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

Evapotranspiration of a strawberry, ever-bearing variety Polka in three-year (2011- 2013) field experiments with drip irrigation on leached cinnamon forest soil in the area of Chelopechene, Sofia district. Different irrigation regimes have been tested: from fully satisfying the daily needs of the crop from water to irrigation with 20% and 40% reduced irrigation rates. During the research period, the total evapotranspiration rate for the strawberry growing season was 213 mm in average. Average 24-hour values vary by date. The highest are in the first and second ten-day period of June (harvest period).

Drought is a major problem for plant breeding in the country during dry years. This, in parallel with the increase in the technical capabilities of agriculture, has put more emphasis on overcoming the drought phenomenon. For this purpose, efforts have been made both in the development of relevant technical concepts and in the development of appropriate methodologies and technologies. The most important activity in this direction is the redistribution of water resources mostly over time. The report presents some aspects of overcoming the effects of drought by optimizing the use of water resources.

The deficit of the irrigation water requires irrigation technologies of more efficient water use. For cucumbers the most suitable is the drip irrigation. For establish the appropriate irrigation schedule of cucumbers under the soil and climate conditions in the village of Chelopechene, near Sofia city, research was conducted with drip irrigation adopting varying irrigation schedules – from fully meeting the daily crops water requirements cucumbers to reduced depths with 20% and 40%. Have been established irrigation schedule, irrigation water productivity and yields of in plastic unheated greenhouses of the Sofia plant.

Analysis of meteorological factors shows that the temperature sums during the vegetation of the main crops grow but are relatively stable, ie. they are not a limiting factor for their normal growth and development. Rainfall, however, in terms of quantity and distribution changes in a considerably wider range over ten days periods, months and years. The instability of this meteorological factor predetermines irrigation as a major event of the agro-technical complex, which is decisive for the achievement of high and sustainable yields.

Increasing water deficit requires the use of water-saving irrigation technologies in the practice of irrigated agriculture and the conduct of research to optimize irrigation regimes in order to increase the efficiency of irrigation water used. One of the ways to achieve this goal is irrigation with reduced irrigation norms while preserving the number of waterings. The advantage of these reduced irrigation regimes is the saving of water at acceptable yield losses. Their application is warranted when there is a possibility of accurate dosing of irrigation water and the irrigations are of low cost.

In order to establish the irrigation regime of apples in drip irrigation, field experiments were carried out on the Chelopechene-Sofia experimental field. Irrigation is carried out with a drop in pre-watering humidity to 85% of WHC and variants irrigated by a reduction of irrigation rate with 20% and 40% compared to the variant irrigated at 100% WHC and non-irrigated variant.
The conducted irrigated regimes during the years have had an impact on the yields obtained, with the highest results being obtained for the irrigated variants with 100% irrigation rate and the lowest for the non-irrigated variants. The largest increase in yield was obtained in 2004 (characterized as dry), which is with 55% (apples) more than non-irrigated variants, and the smallest increase of 25% (apples) was obtained during the humid 2005.

In order to establish the parameters of the dependence of irrigation norm – yields of long – fruit cucumbers a field experiment was carried out in the period 2001-2004, on a chromic luvisols soil (chromic forest soil) . Different irrigation regimes have been tested – from full satisfaction of the culture’s daily needs of water, to irrigation with irrigation norms reduced with 20% and 40% .The soil moisture content in the layer 0-0.5 m is used as a criterion for determining the time for making a polish. Under optimal variant (variant 2), the same is maintained with over 85% of WHC.
It has been found that reducing the irrigation rate leads to a corresponding reduction in yield but it is disproportionate. In all cases, the reduction in yield is less than the decrease in the irrigation rate.Parameters of “water-yield” dependency are determined by the two-step formula of Davidov, which approximates the test points by S-curve at a correlation coefficient R = 0,999. The results show the variation of yields depending on the reduction of the irrigation rate. In the calculations obtained, the values of the gradation indicators n = 2,25 and m = 1,48 can be used to optimize the irrigation regimens of long-fruit cucumbers.

The production of green beans in plastic unheated greenhouses is relevant when grown as a intercropping culture. Rrotation of crops is an important biological factor for increasing soil fertility, and year round production of vegetables in plastic greenhouses to maximize the economic impact of these expensive facilities.
Considering the biology of the crop and especially its requirements for soil moisture, determinating for obtaining high yields and quality production is the implementation of a proper irrigation regime, as well as the use of suitable irrigation technique.
The aim of the research is to identify the main elements of the irrigation regime of green beans, cultivated as a second intercropping culture, in drip irrigation / watering and irrigation rates, interwatering periods and number of irrigations /.
Irrigation was carried out with a drip irrigation system type Drossbach. Variations have been tested at 85-90% of pre-watering humidity and 120% of irrigation rates- 120%; 100%; 80% and 60%.
It has been found that the productivity of irrigation water in drip irrigation of vegetable crops grown in unheated greenhouses is increased by reducing the irrigation rate. The highest productivity of irrigation water is achieved with the 60% irrigation rate option.

