AGROCHEMICAL EVOLUTION OF THE CHERNOZEMIC SOIL IN THE SUPERFICIAL HORIZON BY DIFFERENTIATED NITROGEN FERTILIZATION

1 University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Romania 2 Suceava Genebank, Romania ABSTRACT. Soil fertility, upon which plant growth and hence crop yield and quality depend, embraces its content of plant food (nutrients), its organic matter content, its structure, its ability to supply water and its depth. Excessive use of fertilizers with nitrogen products of ion nitric accumulation in the soil (temporary) and in plants, which disturbs the balance of photosynthesis, causes the appearance of necrosis and burns on leaves, severe intoxication and even death by asphyxiation phenomena and cyanosis at ruminants, children and old people. One of the ways of soil pollution through agricultural technology is overfertilization and, in particular, the administration of high doses of nitrogen fertilizers. Excess of nitrogen fertilizers, as well as their empirical application, have negative effects on harvest quality. The main aim of this study was to determine the effect of five nitrogen levels and different type of fertilizers on the agrochemical evolution of the chernozemic soil in the superficial horizon. Field experiments were conducted at the Agricultural Research and Development Station (ARDS) Suceava, Romania, in two growing seasons (2017 and 2018) with five nitrogen levels (80 kg/ha, 120 kg/ha, 160 kg/ha, 200 kg/ha and 240 kg/ha) and two type of nitrogen fertilizers (ammonium nitrate and urea).