The effect of different levels of NPK supply and their combinations on the yield, development and N uptake of the eight-component grass mixture without papilionaceae in which meadow fescue (Festuca pratensis) was the dominant species was examined in 2007, the 34th year of a long-term fertilisation experiment. The ploughed layer of the production area contained 3% humus, 3–5% CaCO3 and 20–22% clay. The soil was moderately supplied with N and K and weakly supplied with P and Zn. The experiment consisted of 4N × 4P × 4K = 64 treatments × 2 replications = 128 plots. The soil water level is 13–15 m, the area is drought sensitive. The previous crop of grass was spinach and the grassland was established on 20th September 2000, using the row spacing of cereals at 60 kg sowing seed per hectare. The main results are as follows:

There was only one reaping in the dry year of 2007. There was 0.5 t ha-1 hay yield on the soil which has not been fertilised for 37 years, while 4.0 t ha-1 was obtained on the field which was fertilised with 300 kg ha-1 year-1 N and a satisfactory amount of P. Phosphorus fertilisation was ineffective, but the efficacy of N fertilisation was also moderate on P deficient plots. The increase of K supply did not result in significant yield increase on this plot which was moderately supplied with K.

The quantities of most examined elements (metals, cations) increased with K supply in hay. The dilution resulting from higher yield slightly decreased the K, P and S content. Nitrate-molybdenate antagonism was observed, while the incorporation of Mo was blocked as a result of N abundance. The quantity of P and S increased and the amount of Zn and Mo decreased in hay as the P supply increased due to the known P-Zn and phosphate – molybdenate antagonism. The K fertilisation increased the K content and significantly reduced the incorporation of Ca, Mg, Na, Sr, Cu cations and B.

As a result of the interactions between N and P, the amounts of the examined elements ranged between the following extreme values: P 0,14–0,40%, S 0,13–0,23%, NO3-N 0,2–3,2 g kg-1, Zn 12–23 mg kg-1, Sr 10–24 mg kg-1, Mo 0,5–2,3 mg kg-1. On the supply levels/combinations of N and K, the following ranges were observed K 1,1–2,2%, Ca 0,4–0,8%, Na 0,1–1,5 g kg-1 and B 4–6 mg kg-1.

The observed nutrient proportions also characterised the nourishment status of hay. In the case of high yields, the amount of N was above 2%, while that of P was above 0.2%; therefore, the proportion of N/P was around 8–10. In accordance with the references, the P/Zn ratio was 100–150 on fertile soil, the ratio of P/NO3-N was around 200, while the proportion of Cu/Mo was found to be around 10. The extreme N shortage was shown by the fact that the ratio of N/P was around 3, the significant Zn shortage was shown by the P/Zn ratio which was above 300, while Cu shortage was getting more and more severe, which was shown by the fact that the Cu/Mo ratio decreased to around 2. The induced element disproportions could be observed by crop analysis, and the nourishment status can be diagnosed.

As a result of the N and P supply, the following amounts of elements were taken up per hectare: 5–96 kg N, 2–26 kg Ca, 2–11 kg P, 1–7 kg Mg, 0,1–8,0 kg NO3-N. As regards microelements, the following values were measured: 34–405 g Fe, 25–354 g Mn, 18–210 g Al, 5–95 g Sr, 7–89 g Zn, 2–20 g B, 1–15 g Ba és Cu, 0,7–4,0 g Mo, 0,1–1,4 g Ni, 0,01–0,11 g Cd per hectare. The g ha-1 levels of As, Hg, Cr, Se, Co were below the detection level. Levels of K (8–84 kg ha-1), Na (0,1–4,9 kg ha-1) and Mo (0,6–3,6 g ha-1) showed extreme values concerning N and K levels.

The specific element need of the examined grass hay without papilionaceae for the production of 1 t hay under the given experimental conditions, excluding extreme values was shown to be the following: 10–23 kg N, 12–20 kg K (14–24 K2O), 4–6 kg Ca (5–8 kg CaO), 2–3 kg P (4–7 kg P2O5) and around 2 kg Mg (3–4 kg MgO). These data could be informative in the technical advice system during the calculation of the element need of the planned yield.

Keywords: established grassland, NPK fertilisation, hay yield, mineral elements