THE INFLUENCE OF SOIL TILLAGE AND NITROGEN FERTILIZATION ON MINERAL NUTRITION OF MAIZE

The paper presents aspects regarding some changes of physical and chemical soil properties in a long term ex-periment with different tillage methods. Also, some aspects regarding nitrogen and phosphorus metabolism in maize were investreated. The results shown that bulk density, soil porosity, soil aired porosity, distribution and nitrate and phosphorus content of soil were modified in disked and no-tillage variants compared with ploughed variants. These soil modifications influenced negatively nitrogen and phosphorus uptake and distribution in maize plants and finally reduced the yields. The nitrogen applied as fertilizer in soil stimulated the nitrate reductase activity which was very significant correlated in first vegetation phases with the level of total nitrogen accumulation in leaves (r= 0.91***, r = 0.73**) and with yield (r = 0.77**, r = 0.81**). Key words: bulk density, maize, N and P content, soil porosity