THE EFFICIENCY OF DIFFERENT MOISTURE AND NUTRITION CONDITIONS IN EARLY POTATO GROWING UNDER DRIP IRRIGATION IN SOUTHERN UKRAINE

: The article presents field research results on the effectiveness of different moisture and nutrition conditions at the cultivation of early potato under drip irrigation in southern Ukraine. The scheme of the experiment included the treatment with the complex Mochevyn K as an additional control and different methods and correlation of fertilizers Rlantafol (treatment of tubers before planting, fertilizing, at budding and their combination), as well as different soil moisture conditions (irrigation rates of 100 and 200 m³/ha). Studies have shown that the average yield of early potato without irrigation was 10.44 t/ha. Moisture conditions significantly affected the yield of young tubers – irrigation at a rate of 200 m³/ha provided 21.61 t/ha, whereas reducing the irrigation rate to 100 m³/ha led to a decrease in yield – 19.86 t/ha. The first treatment of planting tubers, treatment of plants at sprouting and during budding provided almost the same yield. The second and the third treatments of plants and tubers did not lead to a significant increase in yield. The highest productivity of potato was provided by Plantafol treatment of tubers and combination of tuber treatment with foliar feeding at mass sprouting phase with a 200 m³/ha irrigation rate for two years: 24.16 and 23.22 t/ha.


Introduction
The issue of fertilizer efficiency in the conditions of each zone needs constant improvement, as evidenced by research conducted in our and other scientific organizations. It is determined that the correct use of fertilizers provides a 40-50% and even higher increase in yield (Bondarchuk and Molotsky, 2007;Yaroshko, 2012;Hamayunova and Iskakova, 2015;Mʺyalkovsʹkyy, 2017). Plant growth Golovatsky, 2009). The Institute of Irrigated Agriculture of NAAS studied the regime irrigation for summer planting potatoes. For the conditions of the middle of the year, the irrigation regime of 70-80% field capacity was developed during the period of tuber formation which involved four waterings (irrigation norm of 2000 m 3 /ha) (Pisarenko and Golovatsky, 2005). Later, the Institute has updated the data: total water consumption of potato is 2100-4100 m 3 /ha by vegetation, an irrigation rate for medium loamy soils during sprinkling is 350-400 m 3 /ha, with drip irrigation -250-280 m 3 /ha (Balashova and Yuzyuk, 2016;Kyslyachenko, 2014;Yuzyuk and Balashova, 2017).

Material and Methods
The experimental part of the research was performed on irrigated lands of the Institute of Irrigated Agriculture of NAAS (IIA NAAS), located on the right bank of the Dnieper; the Dnieper district of Kherson in the area of the Ingulets irrigation system.
The soil of the experimental plots is dark chestnut medium-loamy slightly saline on the carbonate loess, typical for the irrigated zone of the South of Ukraine. The content of humus in the arable layer is 2.2%, total nitrogen -0.17%, mobile phosphorus -30 mg/kg and exchangeable potassium -300 mg/kg. Field capacity in a meter layer of soil (FC) is 21.3%, wilting moisture (WM) -9.5% by weight of dry soil, structure density -1.41 t/m 3 , pH of the aqueous extract of the arable soil layer is 6.8-7.2. Groundwater lies at a depth of 18-20 m and has virtually no effect on the water-air regime of the zone of active moisture exchange.
The data of the Kherson agrometeorological station located on the territory of the Institute were used to characterize the weather conditions during the research years.
Agrotechnic in the experiment corresponded to the technology of growing potatoes in the South of Ukraine, the requirements of research methods and guidelines for conducting research with potatoes; mathematical processing of experimental data was carried out according to generally accepted methods (Kutsenko et al., 2002;Ushkarenko et al., 2014;Vozhehova et al., 2014).
The task of the research was to establish water consumption of potato plants depending on the conditions of hydration and fertilization with macro-and microelements; to determine the influence of drip irrigation and fertilization with macro-and microelements on the growth, development of potato plants, crop formation; to establish the effectiveness of various irrigation standards and fertilizing; the substantiation of the economic efficiency of technology elements of potato plant watering and feeding for obtaining early potatoes. To solve the tasks in the laboratory of potato biotechnology IIA NAAS during 2014-2015, a field experiment was conducted, the scheme of which is given in Table 1. Foliar feeding with Plantafol in the sprouts phase 5. Foliar feeding with Plantafol in the budding phase 6. Treatment of tubers + feeding with Plantafol in the sprouts phase 7. Treatment of tubers + feeding with Plantafol in the sprouts + feeding in the budding phase The following preparation was used for the experiment: Mochevyn K is a developer and manufacturer of Limited Liability Company Research and Production Association "Agronaukovets". Active substances include N (13%), P 2 O 5 (0.3%), K 2 O (0.15%), microelements (0.1%), succinic acid (0.1%), organic acids, and tricarboxylic acid complex.
