International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Determining the sustainability of agricultural production are agro-technical activities, as the main units in any technology. A study has been carried out to evaluate the impact of crop treatment systems, mineral fertilization and integrated weed control on soil and climatic conditions in the Sofia region.
It has been found that less intensive weeding with annual and perennial weeds is observed when using a more intensive treatment system compared to the reduced treatment option. The number of weeds per unit area is increasing in the non-fertilizing variants, but their mass is lower than the fertilizers. Deeper soil tillage contributes to maintaining the values of the physical parameters (humidity, bulk density and soil hardness) in a more favorable range. Fertilization has the most significant effect on yields during the three years of the experiment.

Research of efficiency of conventional production of mercantile corn was held on production parcels in agroecological conditions of Posavina in a period of vegetation in 2017. In order to define costs of crop management from the point of view of energy and production aspects, in certain stages of production of corn grain, energy consumption and utilization of the horsepower of the tractor was monitored. During working operations the maximum amount of fuel was spent for ploughing ( plough Leopard- L 30.3 VK aggregated with tractor Belarus 82.1 ) 26,4 l/ha, while the smallest amount was spent in chemical crop protection ( sprayer RAU aggregated with tractor Universal UTB 450 ) 2,7L/ha. Accordingly, efficiency in various operations of production varied within 10-20% span. In our experiment efficiency varied from 6,91% during fertilization to 23,33% in the process of ploughing, which is in this case within optimum limits. In direct input almost one third or 27,13% went for the basic tillage system ( 81,77 kWh/ha ) with a very high fuel usage of 23,33%. If we look at energy value of production of corn grains energy output will be 75243,20 MJ/ha with a ratio of 16,178 which is considered to be quite high, and productivity of 1,273 kg/MJ. In order to get the full picture of the above production of corn and energy outcome and not concentrating only on grain production, it is essential to include in energy analysis significant amounts of plant residues, that is maize biomass, which doubles the mentioned energy ratio to 31,846 and hence overall productivity of energy circulation in this production.

Sowing quality means required vertical (depth) and horizontal (spatial) spacing of seeds in the soil with minimal damage to the seeds. The spatial distribution of seeds (horizontal spacing) is given by distance between the rows and spacing of the seeds in a row. The objective of the study was the evaluation and comparison of the sowing quality of sowing machine jd maxemerge xp with mechanical filling of ladle holes with holding fingers within usage of seeds with different dimensional and shape attributes in agricultural conditions. Sowing machine jd maxemerge xp reached good results for the quality especially when using the angular seeds. It reached the sowing quality expressed by the standard deviation of 46.95 – 50.76 % when seeds pr 37 n01 and for seeds pr 37 n01 it is 47.43 – 48.73 %. Another evaluative criterion is dual sowing of seeds or plants (drr), it was reached the average value 3.65 – 2.45 % for angular seeds and the average of 1.54 – 3.71 % for approximately spherical seeds.

Sustainability of agricultural production results in reducing the negative trends caused by both climate change and by incorrectly applied technologies for production, which aims to preserve the resource base and maintaining environmental quality. Soils are conditionally renewable natural resource but practically reconstruct in a very long time. Therefore, in order to preserve them relate to nonrenewable natural resources. At its core, soil, where they are intended for agricultural use are processed to meet the needs of people and thus change their properties. By applying appropriate ways of tillage and use the potential of plant residues, it is possible to control physical properties. There is a misconception and myth that getting high yields in agriculture can be maintained only with the addition of fertilizer and / or water. High investments made at the entrance of the agricultural production can easily be pointless, if the physical properties of soil are suboptimal or even below the critical level.The physical properties of the soil, it is essential for processing and has its mechanical structure. It closely depend on a number of other properties such as bulk density, ability to retain water, porosity, adhesion, resistance, etc., Which play an important role in the processing and to obtain sustainable yields.

The region of Varna proved to be a driest in terms of precipitation in this country. Trend test applied to climate datasets reviled a significant increase for seasonal reference evapotranspiration ETo during 1970-2004. Detected climate variability&droughts create uncertainties for maize irrigation scheduling and harvested yield. To cope with them, simulations have been performed for past (1951- 1984) and present (1951-2004) weather conditions using the validated water balance WinISAREG simulation model for two maize hybrids of different sensitivity to water stress grown on a Haplic Chernozem soil of medium water holding capacity. The study compares three irrigation scheduling alternatives built in agreement with past studies to develop environmentally sound/water saving irrigation technologies that consist of refilling the soil reservoir by adopting a management-allowed depletion fraction (MAD): (1) MAD=0.50; (2) MAD=0.33; (3) MAD=0.50 but partially refilling the soil reservoir. Simulations relative to the very high irrigation demand year of the current weather show that when aiming at maximum yield all three scheduling alternatives require the same irrigation depths ID=360mm that is 60 mm higher than conventional advised in the region. In the average demand years of past and current weather, Alternative 1 requires the same ID=270mm while a smaller ID=240mm is simulated with both alternatives 2 and 3 due to the fact that available soil water ASW is presently depleted to the optimum yield threshold OYT at harvest.