Joint International Conference on Long-term Experiments ...

EVALUATION OF THE DATA SET OF THE HUNGARIAN LONG-TERM
K-FERTILIZATION FIELD TRIALS, SET UP BETWEEN 1960 AND 2000
Péter Csathó
Research Institute for Soil Science and Agricultural Chemistry of the Hungarian
Academy of Sciences, H-1022 Budapest, Herman O. út 15, Hungary.
ABSTRACT
Potassium is considered to be the third most important macronutrient in Hungary
following nitrogen and phosphorus. The magnitude of responses to K application is
effected not only by the available K levels in the soil, but by the crops, too.
Evaluating the results of Hungarian 1- to 10-years-old long-term potassium fertilization
field experiments found in the literature between 1960 and 2000, conclusions were
made as follows:
The connection between the AL-K content of K-control (NP) plots and the
responses to K, expressed in relative yields (100Yield in NP plot/Yield in NPK plot,%)
could be described by a Mitscherlich-like equation, modified by Bray (1944): / Y'= 100
(1-10 -cx ) /, where x = AL-K content in the K-control (NP) plots; Y' = relative yield in
the trials, having "x" AL-K contents in the K-control plots; and c = proportional
constant (Mitscherlich's "working factor").
As a result of K application, surplusses in maize were higher than in winter wheat
or alfalfa. Average surplusses in maize grain yields varied between 0.0 and 1.9 t/ha, in
alfalfa between 0.0 and 1.6 t/ha and in winter wheat between 0.1 and 0.4 t/ha, resp.
The AL- (ammonium-lactate) (Egner, Riehm and Domingo 1960) soluble K indicated
the natural K- supplying power of the different soils adequately.
Keywords: field trials, potassium, soil texture, Bray-Mitscherlich approach, new
fertiliser recommendation system
INTRODUCTION
In the early 60's, when intensive (NP) K fertilization had not been introduced, about
half of the arable land in Hungary was poorly or moderately supplied with K. For that
reason the synthesis of the national field trial series of the above two crops is especially
important (Corey 1987). Alfalfa is also among the most important crops produced in the
country. As a first attempt, the data set of K fertilization trials with winter wheat, maize
and alfalfa has been established.
MATERIALS AND METHODS
A database of the results of 1- to 10-year-old Hungarian potassium field experiments
with maize, winter wheat and alfalfa, found in literature was compiled. A large number
of these trials belong to the National Long-term Field Trial Series with Fertilizers
(OMTK), supervised by the Pannon Agricultural University, Keszthely. In all trials,
by-products were removed from the fields. Soil characteristic data of NP (K-control)
treatments, grain yield data of NP and also NP+K treatments giving maximum
economic yields (about 95% of the maximum yields) were collected. The results were
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