Mochevyn K6 accelerates the formation of the root system and the emergence of sprouts. The method of application is the treatment of seed tubers. The consumption for potato is 1 l/t of tubers. Mochevyn K1 stimulates the development of the root system, aboveground mass, strengthens the immune system of plants. The method of application is fertigation, foliar feeding. The consumption potato is 1 l/ha. Mochevyn K2 increases the drought resistance of plants, thickens stems due to the blockade of growth hormones and growth regulators, forms additional sprouts. The method of application includes foliar feeding. The consumption for potato is 1 l/ha (data of Limited Liability Company Research and Production Association "Agronaukovets").
The treatment with the complex Mochevyn K includes the treatment of tubers before planting of Mochevyn K6, treatment in the sprouts phase of Mochevyn K1, treatment in a budding phase of Mochevyn K2.
Plantafol is a complex water-soluble fertilizer containing microelements for fertilization during the growing season and the treatment of tubers. The treatment of planting tubers implies Plantafol N 10 P 54 K 10 at the rate of 1 kg/t of tubers, and the consumption of a working solution of 20 l/t. The treatment in the sprouts phase implies Plantafol N 30 P 10 K 10 at the rate of 3 kg/ha, and the consumption of a working solution of 250 l/ha. The treatment at the budding phase implies Plantafol N 5 P 15 K 45 at a rate of 3 kg/ha, and the consumption of a working solution of 250 l/ha.
The study was conducted with a medium-early potato variety Nevska. The area of the first-order plots was 54.9 m 2 , the accounting area was 41.2 m 2 , the area of the second-order plots was 7.8 m 2 , the accounting area was 6.37 m 2 . The feeding area was 70 × 32 cm, three repetitions.
The efficiency of different moisture and nutrition conditions in potato under drip irrigation 5 Potato in the experiment was planted in spring and harvested after mass flowering (early harvest); the predecessor was winter wheat. Planting density ware recorded in the experiment after emergence and before harvesting; observations of soil moisture were conducted during planting and at the following phases: sprouting, budding, flowering, after harvesting at 0.5-m depth; crop accounting with the definition of its structure was carried after the end of mass flowering.
The following methods were used in the study: field, biometric, measuringweight, variance and correlation-regression analysis, system analysis and synthesis, economic analysis.

Results and discussion
To provide the specified conditions of moisture before early harvest in 2014, 4 waterings were required at the rate of 200 m³/ha, and 7 at the rate of 100 m³/ha, and in 2015, 5 waterings at the rate of 200 m³/ha, and the rate of 100 m³/ha -8. The irrigation norm in 2014 at an irrigation rate of 200 m³/ha was 800 m 3 /ha, and at 100 was 700 m 3 /ha; in 2015 -1000 and 800 m 3 /ha. The average irrigation norm for two years at an irrigation rate of 200 m 3 /ha was 800 m 3 /ha, and by 100-750 m 3 /ha (Table 2). Observations of soil moisture in 2014 showed that in variants without irrigation, the humidity of the 0.5-m layer was at 72% of the field capacity due to precipitation in early May, before budding. Moreover, at the beginning of flowering, soil moisture decreased to 60% of the field capacity, and the plants began to suffer significantly from its lack (Figure 1).
The precipitation between June 1 and 7 somewhat slowed down the drying of the calculated soil layer, but practically did not replenish moisture reserves. The most critical situation occurred during the period of full flowering, when the crop of tubers was intensively formed -soil moisture decreased almost to the humidity of wilting, and water supply of plants was from deeper layers of soil. In the third decade of June, heavy rains slightly improved the water supply to plants, but this almost had no significant impact on plant growth and development and tuber formation. In 2015 the weather was more favorable for potato culture. The humidity of 0.5 m soil layer on the plots without watering, due to precipitation during April, before budding, was at the level of 60% of field capacity. During budding there were heavy rains, which replenished soil moisture to 100% field capacity. And at the beginning of flowering soil moisture was 80-75% of field capacity ( Figure 2). Conditions prevailing during budding-flowering contributed, on the one hand, to the intensive growth of aboveground mass of plants, and on the other hand, there was not enough of moisture, which led to soil moisture decrease to critical values in the early second decade of June -41-42% of field capacity, which is badly affected in the process of crop accumulation. The precipitation on June 26-27 somewhat slowed down the drying of the calculated soil layer, but practically did not replenish moisture reserves, and the water supply of plants was due to deeper soil layers with relatively few roots, which had an insignificant effect on plant development and potato tuber crop formation.
