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• The effects of fertilization on 2 year old established swards. Mineral uptake 7.

  107-118

  Imre Kádár

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  The effects of different N, P and K supply levels and their combinations were examined on the mineral element uptake of an established 2 year old all-grass sward in the 29th year of a long-term fertilization field experiment set up on a calcareous chernozem soil. The soil of the growing site contained around 3% humus, 3-5% CaCO3, 20-22% clay in the ploughed layer and was originally moderately well supplied with available N, K, Mg, Mn and Cu and poorly supplied with P and Zn. The trial included 4N×4P×4K=64 treatments in 2 replications, giving a total of 128 plots. The fertilizers applied were Ca-ammonium nitrate, superphosphate and potassium chloride. The groundwater table was at a depth of 13-15 m and the area was prone to drought. In 2002 the area had 401 mm precipitation and gave 2 cuts of grass. The lay-out and method of the trial as well as the fertilizer responses on the hay yield and element content were published earlier (Kádár 2006). The main conclusions drawn as follows:
  1. While the hay yield was basically determined by N-fertilization which lifted the hay mass 5 times compared to the N-control, the uptake of elements was drastically modified through the N×K and N×P synergistic and antagonistic interactions.
  2. As a function of N×K treatments the uptake K changed for example at the 1st cut between 23-198 kg/ha, at the 2nd cut between 9-80 kg/ha. At the same time the uptake of Na fluctuated between 0.05-7.15 kg and 0.4-4.4 kg/ha, that of Mo 0.4-3.2 g/ha and 0.2-2.3 g/ha resp. As a function of N×P treatments the uptake of P changed at the 1st cut between 3-14 kg/ha, Sr between 12-388 g/ha, Mo between 0.5-4.5 g/ha. The nutrient accumulation at the 2nd cut showed an analogical picture.
  3. The K-fertilization stimulated accumulation of K and Ba, while inhibited the antagonistic metal cations’ uptake of Ca, Mg and Na. The increased P-supply rose the absorption of P, S, Sr and Ba while diminished the extracted amount of Mo, which dropped down by 1/3rd compared with the control. The liberal N-supply stimulated the incorporation of N, K, Mn, Sr and Cu resulting an increase of an order of magnitude.
  4. Between the two extreme supply levels (N0P0K0 and N3P3K3) there were found extreme differences in element uptake in 2002 as follows: 34-302 kg/ha K, 15-168 kg/ha N, 8-35 kg/ha Ca, 5-22 kg/ha S, 4-22 kg/ha P (9-51 kg/ha P2O5) and 3-14 kg/ha Mg. The incorporated Mn, Sr, Zn and Cu enhanced an order of magnitude on N3P3K3 plots compared to the N0P0K0 absolute control. Uptake of As, Cd, Co, Cr, Hg, Pb and Se left behind the detection limit of 1 g/ha.
  5. To have 1 t air-dry hay it was used by grasses 17-35 kg K, 9-19 kg N, 3-5 kg Ca, 2.0-2.5 kg S, 1.3-2.5 kg P (3.0-5.7 kg P2O5), 1.4-1.9 kg Mg, 170-980 g Na, 90-170 g Fe, 60-120 g Mn and Al, 10-50 g Sr, 7-25 g Zn, 3-6 g Ba, B and Cu, 0.3-1.3 g Mo and 0.4-0.9 g Ni. Data illustrate the nutrient turnover of a grassland and may be used for assessing the nutrient demand of all-grass sward.