Principles of application
UAN can be used as a basal and side/top dress fertilizer under vegetative plants. Nitrate form of nitrogen is absorbed by growing plants immediately, ammonium form of nitrogen is fixed by the soil adsorption complex, amid form turns to ammonium and then to nitrate form. UAN is fast acting fertilizer with prolonged action.
Fertilizer is applied as the basal one while ploughing, subsurface tillage, cultivation to the depth of 5 cm or more and it can be sprayed on the surface with the help of sprayers with its further incorporation into the soil. Soil texture does not influence the depth of application, but it is needed to understand that light soil requires deeper application of fertilizer. Low nitrogen costs do not correlate to the depth of application. UAN can be used for stubble and vegetation processing after harvesting as the basal fertilizer for bacterial nitrogen nutrition when plant residues.
UAN side dressing can be applied with the help of inter-row processing aggregates or sprayers. Winter cereal and industrial crops can be side dressed with the help of sprayers. In the early spring at low temperatures foliar feeding with UAN can be used under growing plants with drop nozzles in order to prevent leaf burn even without water diluting. With temperature increasing and active vegetative resumption it is required to dilute solution by adding water, concentration ratio should be 1:2-4 to avoid leaf burn. With plants growth, side dressing is to be applied with sprayer machine with the help of hose to provide fertilizer spreading directly on the soil surface avoiding its falling on leaf. Winter cereal crops can be side dressed simultaneously with the use of zero tillage, but it is required to dilute solution by adding water in ratio 1:4-5 in no higher dose than 30 kg/ha of nitrogen active ingredient, amount of working solution of 250-300 l/ha at the temperature of 16-18 degrees. It is not recommended to use UAN under growing plants to prevent leaf burn when air temperature is more than 20 degrees, air humidity is low and weather is sunny. One of the limiting factors of UAN top dressing is downy mildew in the early hours and after rain that can cause leaf burns regardless the size of drop. Nitrogen application in form of UAN on dry soil does not solve problems with nitrogen supply, which is fixed by soil colloids and humidity. Fertilizer effectiveness increases when the soil is humid.