Irrigations at a rate of 200 m³/ha provided soil moisture during the budding phase at the level of 81-100% of field capacity, and during flowering not less than 82%. Before harvesting, due to precipitation (June 17-28 in 2014 and June 26-27 in 2015), soil moisture amounted to 77-98% of field capacity. With irrigation at a rate of 100 m³/ha, soil moisture did not decrease less than 82% of field capacity before harvest. Potato water consumption without watering from a layer of 0.5 m before early harvesting was 1877 m³/ha, on the average of two years; of which 49.1% were provided at the expense of precipitation, and 50.9% at the expense of soil moisture reserves (Figure 3). The application of irrigation at 100 m³/ha reduced the share of soil moisture to 18.7%, and precipitation provided 44.8% of total water consumption. Increasing the irrigation rate to 200 m³/ha increased the share of irrigation water to 40.5% due to less soil moisture and precipitation.
Over the years of research, the average yield of early potato without irrigation was 10.44 t/ha. Humidification conditions significantly affected the yield of young tubers -watering at 200 m³/ha provided 21.61 t/ha, reducing the watering rate to Raisa Vozhehova et al. 8 100 m³/ha led to a reduction 19.86 t/ha. However, it should be noted that, compared with the option without irrigation, the yield increased by 51.3%.
At the same time, the lowest yield -9.68 t/ha was recorded in the variant with the treatment with the Mochevyn K complex without irrigation. Plantafol treatment of planting tubers and the treatment of plants during germination and budding without watering provided almost the same yield. The second and the third treatments of plants and tubers did not lead to a significant yield increase. The highest productivity of potato was provided by the treatment of tubers with Plantafol and the combination of tuber treatments and plant treatments during germination with a 200 m³/ha irrigation rate -on average for two years, 24.16 and 23.22 t/ha, respectively ( Figure 4). It is known that the density of the relationship between the studied factors and the level of yield is estimated by the absolute value of the correlation coefficient ( Figure 5).
The results of the correlation-regression analysis indicate a strong positive relationship (r = 0.95, 0.87 and 0.91) in all variants of the experiment. The coefficient of determination showed that the share of the total variation of potato yield was determined by the studied factors (R2 = 0.91, 0.75 and 0.81). In addition, 91%, 75% and 81% of the total fluctuations in potato yield were caused by differences in nutrition and moisture, and the remaining 9%, 25% and 19% -by other factors, which were not taken into account. Given the strong degree of connection (R² = 0.91) and the variable dependence (r = 0.95) between the crop and the studied factors, we had two negative coefficients in the calculated equations of the correlation-regression dependence on the options without irrigation and with the іrrigation rate of 100 m 3 /ha. This indicates an acute shortage of moisture and a significant shortage of crops in options without irrigation. Due to the treatment of tubers before planting and feeding with Plantafol without irrigation, a slight increase in yield was observed. With the increase of moisture supply by 100 m 3 /ha, we observed a significant increase in yield compared to non-irrigated variants, but the trend of the impact of treatment of tubers and plants with macro-and micronutrients on this indicator has not changed. In the equation describing the conditions of sufficient water supply (replenishment of moisture deficit by 200 m 3 /ha), a negative coefficient indicates that the second treatment of tubers and plants with Plantafol at the sprouting phase and the budding phase contributed only to a slight increase in yield compared to control without micronutrients.
According to the yield capacity, there was a difference in the efficiency of moisture and irrigation water use (Table 3).
The water consumption coefficient was 194-169 m³/t of tubers in the variants without irrigation. Its maximum value (194 m 3 /t) was recorded in the variant with the use of the treatment with the Mochevyn K complex. The yield herewith was the lowest in the experiment and amounted to 9.68 t/ha, which is 2.6% less than in control. The treatment with Plantafol at sprouting and the budding phase in nonirrigated conditions provided an increase in yield by 11.8%, and reduction of water consumption by 20 m³/t or 10.6%, compared with the control. The use of irrigation reduced this indicator to 92-119 m³/ha. At the same time, one cubic meter of irrigation water provided 20.7-29.1 kg of tubers. Moisture was best used with applying the irrigation norm of 200 m³/ha and the treatment of tubers with Plantafol -water consumption ratio of 92 m³/t and the maximum yield in the experiment -24.16 t/ha, which exceeded the control indicator (without treatment, with watering -200 m 3 /ha) by 29.4%. Irrigation water was used most economically when applying an irrigation norm of 100 m³/ha and foliar feeding with Plantafol at the budding phase -1 cubic meter provided 29.1 kg of tubers, The efficiency of different moisture and nutrition conditions in potato under drip irrigation 11 with a water consumption ratio of 95 m³/t; the yield exceeded the control indicator (without treatment) by 4.07 t/ha or 22.9%.
