Adequacy of side dress nitrogen rates in corn based on soil and plant indicators

The objective of this work was to test one methodology to determine nitrogen (N) optimum rate to side dress at V6 corn stage, using soil and plant characteristics, and to verify which are the most precise indicators of N rate application. A field experiment was carried out in Eldorado do Sul, RS, Brazil, in two growing seasons. The treatments were five N rates applied in two timings. The following variables were measured: corn grain yield, leaf relative chlorophyll content, leaf and plant dry weight, N content and accumulated in the leaf, and plant and soil nitrate, ammonium and N mineral contents were measured at V6. From the evaluated characteristics, the most precise to predict optimum N rate for side dressing in corn were plant dry weight, N accumulated in the plant and leaf relative chlorophyll content. The results show that is possible to adapt or to develop a method to predict the optimum N rates for side dressing, using soil and plant characteristics, since there is a N response curve available from a group of experiments.