50­річна динаміка вмісту рухомих сполук азоту, фосфору і калію в чорноземі опідзоленому за даними стаціонарного польового досліду

Abstract

Goal. To establish the regularities of dynamics of changes in the supply of basic nutrients at the systematic use of mineral fertilizers and after the cessation of their application. Methods. Statistical-mathematical analysis of observations on the content of mineral nitrogen, mobile phosphorus, and potassium in degraded chornozem of the stationary field experiment with fertilizers in 1970 -2020 on the territory of SE «SF Hrakivske» of NSC ISSA named after O.N. Sokolovskyi» (Kharkiv district, Kharkiv oblast). Results. Without the use of mineral fertilizers, the content of mineral nitrogen in the arable layer of the soil depends on the number of deposits and mostly corresponds to gradations of very low or low levels, and the content of mobile phosphorus and potassium corresponds to the limits of low and medium supply of these elements. With the systematic application of mineral fertilizers, the content of mobile phosphorus and potassium in the soil increases at the rate of 50 kg of the active substance (a.s.) per 1 ha with an intensity of 2.3 mg/kg per year and 1.2 mg/kg per year, at the rate of 100 kg a.s. per 1 ha — 3.1 mg/kg per year and 2.4 mg/kg per year, respectively. The consumption of phosphorus fertilizers to change the content of mobile P2O5 in the arable soil layer by 1 mg/kg depends on the duration of systematic fertilization and is 13.1-25.9 kg of P2O5 per 1 ha. The cost of potassium fertilizers to change the content of mobile K2O in the arable soil layer by 1 mg/kg is much higher than phosphorus and on average during the experiment was 49.5 kg a.s./ha. After the cessation of fertilizer application, there was a decrease in the content of mobile phosphorus in the soil in the first 10 years by 5.5 mg P2O5/kg per year, 20 years — by 4.8 mg P2O5/kg, for 30 years — by 4.1 mg P2O5/kg. The reduction of mobile potassium content in the soil after the cessation of fertilizer application is almost twice as fast as phosphorus. Conclusions. Using modeling of different levels of mobile phosphorus and potassium, the intensity of changes in the trophic state of the soil with the systematic application of mineral fertilizers under field crop rotation and after the cessation of fertilization. The estimated costs ic calculated of the active substance of phosphorus and potassium fertilizers to increase the content of mobile phosphorus and potassium by 1 mg/kg of soil, as well as the intensity of its reduction with extensive use of chornozem (without mineral fertilizers).