DYNAMICS OF NUTRIENT ACCUMULATION IN ABOV EGROUND PARTS OF SORGHUM

In a long-term field fertilization experiment on calcareous sandy soil , studies were made on the dynamics of nutrient accumulation in the ab oveground parts of the grain sorghum variety Alfoldi F 1. Specific nut rient contents were calculated. Plant samples were taken from an area of 0.36 m(2) in the major phenophases on a total of six occasions duri ng the vegetation period. The following conclusions can be drawn from the results. Among the macroelements, the accumulation of N, P, K, Ca, Na, S and Mg was continuous, though at differing rates, throughout th e vegetation period. Of the micronutrients, the accumulation of Mn, Zn and B proved to be continuous up to harvesting, while Fe and Cu were accumulated up to flowering, after which element loss, or reflux, was observed. The intensive phase of accumulation, when the sorghum plant accumulated the larger part of the total quantities absorbed, occurred after flowering for N, P, K, Mg, S and Mn and during the flowering ph enophase for Ca Fe, Zn, Cu, B and Na. The effect of N, P and K fertili zers in increasing the accumulation of all the elements was significan t over the average of the green plant samples in the NP and NPK treatm ents. At harvesting, fertilization caused significant differences in t he quantities of N and P in the grain yield, and of K, Fe, Mn and Cu i n the straw yield compared to the unfertilised control. At full maturi ty the majority of the N, P, S and Zn was found in the grain, and that of K, Ca Mg, Fe, Mn, B and Na in the vegetative parts, while Cu was f ound in roughly equal proportions in both parts. The specific nutrient content of 1 t grain yield + the relevant by-products averaged 26 kg N, 2.9 kg P, 10.8 kg K, 10 kg Ca, 5.2 kg Mg, 1.4 kg S, 142 g Fe, 73 g Mn, 28 g Zn, 6.8 g Cu and 4.8 g B in the grain sorghum variety Alfoldi F 1.