Comparing application methods for N-fertilizer in the sugar beet crop (Beta vulgaris L. subsp. vulgaris).

BACKGROUND. Sugar beet seeders have been developed in other countries, in order to place nitrogen into the soil at a few centimeters from the seed. Placing fertilizer has proved safe for seedling emergence, successful in reducing soil residual nitrogen at harvest, sometimes even better-yielding than broadcast applications. METHODS. In a 3-year research on sugar beet, spreading fertilizer on the soil surface followed by incorporation was compared with placing in rows 6 and 3 cm far from the seed ones, slightly deeper than the seed, in combination with two rates of urea-N, 60 and 120 kg ha-1, plus an unfertilized check. The course of soil mineral nitrogen and that of N-uptake were evaluated during crop cycle. Yield and quality were evaluated at harvest. RESULTS. Nitrogen placement close to the seed (3 cm) negatively affected crop emergence. In the plant-soil system, placement showed a higher soil N-content in the first phases and a lower plant uptake at harvest. As for yield, placement attained a slightly-lower level than broadcasting at 60 kg N ha-1 of N, almost the same at 120. No significant difference in quality was observed between the two patterns. CONCLUSIONS. At a certain distance from the seed, placement proved a safe way of applying fertilizer. Its yield and quality, the uptake by the plant and the amount of soil residual-N are comparable with those of broadcast fertilizer; in the case of soil nitrogen, it is perceived that the year/location effect is potentially stronger than that of rate/pattern of application.