Redox potential change of light grey forest surface-gleyed soils depending on the long-term anthropogenic impact

Abstract

Influence of prolonged application of various fertilizer systems and periodic liming on the dynamics of redox potential (ROP) of light grey forest surface-gleyed soils under different crop rotations is presented in the research results. The obtained ROP indexes showed significant variability in variants of experiment depending on the fertilizer, lime and terms of determination in both fields of winter wheat and spring barley. The highest ROP values in variants with organo-mineral and mineral fertilizer systems with background of liming were observed in spring. They decreased during the period of maximum growth and development of winter wheat and spring barley together with the growth of microbiological activity and the intensity of CO2 release, and slightly increased before harvesting. It was established that the application of organo-mineral and mineral fertilizer systems with the background of liming with CaCO3 dose, calculated according to hydrolytic acidity, to the greatest extent increase ROP, especially during the period of intensive growth and development of plants. Compared to similar fertilizer system with the background of liming with a CaCO3 dose, calculated according to the pH- buffer capacity, it contributes to one-sided growth of oxidation processes and additional mineralization of humus. Thus, the organo-mineral fertilizer system with the application of 10 tons of manure per hectare of crop rotation and one norm of mineral fertilizers (N65P68K68) with the background of liming with CaCO3 dose, calculated according to the pH-buffer capacity (2.5 t/ha), contributes to rational use, preservation and fertility protection of light grey forest surface-gleyed soils, optimizing the redox potential during whole growing season of crops, and provides high yields. Studies have shown that during whole growing season of winter wheat and spring barley the lowest values of oxidation were obtained with the long-term use (for 50 years) of mineral fertilizer system with the introduction of one norm of mineral fertilizers only. It led to a decrease in the actual soil acidity to 4,03 pHKCl units and the increase of hydrolytic acidity to 5.11 mg-eq/100 g of soil. This once again emphasizes the importance of periodic liming of acid light grey forest surface-gleyed soils as a factor weakening the negative influence of mineral fertilizers. Key words: light grey forest surface-gleyed soils, redox potential, mineral fertilizers, manure, lime.