Joint International Conference on Long-term Experiments ...

Nosticzius, 1992). Among these, soil parameters, nitrogen and water supply are the
most decisive ones. The nitrogen and the water supply significantly modified the
dynamics of nutrient uptake at the different crops (Borchmann, 1963). It should be
noted, however, that there are significant differences in the plant species’ ability to take
up the nutrients (Eichler et al., 1997; Eichler and Köppen, 2001; Eichler, 2004).
The identical nitrogen and water supply has a different effect on the soil types. To
investigate this phenomenon, a vegetative pot experiment was set up on three extremely
different soil types from the near of Debrecen. The advantage of the pot experiment is
that several factors (e.g. water supply) can be controlled and the same conditions can be
ensured for all the treatment combinations. In addition, the amounts of added nutrients
are exactly known due to the size of the pot and the roots of the plant interwove the
whole pot.
Perennial ryegrass (Lolium perenne L.) was used as a test plant. The advantage of
this plant is that it endures well the conditions of the greenhouse and it can be cut
several times during the vegetation period, therefore, the dynamics of the processes can
be concluded too.
In the greenhouse experiment, the effect of different nitrogen and water supply on
the plant’s dry matter production and its dynamics was examined. The nitrogen
concentration of the yielded shoot dry matter was measured and the amount of nitrogen
extracted from the soil by the plant was calculated for the different cuts and for the
whole period of the experiment.
MATERIALS AND METHODS
In the Table 1 are included the basic initial parameters of the three untreated soils used
in the pot experiment. The initial total carbon and nitrogen content of soils was
measured by Nagy, P. T. (2000). Calculated for air-dry state, 2.5 kg of brown forest
soil, and of chernozem soil and 2.0 kg of marshy meadow soil were put separately into
plastic pots of 2.0 dm 3 volume.
The standard background treatment of each experimental pots was a joint 10 cm 3
solution of 40 mg kg -1 P2O5 and 40 mg kg -1 K2O, as pro anal. compounds of KH2PO4
and K2SO4 in distilled water.
The treatment combinations applied on the three soils are shown in Table 2. Each of
them was carried out in four replications to ensure the possibility of statistical
evaluations.
The transpirated and evaporated water was supplemented by irrigating the soils
with distilled water. In the treatment plan given water supply level set up was ensured
by daily irrigation of the vegetation pots to a calculated specific weight. At high
vegetative mass, and also on the hot days plants were irrigated in the afternoon to avoid
the threat of wilting.
Plants were cut three times, first time five weeks after the sowing, the 2 nd and the 3 rd
times in three weeks intervals. The grass shoot yield was first air-dried and after that
dried at 60 ºC until reaching constant mass in a desiccator. The dry matter production
per pot was measured by analytical balance.
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