Like nitrogen and phosphorus, potassium is major nutrition`s element contributing to large, steady an high quality crops. Potassium is a multifunctional and high mobility element with direct and indirect influence on almost all biochemical and physiological processes. Potassium is associated with movement of water, nutrients, and carbohydrates in plant tissue. If K is deficient or not supplied in adequate amounts, growth is stunted and yields are reduced. Various research efforts have shown that potassium stimulates early growth, increases protein production, improves the efficiency of water use and improves resistance to diseases and insects. The corn crop was grown on cambic chernozem, poorly glazed, the largest soil type on the USAMVB`s Research Station from Timisoara. The stationary experiment performed in the field was based on the rotation of the cultures wheat - corn – sun flower. Each plot was subdivised in four repetitions in liniar disposition, one after the other. The experiment was done on corn hybrid: Lovrin 400. Treatments applied were: 0, 50, 100, 150 and 200 kg•ha-1 nitrogen and 0, 50, 100 and 150 kg•ha-1 phosphorus and potassium. Soil potassium content was determined trough Egner – Rhiem – Domingo method (AL – K). Protein content of corn grains was determined with Kjeldahl method and starch content with Ewers – Grossfeld method. The experimental dates were estimated by multivariate analysis of variance (ANOVA). A rise in the level of mobile potassium in soil proportional to the increased dose of mineral fertilizers with phosphorus and potassium was recorded all through the research years. The levels of exchangeable potassium goes down while that of the nitrogen fertilizer dose goes up, the highest soil potassium content values occur when the nitrogen fertilizer does not apply. Unlike nitrogen fertilizers, fertilizers with phosphorus and potassium influence the amount of raw protein in the grain of corn to a smaller extend and when applied in larger quantities they entail their decrease. High doses of potassium and phosphorus on plots pre – fertilized with small and fairly large amounts of nitrogen (0 and 50 kg•ha-1) lead to an increased level of starch in the grains of corn. For good soil potassium supply, high and quality corn yields we recommend annual application rates of 100 to 150 kg•ha–1 K alongside nitrogen and phosphorus.

fertilization, potassium, maize, raw protein, starch

Presentation: oral