Application of mineral fertilizers on ordinary chernozem soil in the rotational link of field grain-fallow crop rotation

The research was carried out in field crop rotation to improve the use of mineral fertilizers in the cultivation of spring wheat, peas and flax under the conditions of North Kazakhstan. The aim of the research was to study the impact of the use of mineral fertilizers on the yield of crops in the rotational link of eight-field grain-fallow crop rotation. Field experiments were carried out in 2015-2017 on ordinary chernozem in the Kostanay Region. The availability of nitrate nitrogen in the 0-40 cm layer (N-NO3 content of 11.2 mg/kg) and of movable phosphorus in the 0-20 cm layer (Р2О5 80 mg/kg, according to Chirikov) were average, the availability of exchange potassium (К2О - 420 mg/kg, according to Chirikov) was high, the humus content amounted to 5.4%, the pH (aqueousr) was 6.6-7.0. It has been found that the highest degree of plant availability of nitrate nitrogen at the onset of the vegetation is observed in flax crops in case of zero cultivation technology in the N30 option (14.8 mg/kg of soil), as well as in wheat after peas in case of traditional and zero cultivation technologies (13.0 and 13.2 mg/kg of soil). The lowest content (5.9 mg/kg) is observed in pea and flax crops in case of traditional and zero cultivation technologies in fertilizer-free options. The content of mobile phosphorus in the soil after the sowing of crops in most test options is noted at the level of average availability (74.0-101, mg/kg of soil) and increased in case of application of N30P20. Both soil treatment systems show a tendency to have a positive effect of local fertilization on the field germination of wheat seeds. In case of traditional technology the maximum yield is noted in the N30P20 option when cultivating wheat after peas and amounts to 2.16 t/ha; the yield of peas amounts 2.0-2.21 t/ha, or 2.47-2.58 t/ha in case of zero cultivation technology. A weak positive reaction of peas to the application of nitrogen-phosphorus fertilizers and a negative reaction to nitrogen in pure form should be noted. The yield of flax amounted to 1.08-1.41 t/ha with traditional technology and 1.25-1.57 t/ha - with zero technology, the maximum yield was obtained against the background of N30 with zero soil treatment, which allowed to form an increase of 0.49 t/ha or 45.4% if compared to the control sample.