A kálium, bór és stroncium kezelés hatása a koronafürtre (Coronilla varia L.) | Effect of potassium, boron and strontium treatment on crown vetch (Coronilla varia L.)

Interactions between the elements K, B and Sr were investigated on a chernozem loam soil with lime deposits at the Nagyhörcsöki Experimental Station of the institute in the Mezőföld region of Hungary between 1988 and 2004. The K and B levels were adjusted using repeated doses of 0, 1000 and 2000 kg·ha –¹ K2O and 0, 20, 40 and 60 kg·ha –¹ B, and the Sr levels using rates of 0 and 67 kg·ha –¹ Sr. The fertilisers were applied in the form of 60% KCl, 11% borax and 33% SrCl ₂ × 6H ₂O. The 3 K treatments formed the main plots, the 4 B treatments the subplots and the 2 Sr treatments the sub-subplots, giving a total of 24 treatments × 3 replications on 72 plots in a split-plot design. When the experiment was set up in autumn 1987 the ploughed layer contained 5% CaCO ₃, 3% humus and 20% clay, with pH(H ₂O) 7.8, pH(KCl) 7.3, and element con-tents (mg kg ⁻¹) of 180–200 AL-K ₂O, 100–120 AL-P ₂O ₅, 110–150 KCl-soluble Mg, 60–80 KCl+EDTA-soluble Mn, 1–2 Cu and Zn, and 0.7 B. The soil was satisfactorily supplied with K, Ca, B and Mg, moderately well with N and P, and poorly with Zn and Cu. The groundwater was located at a depth of 13–15 m and the area was prone to drought. The mean temperature averaged 11 °C, and the annual rainfall sum was 400–600 mm, with uneven distribution. The main conclusions drawn from the results were as follows: By the 13 ᵗʰ year of the experiment the AL-soluble K ₂O content in the ploughed layer, which was originally satisfactorily supplied with potassium and boron, had dropped from 180–200 mg·kg ⁻¹ to 140 mg·kg ⁻¹. K effects gradually became more pronounced; the seven cuts of crown vetch over the 4 years removed 572 kg K ₂O·ha ⁻¹ from the soil. Compared with the K control the 2 ⁿᵈ cut in 2004 gave a surplus of 10 t·ha ⁻¹ fresh and 1 t·ha ⁻¹ air-dry hay and the dry matter content of the fresh yield was 2% lower on average. The B and Sr treatments had no significant influence on the yield quantity. The total hay yields over the four years (seven cuts) amounted to 110–120 t·ha ⁻¹ (fresh) and 21–24 t·ha ⁻¹ (air-dry). K fertilisation inhibited the incorporation of Ca, Mg, Na and Sr cations into the hay, with a simultaneous increase in the K content. Even after 10–14 years B fertilisation resulted in a multiple increase in the B content of the hay. The B accumulation in the small yield of aging hay was as high as 372 mg·kg ⁻¹. In most cases the 67 kg·ha ⁻¹ Sr dose applied 9–12 years earlier significantly reduced the uptake of the antagonist element Na. The optimum supply levels of 2–5% N, 2–4% K, 1–3% Ca, 0.3–0.8% Mg, 0.3–0.7% P and S, and the mg kg ⁻¹ levels of 30–200 Fe and Al, 30–100 Mn, 35–80 B, 20–0 Zn, 5–15 Cu and 0.5–2.0 Mo, published for alfalfa in the green-bud stage and checked in the present work, could also be suitable for judging the nutrient status of crown vetch. The mean/specific element contents of 1 t hay yield were approximately 34 kg N, 22 kg K (26 kg K ₂O), 20 kg Ca (28 kg CaO), 3.5 kg P (8 kg P ₂O ₅), 3.1 kg Mg (5 kg MgO), 2.7 kg S, 216 g Fe, 149 g Al, 66 g Mn, 70 g Sr, 16 g Na, 28 g B, 15 g Zn, 6–7 g Cu and 4–5 g Ba on this soil. These data can be used by the extension service when calculating the element requirements of the planned yield. It must also be taken into consideration that crown vetch meets most of its N requirements by fixing atmospheric N, while the specific contents of Zn and Cu were moderate due to the poor Zn and Cu supplies at this location. With regard to the feed value of crown vetch hay, the crude protein content and crude fibre content were found to exceed those of standard alfalfa hay by 29% and 26%, respectively, while the crude ash and crude fat contents were 11% and 27% lower, respectively. Of the 17 amino acids analysed, the protein of crown vetch hay was found to be extremely poor in cystine (CYS), but extremely rich in prolamine (PRO) and aspartic acid (ASP). The other amino acids exhibited no significant differences (10–20%) between the two legumes. All in all it can be concluded that crown vetch could be competitive with alfalfa in terms of both hay yield and nutritional value, especially on poorer soils.