EFFECT OF VARIED LEVELS OF FERTILIZATION WITH POTASSIUM ON FIELD PEA YIELD AND CONTENT AND UPTAKE OF NITROGEN

Background. The aim of this study was to estimate the effect of different potassium fertilization rates on the yield and nitrogen content and uptake by field pea. Also, an attempt was made to make a modelled estimation of the amount of nitrogen biologically reduced by the bacteria Rhizobium leguminosarum living in symbiosis with field pea and free bacteria in the soil, in conditions of different rates of potassium fertilization.Material and methods. The study was carried out based on a field experiment in 2010 and 2012, in a completely randomized design with four replications, on experimental plots of the Siedlce University of Natural Sciences and Humanities. The study involved the application of nitrogen fertilization at a rate of 20 kg·ha-1 and six potassium fertilization levels: NK0; NK1; NK2; NK3; NK4; NK5. Potassium was applied at rates: K0 – 0; K1 – 41.5; K2 – 83; K3 – 124; K4 – 166; K5 – 207.5 kg·ha-1.Results. The significantly highest yields of field pea seeds were obtained in the treatments where the applied potassium fertilization rate was 124 kg·ha-1. Straw and pod yields were different in each year of the study. The content of nitrogen in seeds, straw and pods was significantly reduced under the influence of higher doses of potassium fertilizers. The highest nitrogen uptake in the yield of field pea was found in the variant where the rate of potassium was 124 kg·ha-1.Conclusion. The study showed that to obtain the highest seed yield, the highest 1000 seed weight and the highest nitrogen uptake with the total yield of field pea, the optimal potassium rate was 124 kg·ha-1.