Joint International Conference on Long-term Experiments ...

THE EFFECT OF BENTONITE ON SPECIFIC SOIL PARAMETERS AND
MICROBIAL CHARACTERISTICS OF THE CARBON CYCLE
János Kátai 1 , Magdolna Tállai 1 , János Lazányi 2 ,
Edina Veres Lukácsné 1 , Zsolt Sándor 1
1 University of Debrecen, Centre of Agricultural Sciences,
Department of Agrochemistry and Soil Science
2 University of Debrecen, Centre of Agricultural Sciences,
Department of Rural Development and Land Use
ABSTRACT
The effect of increasing dosages (5, 10, 15, 20 t/ha) of bentonite (Bentonite experiment)
and bentonite composted with manure (Bentonite + manure experiment) was studied in
a small plot experiment on acidic sandy soil at the Experimental Farm of the
Nyíregyháza Research Centre, UD CAS. The effect of treatments on the physical,
chemical and microbial soil parameters can be summarized as follows:
• Bentonite significantly increased the water-holding capacity of soils. In samples
treated with bentonite moisture content was 2-3 % higher than that in treatments
with bentonite and manure.
• The pH value of the soil was shifted towards neutral. In bentonite treatments, pH
was more increased than in treatments of bentonite composted with manure.
Accordingly, hydrolytic acidity was also reduced.
• When studying the nutrient content of soil, we found that bentonite increased,
though not always significantly, the readily available potassium content of soil. As
a result of the composted treatments, the readily available nitrate, phosphorus and
potassium content of the soil significantly increased.
• Regarding the studied microbial parameters, we found that the composted
treatments caused a higher (though not always significantly) increment in the total
number of bacteria, the number of microscopic fungi and cellulose-decomposing
bacteria and the biomass-C content of soils. In both series of treatments, the high
dosages caused a reduction in the number of microbes.
High bentonite dosages also reduced carbon dioxide formation.
Saccharase activity was significantly increased by small dosages of bentonite, while
composted treatments resulted in a lower, not significant increment in enzyme
activities.
• In the experiment, several relationships were found between the physical, chemical
and microbial soil parameters.
Keywords: bentonite, moisture content, pH, quantitative changes in microbes,
microbial activity
INTRODUCTION
Nowadays, sustainable agriculture is a worldwide known notion, a basis of which is the
protection of the environmental elements and reducing the environmental loading to the
minimum. These aspects should also be considered in soil melioration, therefore,
increasing attention is paid to the study and application of natural, environmentally
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