Joint International Conference on Long-term Experiments ...

ABSTRACT
SOME LESSONS LEARNED FROM THE NYÍRLUGOS
LONG-TERM FIELD EXPERIMENT
Imre Kádár
Research Institute for Soil Science and Agricultural Chemistry
H-1022, Budapest, Herman Ottó Str. 15, Hungary. E-mail: kadar@rissac.hu
The paper reports results achieved in a 44-year-old field trial set up on acid sandy
brown forest soil in the Nyírség region. Characteristics of the site: pH (KCl) 4.3-4.6,
humus 0.5-0.7%, CEC 3-4 meq/100 g in the ploughed layer. The topsoil was poor in all
five macronutrients (N, P, K, Ca, Mg) and the groundwater depth was 2-3 m. Fertilizers
applied in form of Ca-ammonium nitrate, superphosphate, potassium chloride,
powdered limestone and dolomite. The following conclusions could be drawn:
1. As the result of the regular N fertilization the pH (KCl) value in the topsoil dropped
to 3.5 (control plots 4.3), while it rose to 6.4 after addition of 1 t/ha/yr CaCO3. As a
function of liming, the exchangeable Ca 2+ enhanced from 0.13 to 2.18 meq/100 g,
while Al 3+ decreased from 0.68 to 0.40, Fe 2+ from 0.43 to 0.15 meq/100 g; CEC
increased from 3.3 to 3.6-3.8, S-value (sum of bases) from 0.4 to 2.5 meq/100 g, base
saturation (V) from 12% to 69%.
2. The NH4-acetate+EDTA soluble (Lakanen and Erviö 1971) element contents in
plowlayer also mirrored the changes caused by liming and fertilization. So, Ca lifted
from 87 to 767, Mg from 18 to 97, Mn from 8 to 36, Sr from 0.4 to 2.7, Co from 0.15
to 0.53, Ni from 0.10 to 0.19 mg/kg.
3. Fertilizer responses were time dependent. In the 1 st decade of the experiment N alone
increased the potato and rye yields. In the 2 nd decade, the yield on N-plots declined
near to control. In the studied last few years, the yields on N-plots were negligible,
the soil lost its fertility and became leached and very acid. To maintain or increase
the yields of crops NPKCaMg fertilization was needed. Fertile plots have a pH (KCl)
5.5-6.0, 120-150 mg/kg ammoniumlactate-soluble P2O5 and K2O in plowlayer and
require the application of about 150 kg N and 1 t/ha ground dolomite yearly.
Keywords: fertilization, liming, time dependence, responses, long-term field
experiment
INTRODUCTION
There is a nearly universal acceptance of the fact that most long-term ecological
research is inherently interdisciplinary in nature. The successful performance of longterm
field experiments requires the special recognition of certain key elements in the
work. The scientific questions and objectives must be clearly defined and stated because
they must guide research for several generations of scientists, administrators and
funding agencies.
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