There is a broad agreement among researchers that the acids accumulating in soils and controlling the solution of carbonates - including the predominant CO2 - can be mostly derived from three groups of processes:

1. root respiration of higher plants;
2. decomposition of soil organic matter by microorganisms (microbiota);
3. other decomposition processes not associated with microbial activities.

We performed studies of corrosion on small samples.

The objective of the investigation was to allow the comparison of solution effects by absorbing the entire carbonate solution capacity originating in the soil. Limestone solution capacity is expressed by the concentration of dissolved carbonate (milligrams) or by the equivalent amount of CO2.

Model investigations covered the 4 most common karst soils (originating from the Aggtelek Karst region, Northeast Hungary) in the temperate and subtropical climatic belts:

1. black rendzina
2. brown rendzina
3. humous red-brown eath
4. relict red clay soil.

For each soil type 4 models involved the original microbiota and these models served to measure natural solution capacity. On the other hand, in four models for each soil type the soil was sterilised and here solution capacity without microbial action could be determined.

The solution capacity derived from microbial action was almost an order magnitude higher under rendzinas (in original samples) than the solution capacity not due to microbial sources (sterile samples). Under clay soils this effect is only half as intensive.

Solution capacity expressed by total dissolved carbonate content shows distinct values, characteristic for the individual soil types.

In each soil types studied, the solution caused by microbial activities manifold exceeds the rate of solution resulting from temperature factor but there is a manifest dropping trend from rendzinas to clays.

The elaborated method seems to be suitable to carry out the investigation under different climates. Through the alteration of conditions, further aspects of the soil effect can be revealed.