Joint International Conference on Long-term Experiments ...

THE CA AND MG SUPPLY OF THE SOIL EXTRACTED WITH DIFFERENT
SOLVENT SOLUTIONS
István Kocsis 1 Lajos Szabó 1 Simándi Péter 1 László Pásztor 2
1 Tessedik Sámuel College, Faculty of Agricultural Water- and Environment Management
H-5540 Szarvas, Szabadság str. 1-3., Hungary
2 Plant and Soil Protection Service of the Jász-Nagykun-Szolnok County, Szolnok
INTRODUCTION
Information upon Ca content of the soil used to be crucial
• if in the arable layer, calcium carbonate is lacking, and
• if calcium content of the soil is excessive in relation to the colloidal capacity of the
respective layer (Filep, 1988, Németh, 1971, Filep, 2002.).
There are alternative methods for characterising the Ca content of soils. The soils are well
supplied with calcium:
• if the content of CaCO3 is between 1 and 5 % measured with the method of Scheibler
• if the measured AL-Ca values are about 50-100 mg/100 mg in sandy soils, 100-200
mg/100 g in loam soils, and 500-700 mg/100 g in clayey soils.
• if the Ca content is exchangeable at a 70-80 % rate of the S value
• if the Ca values obtained with the EUF method are within the interval 35.0-60.0 mg/100
(Filep 2002)
Results of the method according to Scheibler are not informative for soils containing little
Ca, whereas extraction with AL gives erroneous results for calcareous soils. Determination
of exchangeable cations is performed with different solvents than with other nutritive
elements. The EUF method measures Ca together with other elements, however, it requires
a special device.
Excessive or insufficient Ca disturbs the uptake of other elements in the soil. The rule
of calcium-potassium influencing the absorption of phosphorus by Ca as well as the
antagonisms of Ca:Mg and Ca:K are widely recognised. The role of Ca and Mg influencing
the uptake of meso- and micro-elements is also known (e.g. abundance of Ca may cause
chlorosis due to iron deficiency). The Ca-EUF Mn ratio indicates that two agricultural
elements, the liming and the loosening of the soil could be applied.
The ratio between the contents of lime and colloids is considered as an important parameter
of the soil. The Ca status should reasonably reflect the availability of both macro- and
microelements. Information related to the Mg status is necessary mainly in sandy and in
alkaline soils. Relevant methods are largely similar to those applied in the case of Ca
determination. The solvent solution however should not contain the element in question:
(e.g. Ca salt is suitable for assessing Mg e.g. 0.01 M CaCl2). For Ca and Mg extraction KCl
solution is recommended. In assessing the Ca content available for the plants, mild solvents
give more reliable information than the more concentrated ones. For the determination of Ca
content, we used mild solutions, which facilitated the measurement of other elements too.
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