Analysis of meteorological factors shows that the temperature sums during the vegetation of the main crops grow but are relatively stable, ie. they are not a limiting factor for their normal growth and development. Rainfall, however, in terms of quantityand distribution changes in a considerably wider range over ten days periods, months and years. The instability of this meteorological factor predetermines irrigation as a major event of the agro-technical complex, which is decisive for the achievement of high and sustainable yields.
Increasing water deficit requires the use of water-saving irrigation technologies in the practice of irrigated agriculture and the conduct of research to optimize irrigation regimes in order to increase the efficiency of irrigation water used. One of the ways to achieve this goal is irrigation with reduced irrigation norms while preserving the number of waterings. The advantage of these reduced irrigation regimes is the saving of water at acceptable yield losses. Their application is warranted when there is a possibility of accurate dosing of irrigation water and the irrigations are of low cost.
In order to establish the irrigation regime of apples in drip irrigation, field experiments were carried out on the Chelopechene- Sofia experimental field. Irrigation is carried out with a drop in pre-watering humidity to 85% of WHC and variants irrigated by a reduction of irrigation rate with 20% and 40% compared to the variant irrigated at 100% WHC and non-irrigated variant.
The conducted irrigated regimes during the years have had an impact on the yields obtained, with the highest results being obtained for the irrigated variants with 100% irrigation rate and the lowest for the non-irrigated variants. The largest increase in yield was obtained in 2004 (characterized as dry), which is with 55% (apples) more than non-irrigated variants, and the smallest increase of 25% (apples) was obtained during the humid 2005.

Experimentally, the evapotranspiration and evaporation from the free water surface of long-fruit cucumbers grown under greenhouse conditions was established. Based on the calculated values of the evapotranspiration based on the soil humidity dynamics data during the vegetation period, the irrigation carried out and the evaporation from the free water surface determined by a class “A” evaporator, the values of the coefficient of the culture in unheated plastic greenhouses were calculated as an average for the vegetation process of cucumbers Ki is 1,46. Establishing a correlation between ET and Eo under greenhouse conditions allows a safer use of Class A evaporator data.

Berry cultures – strawberries, raspberries, blackberries, blackcurrants, etc. are of great economic importance due to growing demand and high productivity. In general, they are susceptible to droughts and are so demanding for soil moisture, and their growth and yield depend to a large extent on the presence of sufficient soil moisture.
In order to establish the irrigation regime of raspberriesin drip irrigation conditions, field experiments were conducted on the experimental field Chelopechene-Sofia. Irrigation was carried out with a pre-irrigation humidity less than 85% of WHC and variants watered with irrigation rate reduction of 20%, 40% compared to the variant irrigated at 100% of WHC and non-irrigated variant.
Realized irrigation regimes in individual years have had an impact on the yields obtained, with the highest yields being obtained for the irrigated variants with 100% irrigation rate and the lowest in non-irrigated variants. The highest increase in yield was obtained in 2004 (dry), which is with 67% more compared to non-irrigated variants, and the smallest increase of 33% was obtained in the humid 2005.
The analysis of meteorological factors shows that the rainfall in the country is insufficient to satisfy the requirements of plants of soil moisture, and the temperature sums over ten-days periods over the whole vegetation period considerably exceed the respective norms. This requires the use of drip irrigation for the successful production of raspberries under conditions of water deficiency and relatively high temperatures.

Drip irrigation provides a fairly even mode of moisture in the soil and, along with this, favorable air, heat, microbiology and nutrition. As a result, there is an increase in yields and an improvement in the quality of production.
In order to determine the impact of drip irrigation, on the size of the yield and the economic indicators, in the cultivation of raspberries in the soil and meteorological conditions of the area of the village of Chelopechene – Sofia researches of an everbearing variety “Lyulin” were carried out. Various options have been tested – from fully satisfying the daily needs of the culture by water, irrigation with 20% and 40% irrigation norms to non- irrigating conditions.
The results obtained in years with different security of meteorological factors show that the drip irrigation of raspberries has a positive effect on the economic indicators of its cultivation, the costs of creating the raspberry crop, the irrigation system and the cultivation of the crop are redeemed for two or three years.

The increasing water deficit requires studies to optimize irrigation regimes and water-saving technologies to achieve economy of irrigation water at an acceptable yield level.
In order to establish the irrigation regime in the field of “Chelopechene” Experimental Field, Sofia, there have been researches, examining different regimes – from full satisfaction of the daily needs of culture for water to irrigation with reduced by 20% and 40% water application rates.
On average, over the survey period, the highest yields were obtained with the irrigated wit 100% water applicatipn rate. Reducing the irrigation rate leads to a corresponding reduction in yields and affects the quality of production. The application of regimes of irrigation with reduced iwater applicatipn rates is recommended  only in the case of water deficiency.

To determine the effect of magnetically treated seeds on the productivity of tomatoes and onion in the area of the Sofia field experimental experiments were carried out with variants with magnetically treated seeds and variants without magnetic treatment of the seeds. Irrigation has been dripped in optimum irrigation mode. The yields obtained with the processed tomato seeds in tomatoes are up to 22% higher than those of untreated and onion onions to 28%, respectively.