The relationship between nitrogen fertilizer forms and meteorological conditions on nitrogen transformation in the soil and loss via volatilization

The study was aimed to estimate the changes in ammonium (N-NH 4 + ), nitrate (N-NO 3 -) and mineral (N-NH 4 + + N-NO 3 -) nitrogen in the soil, nitrogen loss via volatilization and uptake as influenced by the nitrogen fertilizer form applied, soil moisture and temperature in the crop stand of the common wheat (Triticum aestivum L.) cultivar 'Skagen' during the tillering stage .The crop was fertilized with surface-broadcast urea and ammonium nitrate (granular fertilizers).The soil of the experimental site is Endocalcaric Endogleyic Luvisol (WRB, 2014).The content of N-NH 4 + in the soil 7 days after winter wheat fertilization was found to be on average 25% higher in the plots applied with urea, while higher N-NO 3 -and N-NH 4 + + N-NO 3 -contents, by 59% and 29%, respectively, were identified in the ammonium nitrate-applied plots.When winter wheat had been applied with ammonium nitrate or urea 4 days after resumption of spring growth, the contents of N-NH 4 + , N-NO 3 -and N-NH 4 + + N-NO 3 in the soil were significantly higher compared with the plots fertilized later, 8-16 days after beginning of spring growth.At winter wheat tillering stage, the content of N-NH 4 + + N-NO 3 -in the soil was found to depend on soil temperature and moisture.The data of the multiple correlation analysis showed a strong relationship between N-NH 4 + + N-NO 3 -content and soil temperature and moisture, significant at P < 0.05 level, in the winter wheat plots applied with ammonium nitrate (R 2 = 0.719) or urea (R 2 = 0.879).Volatilization of N-NH 3 in the winter wheat plots fertilized with ammonium nitrate was negligible and totalled 0.24%, while in the plots applied with urea it averaged 7.3%.Volatilization of N-NH 3 from urea depended on the soil temperature and moisture (R 2 = 0.840, P < 0.05).In the plots fertilized with ammonium nitrate, the concentration of nitrogen in the above-ground part of winter wheat was higher, though not in all the treatments significantly, as compared with the urea-applied plots.