Impact of selected agrochemical treatments on the content of molybdenum in grain of winter wheat and spring barley grown on lessive soil developed from loess

This paper presents results of a study on the molybdenum content in grain of winter wheat and spring barley grown on a permanently fertilized field on loessial soil in the Rzeszow Foothills (Podgórze Rzeszowskie), in Poland. The experiment was set up in randomized sub-blocks, with potato, spring barley, fodder sunflower, and winter wheat plants grown in 4 four-year rotation cycles. Fodder cabbage was grown instead of sunflower in the second crop rotation. The first variable factor was liming (A2) or its lack (A1), while the second one consisted of different doses of mineral fertilization. Mineral NPK nutrition was applied together with constant Mg as well as Mg and Ca fertilization (liming). The general fertilization level (N1 P1 K1) for spring barley was 80 kg N ha-1, 43.6 kg P ha-1 and 99.6 kg K ha-1, while for winter wheat it was 90 kg N ha-1, 34.9 kg P ha-1 and 83 kg K ha-1. Constant magnesium fertilization was applied at a 24.1 kg Mg ha-1 dose. Liming at a dose of 4 t CaO ha-1 was applied before starting the experiment and in each year that completed a subsequent crop rotation cycle. There was a significant increase in the molybdenum concentration in grain of winter wheat and spring barley due to the liming applied. A moderate molybdenum content was found in winter wheat grain on non-limed soil 0.278 mg kg-1 DM and on limed soil 0.320 mg kg-1 DM; while in spring barley grain on non-limed soil, it equalled 0.291 mg kg-1 DM and on limed soil 0.455 mg kg-1 DM. Mineral fertilization increased the content of this component in wheat grain and usually or most often reduced its amount in barley grain. The interaction of liming with mineral fertilization did not have any significant effect on the molybdenum content of winter wheat grain and resulted in an increase in the molybdenum content in spring barley grain.