**2.7. N use efficiency**

For the assessment of N use efficiencies, the following parameters were defined (Huggins and Pan, 1993):

Efficiency in the use of the fertilizer (NUE): difference between Nab of the fertilized treatment and the non-fertilized, divided by the quantity of fertilizer applied.

Harvest index (HI): quotient between the N in the grain and the N extracted by the aerial part of the culture (dimensionless).
