Ciobanu, GheorgheCiobanu, CorneliaDomuta, CornelCsep, NicolaeBurescu, Petru2021-06-282021-06-282002-05-12Acta Agraria Debreceniensis, No. 1 (2002): Special Issue - Journal of Agricultural Sciences , 41-462416-1640https://hdl.handle.net/2437/316997Nitrogen fertilizer represents major economic burden. For this reason, although the efficiency of nitrogen utilization varies highly, its actual use generally remains at low levels; these averaging between 25 and 50%. We set up an experiment at the Oradea Research Station, using 15N labeled fertilizers, in order to investigate the possibility of increasing N fertilizer efficiency in winter wheat under irrigation conditions. Fertilizers labeled with 15N allows us to individually determine its effect on yield formation, as well as the use efficiency of N from fertilizer following application rate and time. The amount of N derived from fertilizer as determined in straw and grain yield is high. When the labeled fertilizer is applied at tillering time, the values of this indicator rise when higher N levels we applied. In separate experiments, we investigated a series of aspects connected to chemical fertilizer regarding the determination of the type of fertilizer, optimum time and rates of application; all these as a function of the special pedoclimatic conditions. The results obtained in the field show that the effectiveness of N utilization in wheat is most variable and generally low, often ranging between 25 and 33%, owing to N loss within the system through leaching and NH3 volatilization. A readily achievable increase in efficiency of 5 percentage points would result in considerable savings, and can be brought about by reducing nitrogen losses. The added benefits to the environment in terms of reduced ground/water contamination and lowered nitrous oxide (N20) emissions would also be substantial. The figures for N fertilizer use efficiency (% N range from 35.5 to 72.6, the highest value being recorded with an N application of 120 kg/ha at tillering, when the previous crop was sunflower). INTRODUCTIONapplication/pdffolyóiratcikkOpen Accesshttps://doi.org/10.34101/actaagrar/1/3535Acta Agraria Debreceniensis1Acta agrar. Debr.