NITROGEN SIDEDRESSING AND MOLYBDENUM APPLICATION TO UNTILLED CORN AND NITROGEN (15N) ALLOCATION IN THE PLANT

Maize yield has increased with the development of modern cultivars and the demand for N has followed the same trend. The objective of this study was to evaluate the effect the timing of N application on grain yield and distribution in maize plant components in the presence and absence of Mo fertilizer under no-tillage. The experiment was conducted in the 2006107 growing season, at the Experimental Station of Coimbra-MG. The experiment was arranged in a randomized block with three replications in a factorial 3 x 2 + 1 design, with three N application dates, in the absence on presence of Mo fertilization, and an unfertilized control. The treatments consisted of: T1-total N applied 15 days before planting, without Mo, T2-total application of N at planting without Mo; T3-total N application at the stage of four completely developed leaves, without Mo; T4-total N application 15 days before planting, with Mo, T5-total application of N at planting, with Mo; T6-total N application at the stage of four completely developed leaves, with Mo, and T7-control without N application without Mo, applied to the come single hybrid AG 9010. Nitrogen supply throughout the cycle was best and yields were highest with fertilizer application at the four expanded leaves stage. No effect of Mo fertilizer was observed on the characteristics evaluated. Application of N prior to come sowing (15 days before planting) is not recommended for the climate and soil conditions studied. Most applied N was allocated in the grain. The average N-15 recovery from fertilizer in plants was 6 %.