The research was conducted during 2019–2020 in the laboratory of agrochemical research and product quality of the Institute of Vegetable and Melon NAAS. The soil of the experimental site - typical low-humus loamy chernozem on loess loam (in the plow layer (0-25 cm) of humus contained 4.3%N hydrolyzed - 139,0 mg/kg, mobile P - 106-119 mg/kg and exchangeable K - 93 mg/kg of soil, hydrolytic acidity - 2.8 mg-Eq per 100 g of soil, pH of salt extract - 5.7, the sum of absorbed bases - 26.0 mg-Eq per 100 g of soil). The research studied the effectiveness of different fertilizing systems: 1) without fertilizer (control); 2) N185P185K225; 3) N370P370K450; 4) N370P370K450 + foliar fertilization with complex fertilizer "Nutrivant plus universal" 2 kg / ha in 3 terms; 5) mold 20 t/ha + ash 1 t/ha 6) mold 20 t/ha + ash 1 t/ha + tillage planting soil fertilizer "Hraundfiks" (3 l/ha) + the first fertigation microbial drug " Azotophyte ”(1 l/ha) + for the second fertigation microbial preparation“ Organic Balance ”(1 l/ha) + foliar fertilization“ Help-rost for vegetable plants ”2 l/ha in 3 terms. Foliar fertilization was carried out in three terms: 30 days after planting (III decade of June), with active growth of vegetative mass (III decade of July), with active growth of tubers (III decade of August). The research was conducted in accordance with generally accepted methods. The total area of the plot was 33.6 m2, accounting - 21 m2, repetition - three times. In the study, sweet potatoes of the Slobozhansky Ruby variety were grown under drip irrigation, planting schemes (100 + 40) x 25 cm and mulching the soil with straw. According to the results of the study, it was found that the use of mineral and organic fertilizers by improving the nutritional conditions of plants provided an increase in the yield of sweet potato tubers and had a positive effect on their biochemical properties. On average, over the years of research, the use of different fertilizer systems causes an increase in the total yield of tubers by 5.3–8.7 t / ha or 34–56%, the yield of standard tubers - by 2.9–4.6 t / ha or 27–42 %. The highest level of sweet potato yield was provided by the use of N370P370K450 in combination with Nutrivant plus universal foliar fertilizers. The total yield of such a fertilizer system is 24.3 t / ha, of which 15.5 t / ha of standard tubers. According to our data, the effectiveness of increasing the dose of mineral fertilizers from N185P185K225 to N370P370K450 has not been proven, as there is no significant difference between the options. Additional fertilization with complex fertilizers provides a positive trend to increase the yield of sweet potatoes by 3.3 t/ha. The use of an organic fertilizer system (20 t / ha of humus and 1 t / ha of ash) provides an increase in the total yield of tubers by 6.7 t / ha or 43%, while the additional use of a set of microbial drugs is not justified by a significant increase in yield (22.8 t / ha). It was found that the use of organic fertilizers in combination with microbial preparations had the most positive effect on the biochemical composition of sweet potato tubers. Under this system of nutrition optimization, the dry matter content in tubers (18.6%), starch (9.06%) increased, and the low nitrate content (28.1 mg / kg) was noted. Under the mineral fertilizer system N370P370K450 with the use of complex fertilizers significantly increased the dry matter content (17.7%), however, the nitrate content was the highest in the experiment (78.5 mg / kg). There is a tendency to reduce the total sugar in sweet potato tubers with the use of all fertilizer systems, especially with the use of mineral fertilizer system N370P370K450 in combination with foliar fertilization "Nutrivant plus universal" (3.4% with the value of this indicator in control - 4.74%). To adjust the doses of mineral fertilizers under sweet potatoes, we calculated the absorption coefficients of nutrients from fertilizers and soil. It was found that on chernozem, a typical low-humus light loam plant, sweet potatoes absorb up to 57% of mobile forms of N, 11.6% of mobile forms of P and up to 61.2% of mobile forms of K. Nutrient utilization factors from mineral fertilizers are 40.7% for N; P - 26.1%, K - 73.5%. It should be noted that the utilization rates of soil nutrients vary not only depending on the biological characteristics of plants, but also due to changes in soil fertility, weather conditions, level of technological support, etc., which to some extent complicates their use in determining estimated doses of fertilizers. The rate of absorption of nutrients by sweet potato plants under different fertilizer systems was established. Without fertilizers, sweet potato plants absorb 88.2% N, 60.6% P and 80.5% K from the total consumption of plant nutrients in the first two months of growth. With mineral and organic fertilizer systems, the peak of nutrient consumption occurs at 2-3 months of plant growth, ie with the active formation and growth of tuber mass. Without the use of fertilizers by the end of the growing season significantly reduced uptake by plants P (104.4 kg/ha) and K (252.4 kg/ha), which, in our opinion, affect the reduction in yield yam. It should be noted that the uptake of K by sweet potato plants in the Forest-Steppe of Ukraine is higher than in the soils of the southern regions (according to Degras [34], the removal of K with sweet potato plants is 110–135 kg/ha). It is noted that depending on the fertilizer system 56.9–76.9% of N accumulates in the leaves, 10.2–13.6% in the stems, 12.9–29.5% in the roots and tubers. P 31.2–49.9% accumulates in leaves, 13.4–20% in stems, 30.1–55.4% in roots and tubers; for K 41.6–51.9% in leaves, 13.2–21.2% in stems, 26.9–45.2% in tubers and roots.
HAMA PENTING TANAMAN UBI JALAR (Ipomea batatas L.(Lamb)) DI KABUPATEN MINAHASA, MINAHASA UTARA, DAN KOTA TOMOHON
