SOURCES AND NITROGEN RATES IN COVERAGE AT THE GRAIN SORGHUM IN THE INTERCROP SEASON

Nitrogen top dressing fertilization is an unusual practice in off-season grain sorghum so that theproduction of straw and grains of sorghum is done using residues of the fertilization of the summer crops. This studyobjectified to evaluate the response of off-season grain sorghum crop to doses and sources of nitrogen applied as topdressing. Treatments consisted of the combination of two nitrogen sources (urea and ammonium sulfate) and fivenitrogen doses (0, 20, 40, 60 and 80 kg.ha-1) applied at the panicle initiation stage (EC2). A randomized blocks designwas used in a 2 x 5 factorial scheme, with four replications. Plant height, culm diameter, grain number per panicle, plantdry matter, harvest index, weight of 100 grains and grain yield were evaluated. Ammonium sulfate increased plantheight. The hybrid evaluated showed a linear relation of plant dry matter and nitrogen top dressing. The ammoniumsulfate caused higher increase in dry matter yield compared to urea. A quadratic relationship between nitrogen topdressing and grain yield was observed, obtaining 3389.4 kg.ha-1 with 65.10 kg.ha-1 of top dress nitrogen.