The paper presents research results obtained in stationary experiments, carried out at Development Agricultural Research Station Oradea, regarding the influence of nitrogen and phosphorus fertilizers, on yield and soil fertility evolution. The research results obtained in long term experiments bring scientific arguments regarding necessity of rational application of nitrogen as a function of soil phosphatic potential in preluvosoil conditions. The kernel yield maize and it’s chemical composition are strong influenced by the N rates level and by the level of phosphatic potential. The higher yield level (65 – 68 q/ha) can be obtained only in the case of high potential phosphatic level (between 112 – 164 ppm). These levels can be obtained through annual P rates applied bigger than 80 kg P 2 O 5 /ha and N rates higher than 150 kg/ha. The N total (%) and protein content of maize kernel are proportional increasing, with increasing of N rates until 150 kg N /ha. The rates of 200 kg N /ha determine a decreasing of N total (%)and protein  content in special in the case of low level of phosphatic potential. Because of secondary soil acidification like a consequence of systematically N application, appear nutritive unbalance which limit the yield level obtained. In these soil conditions for increasing of fertility potential is necessary cyclic lime application and for technical plants (inside of crop rotation is necessary potassium and microelements).

phosphatic potential; nitrogen rate; nutritive unbalance; protein content

Presentation: oral