The Effects of Side-Dressing Different Rates and Release Types of Nitrogen Fertilizer on Hybrid Seed Maize Production

Chemical fertilizers have been for a long time similar to the original ones created in the 1960’s, only recently with the increase emphasis on environmental impact, and the need to reduce quantities of fertilizers used, we have seen the introduction of slow-release and controlled release fertilizers from small surface high value crops towards large field crop production. Side-dressing N fertilizers in maize crops has been a standard in Europe for more than 50 years and thus still has a wide rate of adoption in farms, as it has been the easiest option to apply nitrogen closer to the maximum consumption point, which starts after the plant reaches 8 leaves stage (BBCH-18). Thus, our research has focused on studying the impact of using different rates of nitrogen (40, 80 and 120 kg/ha) of the new release types of fertilizers (Urea NG, Multicote 34-0-7) side-dressing and to establish if there is any benefit, in hybrid seed maize production, of substituting classical fertilizers (ammonium nitrate) with newer ones. The study has been conducted for 3 years in irrigated field research plots in the soil and climatic conditions from north-east of Romania. Our research has revealed several key aspects in terms of the effect on vegetative and generative development of hybrid seed maize plants: longer vegetation period for plants fertilized with slow and controlled release fertilizers, better use of the nitrogen from classical fertilizers as their availability for uptake overlaps with the needs of the plant starting from the side-dress moment. Other aspects evidentiated are reduction in quantity of fertilizer needed, thus economic benefits and similar yield with classical nitrogen fertilizer dressing.