CHANGES IN SOIL AGROCHEMICAL PARAMETERS ACROSS WINTER RYE GROWTH PHASES DEPENDING ON THE USE OF MINERAL FERTILIZERS

This paper presents the results of research assessing the impact of mineral fertilizers on the main agrochemical parameters of sod-podzolic heavy loamy soils during winter rye growth stages. The studies were conducted in Perm district of Perm region in 2019 and 2021 as part of a long-term stationary experiment. The sample from full experimental scheme consisted of variants with increasing doses of nitrogen fertilizers against three phosphorus-potassium backgrounds. The soil in the experiment before sowing winter rye had a moderately acidic and slightly acidic pH, high and very high content of available phosphorus, and elevated and high content of exchangeable potassium. By the heading phase of winter rye, there was a reliable decrease in pHKCl by 0.2 pH units on average for all the studied variants (LSD05=0.1). The greatest decrease was observed with the use of N120P30K30 and N150P60K60 and amounted to 0.3 pH units (LSD05=0.2). A tendency to decrease the mobile phosphorus content between phases was established in the control variant and with the use of N90 by 13 and 32 mg/kg. The content of available potassium increased by the heading phase, primarily due to a change in the indicator in the variants using N60P60K60 and N150P60K60 by 39 and 38 mg/kg, respectively (LSD05=27 mg/kg). The ammonium nitrogen content significantly increased by 7.3 mg/kg by the heading phase (LSD05=5.9 mg/kg). The nitrate nitrogen content tended to decrease by 8.6 mg/kg. Grain productivity significantly and moderately correlated with the mobile phosphorus content in both studied phases (r=0.42 for both phases) and the ammonium nitrogen content at the heading phase (r=0.45).