Α Dynamics of Macro Elements Content in Eutric Podzoluvisols for Separation of Wastewater under Jerusalem Artichokes

Abstract

The application of fertilizers based on sewage sludge significantly affects the formation of the nitrogen fund of sod-podzolic soil, as well as changes in the content of mobile compounds of phosphorus and potassium exchange. The application of such fertilizer under Jerusalem artichoke has a positive effect on the nitrogen content of alkaline hydrolyzed compounds, in particular on increasing the content of mineral and alkaline hydrolyzed nitrogen fractions. The application of sewage sludge at a dose of 20–40 t/ha and the appropriate compensatory dose of mineral fertilizers at the rate of N90P90K90 helps to increase the content of ammonium nitrogen compounds from 16 to 20–22 mg/kg of soil in the upper (0–20 cm) layer – 28% prevails over the control variant, as well as the content of nitrate nitrogen compounds in the layer 0–40 cm from 1.70 to 2.52–2.64 mg/kg of soil. The ratio of the content of alkaline hydrolyzed nitrogen compounds to the nitrogen content of mineral compounds in the experimental conditions changes insignificantly, which indirectly indicates a relatively stable value of this indicator, which changes little under the influence of fertilizers. The application of sewage sludge as a fertilizer significantly affects the change in the content of mobile phosphorus compounds and potassium exchange compounds in the upper (0–40 cm) layer of the soil. However, from a depth of 60 cm, their content decreases sharply and approaches the initial values of the control version. Depending on the application of fertilizers, the indicators of the coefficient of concentration of macronutrients in the soil change significantly, which reflects the ratio of the content of the element in the soil to its content in the control variant. As the rate of sewage sludge increases, the element concentration coefficient increases from 1.27 in the variant with the application of only mineral fertilizers to 2.36 for potassium and for phosphorus – from 1.02 to 1.31. There is a close correlation between the content of phosphorus and potassium in the soil and the coefficients of their concentration. This relationship reflects the multiple coefficient of determination, which for phosphorus and potassium is R2 = 0.69 and R2 = 0.90, respectively. The use of fertilizers in the form of compost with sewage sludge and straw of cereals causes similar trends as the introduction of uncomposted sewage sludge. However, this effect has less radical impact with lower absolute nutrient content compared to the introduction of fresh sewage sludge. The application of sewage sludge in the form of compost and uncomposted form contributes to a significant increase in the content of macronutrients in the soil, providing an improvement in the mineral nutrition of cultivated plants, including Jerusalem artichokes.