The calculation of economic efficiency has shown that growing young potato without irrigation provides 8.05-15.41K UAH/ha of conditional net profit and 15-35% of profitability (Table 4). The use of irrigation increases production costs in the variant with an irrigation rate of 100 m 3 /ha by 0.57-9.3K UAH/ha, with 200 m 3 /ha by 2.44-11.39K UAH/ha. However, the cost of potato decreased through increased yields. The net profit increases to 47.08-67.21K UAH/ha and 51.01-77.56, respectively, which provides the profitability of 93.2-127.4% with 100 m 3 /ha and 98.7-140% at 200 m 3 /ha.
The best economic indicators were formed with the Plantafol N 10 P 54 K 10 treatment at a norm of 1 kg/t with an irrigation rate of 200 m³/ha: production costs were 55.32 K/ha. The cost of potato in this variant was the lowest and amounted to 2.29 K UAH/t, and the highest conditional net profit was 77.56 K UAH/ha and profitability of production -140.0%.
In different climatic zones, scientists from different countries studied the influence of plant nutrition on the growth, development and yield of potato using the pre-planting treatment of tubers and foliar feeding. Thus, in Belarus, with the use of complex fertilizers and the growth regulator Phenomenelan, they managed to increase yields by 2.6-4.9 t/ha, while improving the quality of tubers. The foliar fertilization of the potato variety Zhukovskaya early by Kristalon brown in the budding phase caused an increase in yield capacity 2.8 t/ha in the Kursk region of Russia. The results of research in Ukraine (Sydorchuk and Kalitsky, 2009;Molotsʹkyy et al., 2009;Mʺyalkovsʹkyy, 2018;), and in Europe ( Van der Saag, 1993;Pomykalska, 1988;Burakov, 2007) indicate that the application of micronutrients for foliar feeding of potato plants helps to increase the yield and quality of tubers. However, with the advent of new forms of preparations of different composition, there is a need to study them in the technology of potato growing (Button and Hawkins, 1958;Laughlin, 1962;Kuisma, 1989;Haider et al., 2012;Jasim et al., 2013;Noaema et al., 2016).
Irrigation creates conditions for the full return of fertilizers, and those, in turn, increase the efficiency of irrigation. For example, according to the results of longterm studies in Moldova, the increase in the yield of tubers from fertilization without irrigation was only 3 centners/ha, against the background of irrigation -25, from irrigation without fertilizers -82, from the combined action of fertilizers and irrigation -10,7 t/ha .
Fertigation, or the application of fertilizers with irrigation water, helps to solve the problem of providing nitrogen, potassium, phosphorus and other elements (Potato grower, 2010). According to research, the effectiveness of applying fertilizers locally during planting and using irrigation water during the growing season is almost the same. The use of fertilizers in this way involves the use of fully soluble or liquid forms. As for the introduction of fertilizers into the soil, their dose is prescribed based on the presence of nutrients in the soil according to the results of the analyses. Feeding is carried out before flowering. Specialized fertilizers for drip irrigation or filtered extracts of combined fertilizers are used (Pisarenko, 2003). The use of this method of watering in the cultivation of crops allowed increasing yields by 30-50% while saving irrigation water by 3-5 times, mineral fertilizers by 20-40%, energy resources by 50-70%, etc. (Karmanov, 1964;Molyanov and Moiseev, 2003;Koryunenko and Matviyetsʹ, 2004). Based on many years of research, the positive effect of drip irrigation on potato yield has been proven (Ivenin et al., 2012;Shuravilin et al., 2013).

Conclusion
The study of the influence of moisture and nutrition conditions on seed potato growing using drip irrigation showed that the maximum yield -24.16 t/ha was obtained by treating potato tubers with Plantafol N 10 P 54 K 10 at a norm of 1 kg/t and replenishing the deficit of water consumption by 200 m³/ha. The best use of moisture was recorded -the water consumption coefficient was 92 m³/t, and the lowest cost of potato was 2.29 K UAH/t. The highest conditional net profit was 77.56 K UAH/ha and profitability of production -140.0%.