Dynamics of microorganism in dark kastanozems in different systems of basic tillage and fertilizer in crop rotation on irrigation

The influence of the systems of basic tillage on the number of microorganisms for the cultivation of winter barley, corn for grain and soybean in irrigated crop rotation in the South of Ukraine was determined. Placement of variants of the experiment of basic tillage was carried out: plowing – plow PLN-5-35; chisel loosening – GRNF-4M and CHG-40-02; disk to a shallow depth (12‒16 cm) – heavy disk harrow BDVP-4.2; disk on surface (6‒8 cm) – light disk harrow BDLP-4 with soil rollers. Placement of variants in the experiment is systematic, repetition – four times, area of ​​sites – 450 m2. The control variant is the generally accepted system of multi-depth plowing to a depth of 20‒22 cm for winter barley and 28‒30 cm – for corn for grain. It was found that the beginning of the spring vegetation of winter barley with the background of N75R60 per 1 hectare of crop rotation area, the largest number of microorganisms (27.16 million pieces / g of absolutely dry soil) noted in the variant of multi-depth basic tillage with the rotation. In the case of plowing at one depth (12‒14 cm) the number of ammonifying microorganisms was the lowest compared to other systems of primary tillage and relatively to plowing (23‒25 cm) decreased by 12‒23%. Inoculation of soybean seeds with a bacterial substances ABM (bacteria of the genus Rhizobium, strains 201, 202, 203) with fertilizing of N60P60 in the period from the beginning of the vegetation and before harvesting, there was an increase in the number of microorganisms within from 7.0 to 15.5%, in the case of shallow plowing at one depth and in variants with differentiated tillage. Increasing the nitrogen doze from N75 to N97.5 provides for an increase in the number of microorganisms by 4.4% and contributes to the improvement of agrophysical properties, increases the levels of plant nutrition with mineral nutrients and moisture.