The Effects of Soil Supplementation with Different Nitrogen Fertilizers on Select Fertilization Indices in Two Types of Maize Hybrids (Zea mays L.) and on Mineral Nitrogen (Nmin) Contents in Soil

This paper presents the effects of soil supplementation with different forms of nitrogen fertilizers on select fertilization efficiency indices in two types of maize hybrids and on changes in contents of mineral nitrogen in soil after maize harvest. Nitrogen content in grain of maize and its uptake with grain yield and utilization were significantly higher for slow-release fertilizers in comparison to quick-release nitrogen fertilizers. The application of 25 kg MgO.ha(-1) significantly increased nitrogen uptake with grain yield and its utilization in comparison to the object with no application of this macronutrient. Better indices of nitrogen use efficiency were recorded for the stay-green hybrid cv. ES Paroli in comparison to the traditional cv. ES Palazzo. Irrespective of the tested experimental factors, the percentage of nitrogen absorbed from the fertilizer in the total amount of nitrogen uptake was less than 25%. The advantage of the stay-green hybrid in comparison to the traditional cultivar in terms of nitrogen content in grain, the uptake of nitrogen with grain yield, and utilization of nitrogen were significantly higher for slow-release nitrogen fertilizers. The combined application of ammonium sulphate in fertilization with 25 kg MgO.ha(-1) caused a negative increment in nitrogen uptake and utilization in relation to other nitrogen fertilizers. Significantly less mineral nitrogen (N-min) in soil after maize harvest was detected in objects on which slow-release fertilizers (e.g. ammonium sulphate and urea) were used in comparison to quick-release fertilizers (e.g. ammonium nitrate). The application of 25 kg MgO.ha(-1) in comparison to the object, where this macronutrient was not used, is a cultivation measure causing lower burden of this biogen for the natural environment. The stay-green hybrid ES Paroli in relation to cv. ES Palazzo reduced nitrogen eutrophication of the natural environment with mineral nitrogen. Only nitrate nitrogen was highly correlated with total mineral nitrogen in soil at each depth of soil sample collection. The use of nitrogen fertilizers caused an increase in the contents of nitrate nitrogen in the total amount of mineral nitrogen in the 0-30 cm and 30-60 cm soil profiles. In turn, the application of magnesium and the stay-green cultivar reduced the amount of N-NO3 in the total amount of N-min in the period after the maize harvest.