Yield and nutritional efficiency of corn in response to rates and splits of nitrogen fertilization

Resumo

Despite its relevance, nitrogen is poorly utilized by the plants when improperly applied. Thus, the objective of this
study was to evaluate the yield and nitrogen use efficiency (NUE) in corn in response to doses and split application of
nitrogen fertilization. The experimental design was a randomized block design, with three replications. Doses of nitrogen
of 0, 30, 60 and 180 kg ha-1 were applied at sowing in order to create different nutritional status of corn plants and to
obtain different values of Normalized Difference Vegetation Index (NDVI) measured with “Greenseeker®” optical sensor.
The subplots with nitrogen doses in topdressing of 0, 30, 60 and 90 kg ha-1 at V8 and a dose of 60 kg ha-1 at V12 were
placed in experimental plots with doses of 0, 30, 60 and 180 kg ha-1 of nitrogen at sowing. Moreover, NUE was calculated
in the experiment using agronomic indexes determined by applications of nitrogen in late topdressing (V8 and V12) and
contrasted to the possible combinations at doses of 60, 90 and 120 kg ha-1 of total N applied. The results showed the
occurrence of a linear relationship between nitrogen fertilizer dose and NDVI at V8 as well as at V12 stages. Late
topdressing fertilizations (V12) did not cause a decrease in grain yield when combined with nitrogen fertilization at
sowing, moreover resulted in higher NUE. Split the nitrogen dose showed better NUE than the combinations where
nitrogen was not applied at sowing or in topdressing. The delay of nitrogen topdressing can be an alternative for the
planning of the moment of the N fertilization according to the climate forecast in each region.