade – soil and atmospheric. Research shows that its good drought resilience allows it to be grown under irrigation conditions, but is sensitive to severe droughts, especially in the critical stages of development which leads to poor quality and drastic decrease in yield, and in some years to the lack of yields. The results show that sunflower irrigation has a large reserve for obtaining additional yield, which has been established through experiments in different parts of the country. The increase in irrigation is about 30-40%, and critical for water stress is the period of 20 days before and 20 days after flowering.

    • Microbial indicators and their relations with hydrophobicity in Spolic Technosols under different vegetation

      pg(s) 111-114

      Hydrophobicity (water repellency) have negative impact on soil structure, plant growth and production. The knowledge on soil hydrophobic properties is important for proper amelioration of water repellent soils. A monitoring study on hydrophobicity level, microbiological indicators and the realtionships between them in a coal ash reclaimed Technosol under different vegetation cover (pine trees, acacia trees and stubble) was performed. It was found that the surface layers possessed extreme or severe hydrophobicity and below 30 cm depth the soil was slightly hydrophobic. The structure of microbial population changed depending on vegetation. Oligotrophic microorganisms dominated in soils under trees and fungi prevailed in the soil under stubble. The soil under pine trees had the highest microbial parameters. Soil hydrophobicity level was very highly positively correlated with the amount of fungi in both areas under tree vegetation. Under stubble, negative correlation of WDPT with fungi and cellulolytic microorganisms was found. Relations with basal respiration and microbial biomass carbon were weak.

    • Evapotranspiration and biophysical coefficients of large-fruited tomatoes grown in unheated greenhouses under drip irrigation

      pg(s) 115-117

      To determine the overall and average evapotranspiration of tomatoes grown in unheated greenhouses, studies were conducted under soil and meteorological conditions in the area of the village of Chelopechene – Sofia with drip irrigation.
      The total evapotranspiration, which reaches 537 mm during the vegetation period of the crop, is experimentally determined, and the established daily evapotranspiration values range from 1.50 to 5.5 mm with two minima – at the beginning and end of the growing season and one maximum in August. . For the purposes of practice and design, the daily values of the biophysical coefficients Z, R and Kp are also calculated, which depends on the biological characteristics of the crop and the meteorological factors.