Növénytermelés / Volume 62 / Issue 1 (March 2013) / pp. 19-35
The effect of potassium, boron and strontium treatment on grain sorghum
In 1995, the 8th year of the long-term experiment, the correlations between K, B and Sr were examined on calcareous chernozem loamy soil. The K levels were adjusted with repeated 0, 1000 and 2000 kg ha-1 K2O doses, B levels with repeated 0, 20, 40 and 60 kg ha-1 B doses and Sr levels with 67 kg ha-1 Sr dose. 60% potassium salt, 11% borax and 33% SrCl2×6H2O salt were used. 3 K treatments were used per main plot, 4 B treatments per subplot and 2 Sr treatments per sub-subplot, which calculates to 24 treatments×3 replications=72 plots in a split plot design. The basic fertilisation was 100–100 kg ha-1 year-1 N and P2O5 doses in the form of CAN and superphosphate.
In the autumn of 1987, at the time of establishing the experiment, the ploughed layer contained 5% CaCO3, 3% humus and 20% loam. Further soil characteristics were as follows: 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 mg kg-1. The production site had adequate K, Ca and Mg content; moderate N and P content and weak Zn and Cu content. 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:
– Grain sorghum had 19.6 t ha-1 green mass with 40% moisture content on 11th October 1995. During the wet autumn, no seed was grown in grain sorghum. The air-dry above-ground biomass weighed 14 t ha-1. Under similar circumstances, grain sorghum cannot be competitive with maize production, which resulted in 13 t ha-1 grain+7 t ha-1 stem yield the same year and on the same production site.
– There are no fertiliser effects on the calcareous loamy soil adequately supplied with potassium and boron. Even the extremely high, repeated 2000 kg ha-1 K2O and 60 kg ha-1 B doses did not cause any yield decrease. The Sr fertilisation did not have any effect on yield either.
– The K doses increased the K and Ba content of the sorghum shoot and its leaf at floweing, while the Ca, Mg, Na, Mn and Sr concentrations decreased. Based on the leaf analytical optimums, the level of Zn supply of the crop stand and the production site did not prove to be satisfactory.
– According to our calculations, the amount of elements incorporated into the 14 t ha-1 air-dry biomass is as follows: 18 kg N, 168 kg K (202 kg K2O), 20 kg P (46 kg P2O5), 36 kg Ca (50 kg (CaO), 19 kg Mg (32 kg MgO), 17 kg S. Of microelements, the following values were obtained: Fe 2.3 kg, Mn 1 kg, Na 0.6 kg, Al 0.5 kg. Furthermore, the following element contents were obtained: Zn 168, Sr 140, Cu 98, B 84, Ba 56, Ni 8, Pb 6, Se 3, Cr 2, Cd and Mo 1 g ha-1. Therefore, the harvested yield makes the soil weakly supplied mostly with N and K. Our data serve as indication during the calculation of the element need of grain sorghum during consultancy.
– The AL-K2O content of the soil increased from 191 mg kg-1 (measured on the control plot) to 515 mg kg-1, and the hotwater-soluble B content increased from 0.7 mg kg-1 to 5.1 mg kg-1 with the maximum doses.
Keywords: potassium, boron, strontium treatment, fertilisation experiment, grain sorghum