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The purpose of research is to establish the dependence of the applied doses of mineral fertilizers on the symbiotic activity of soybean crops in the foothill zone of the Republic of North Ossetia – Alania. Objectives: to establish optimal doses of mineral fertilizers that have a positive effect on the symbiotic activity of soybean crops. Field experiments were carried out in the forest-steppe zone of the Republic of North Ossetia – Alania, on lands belonging to the North Caucasus Research Institute of Mountain Foothill Agriculture of the All-Russian Scientific Center of the Russian Academy of Sciences. The soils of this zone are represented by leached chernozems; the mechanical composition of the upper horizons of the soils under consideration is heavy loamy, silty-dusty. With depth in the profile it becomes lighter and becomes medium loamy. Chernozems leached on pebbles have a good water-resistant structure. The gross humus content is in the range of 1.56–6.30 % depending on the soil section, pH – 5.1–5.7, deeper alkaline. The objects of the study are soybean varieties Iriston and Vita. Iriston is a variety selected by IrAgro LLC, Vita is a variety selected by V.S. Pustovoit All-Russian Research Institute of Oil crops. The use of various doses of fertilezers increased the number and weight of nodules; with the use of phosphorus-mineral fertilizers, better development of the symbiotic apparatus was observed. The average ASP for the studied years for the soybean variety Iriston in the control variant was 5 425 units, and with the application of phosphorus mine¬ral fertilizers (P60) it was within 11 890 units.For the Vita variety, similar indicators developed and amounted to 3 800 in the control, with the application of P60 – 7 816 units, 4 016 units more. Nitrogen consumption under control for the Iriston variety was 92.5 kg/ha, with the use of phosphorus fertile¬zer (P60) – 131.3 kg/ha. Biological productivity also increased with the use of phosphorus fertilizers for the Iriston variety by 0.57 t/ha, and for the Vita soybean variety – by 0.54 t/ha.
Tadeeva et al. (Tue,) studied this question.