The interactions between K, B and Sr were examined on calcareous chernozem loamy soil at the Nagyhörcsök Experiment Site of HAS RISSAC in Mezőföld in the 10th year of the experiment with bean as indicator plant in 1990. K levels were adjusted with repeated 0, 1000, 2000 K2O treatments, B levels with repeated 0, 20, 40, 60 kg ha-1 B and Sr levels with a 67 kg ha-1 Sr dose. 60% KCl, 11% borax and 33% SrCl2 x 6H2O salt were used as fertiliser. The fertiliser treatment had the following setup: 3K per main plot, 4B per sub-plot, 2Sr per sub-sub-plot with 24 treatments × 3 replications = split plot design with 72 plots altogether. At the time of establishing the experiment in the autumn of 1987, the ploughed layer contained 5% CaCO3, 3% humus and 20% clay. Further soil characteristics: pH(H2O) 7.8; pH(KCl) 7.3; AL-K2O 180–200, AL-P2O5 100–120, KCl-soluble Mg 110–150, KCl+EDTA-soluble Mn 60–80, Cu and Zn 1–2, hot water-soluble B 0.7 mg kg-1. The production site has satisfactory K, Ca, B and Mg supply, average N and P supply and weak Zn and Cu supply. The groundwater level is 13-15 m and the area is drought-sensitive. The average mean temperature is 11 oC and the annual precipitation sum is between 400-600 mm with uneven distribution. Main conclusions to be drawn: - In this drought year, both K and B fertilisation reduced both the thousand grain weight and grain yield of bean, while the stem yield was not affected. Sr treatments had no effect on yield. The air-dry above-ground biomass was 3.9 t ha-1 of which the stem weighed 2.7 t ha-1. The grain yield was between 1.0-1.4 t ha-1 depending on the given treatment. - The B content of stem doubled as a result of B fertilisation, but it also increased in the grain by 30%. Also, Sr fertilisation significantly increased the Sr concentration in the stem and the grain. As a result of increasing K supply, the K concentration increased 2.6 times, while the Ca and Mg contents decreased. - The 1 t grain yield and its associated secondary yield had the following specific element contents: 78-56-31-13-10=N-P-K-Ca-Mg-P kg t-1. In our experiment, the rather wide spectrum of straw/grain ratio and the extremely high specific K, Ca and Mg element contents under drought conditions in the dry year could be misleading. We consider the guide numbers prevously communicated to consultancy (20-30-30-10=P2O5-K2O-CaO-MgO) to be acceptable in estimating the element need of the planned yield. - 81% of B, 83% of Mg, 95% of Ca and 97% of Sr incorporated into the above-ground biomass was accumulated by straw which is ploughed back into the soil. The majority of N taken up by the plant originates from the air which then will also enrich the soil by ploughing the stem back into it. Under similar circumstances, bean production could lead only to P shortage in the soil.

Keywords: potassium, boron, strontium, long-term experiment, bean