Ammonium nitrogen regimen of leached chernozem in stationary experiment with fertilizers and defecate

The regimen of ammonium nitrogen of leached low-humic moderately deep heavy loam chernozem was studied in 2019-2022 in a stationary experiment with fertilizers and defecate of the Department of Agrochemistry, Soil Science and Agroecology of the Voronezh State Agrarian University. The experiment was established in four-fold repetition, plot area - 200 m2. Alternation of crops in crop rotation – fallow, winter wheat, sugar beet, vetch-oats mixture, winter wheat, barley. The analysis of soil samples was performed using ion-selective electrodes made by Volta in water-saturated pastes at a soil:solution ratio of 1:0.5. Exchange ammonium was determined by photocolorimetric method with Nesler reagent. It has been established that organic and organomineral fertilizer systems contribute to an increase in the water-soluble content and exchange-absorbed forms of ammonium nitrogen; the content of the latter in the studied soil is significantly higher. The use of ameliorator reduces the content of water-soluble and exchange-absorbed ammonium, yet it stabilizes all types of soil acidity. The distribution pattern of NH4+ is predominantly eluvial-illuvial and is practically the same for both the water-soluble and the exchange form. The correlation of exchange-absorbed ammonium content with the acidity of the soil was determined. On the control and fertilized options, the interrelation of exchange-absorbed ammonium content with the pH value of the aqueous and salt extract was negative, medium and close; on the options with defecate - positive, medium and close; with the value of hydrolytic acidity in the control and fertilized options - mainly medium and close, in the options with defecate - ranges from medium to close in separate years.