Abstract

DA ROS, Clovis Orlando; SALET, Roberto Luiz; PORN, Rodrigo Luiz  and  MACHADO, Josemar Nerí Corrêa. Effects of fertilization methods on soil nitrogen availability for wheat and corn production. Cienc. Rural [online]. 2003, vol.33, n.5, pp. 799-804. ISSN 0103-8478.  http://dx.doi.org/10.1590/S0103-84782003000500002.

The aim of this experiment was to evaluate the N availability for corn and wheat with different methods of N fertilization. The study was carried out at University of Cruz Alta, State of Rio Grande do Sul, Brazil, in an Oxissol under six years of no-tillage. A completely randomized block design with four repetitions was used. Combinations of different times and rates of N application were studied. The times were: application before seeding, at seeding and topdressing. The rates of N for corn were zero, 60 and 90kg ha^-1 and for wheat zero, 30 and 60kg ha^-1. The amount of soil mineral N decreased quickly after application of N fertilization. The soil´s mineral N content was related to the rates and time of application. The N application time, considering the same rates, splitted or not, didn't influence dry matter production, N accumulation and grain yield. These parameters increase with the rate of N application. The splitting of the N fertilization, part at the seeding time and part as topdressing, is the safest way to minimize the N losses and to maximize the use of N by corn and wheat plants.

Keywords : mineral nitrogen; nitrogen rates and application time.