Biometric Relations, Physiological and Nutrient Accumulation of Maize Subjected to Sources and Levels of Nitrogen in the Brazilian Semiarid Region.

Biometric relations, physiological and nutrient accumulation of maize subjected to sources and levels of nitrogen in the Brazilian Semiarid region Modesto, V. C.1; Souza, H. A.2; Natale, W.3; Meyer, A. S.4 1Departamento de Fitossanidade, Engenharia Rural e Solos - Universidade Estadual Paulista/FEIS – Campus de Ilha Solteira – Brasil, e-mail: vivianemodesto@hotmail.com. 2 EMBRAPA/CNPC – Sobral – Brasil. 3 Departamento de Solos e Adubos - Universidade Estadual Paulista/Faculdade de Ciências Agrárias e Veterinárias – Campus Jaboticabal - Brasil. 4 Departamento de Ciências Exatas - Universidade Estadual Paulista/Faculdade de Ciências Agrárias e Veterinárias – Campus Jaboticabal – Brasil Abstract -The nitrogen fertilization is the agricultural practice that influences the most the grains yield in the maize culture. Together to the use of technologies the use of fertilizers promotes a better use of N by the cultures. This way, it was aimed evaluate the biometric characteristics, chlorophyll amount, biomass production, and the nutritional status of maize plants when submitted to different sources and doses of nitrogenous fertilizers. The experiment was carried out in a Luvisol, at Embrapa/CNPC Experimental Field in Sobral, CE, Brazil. The treatments were five nitrogen sources: urea + NBPT, urea + polymer, urea + enzymatic inhibitor, urea + sulfur covering, and urea without technology added. Three doses of nitrogen were used: 45, 67,5 and 90 kg N ha-1 and an additional treatment, without nitrogen fertilization, as top dressing 30 days after planting. The nitrogen fertilization combined to technology promoted higher chlorophyll contents and biomass production in the maize plants. The model that best fits the data was the quadratic, obtained with the estimated dose of 65 kg N ha-1 for both variables. The maximum agronomic economic efficiency was reached using urea without nitrogen fertilization, as top dressing 30 days after planting. The nitrogen fertilization combined to technology promoted higher chlorophyll contents and biomass production in the maize plants. The maximum agronomic economic efficiency was reached using urea without technology added, urea + urease inhibitor, and urea + elementary sulfur, corroborating the results obtained by Silva et al., (2011), in a study using urea, with and without fertilization combined to technology, in different doses, observed that urea without technology and urea + NBPT showed higher agronomic efficiency in corn. It can be concluded that the use of nitrogen fertilizers with fertilization combined to technology promotes a better crop yield.