The interactions between K, B and Sr were examined in the Experiment Site of the Institute on calcareous chernozem adobe soil in alfalfa between 2001-2004. Before sowing, 400 kg ha-1 P2O5 was applied in the form of superphosphate as basic fertiliser. K levels were adjusted with repeated applications of 0, 1000 and 2000 kg ha-1 K2O, B levels with repeated 0, 20, 40, 60 kg ha-1 B and Sr levels with a single dose of 67 kg ha-1 Sr. The applied fertilisers were 60% KCl, 11% borax and 33% SrCl26H2O salt. 3 K treatments and 4 B treatments were applied per main plot and 2 Sr treatments were applied per sub plot, resulting in 72 plots (24 treatments x 3 replications) in a split-plot design.

Th experiment focusing on the interactions between K and B was established in the autumn of 1987 on the Nagyhörcsök Experiment Site of HAS RISSAC. The soil at the experiment site was calcareous chernozem adobe soil formed on loess and it contained around 5% CaCO3, 3% humus and 20% clay in the ploughed layer. According to the soil analyses performed in the autumn of 1987, the pH (H2O) of the topsoil was 7.8; while the pH(KCl) was 7.3. As regards mineral elements, the following values were obtained: AL-K2O: 180–200 mg kg-1, AL-P2O5: 100–120 mg kg-1, KCl-soluble Mg: 110–150 mg kg-1, KCl+EDTA soluble Mn: 60–80 mg kg-1, Cu and Zn 1–2 mg kg-1, hot water soluble B: 0.7 mg kg-1. Based on the methods and limit values accepted by the MÉM NAK system (1979), these data show the satisfactory Mn, B, Mg and K supply levels of the soil, medium N and P levels and weak Zn and Cu supply levels. The groundwater level is 13-15 m and the area is drought-sensitive. The mean temperature is 11 oC and the yearly precipitation sum is 400-600 mm with uneven distribution. Main conclusions to be drawn:

- The fertiliser impacts were not shown in yield in this calcareous adobe soil weakly supplied with both potassium and boron. Averaged over the whole experiment, the obtained yields were 4.4 t ha-1 (grain) and 4.6 t ha-1 (straw), resulting in 9.0 t ha-1 airdry biomass.

- The boron load doubled the amount of B incorporated into the grain, while its amount in straw increased four times. The boron fertiliser remained in the upper soil layers interlaced with roots even after seven years. B fertilisation decreased Mg concentration both in the grain and the straw. However, K fertilisation significantly increased K and Ba levels in the vegetable parts.

- The above-ground yield of winter barley withdrew 156 kg N, 86 kg K, 29 kg P, 21 kg Ca, 11 kg Mg, 4 kg Na, 1 kg Fe, 200 g Mn and Ba, >100 g Sr and Zn, 55 g B and 32 g Cu per hectare.

- The specific element content of 1 t grain and its secondary yield was 35-15-22-7-4=N-P2O5-K2O-CaO-MgO kg t-1 under experimental circumstances. Our obtained data could serve as a basis for calculating the element need of the planned yield in consultancy.

Keywords: potassium, boron, strontium effect, winter barley, element uptake