ACTA AGRONOMICA TOMUS 28. (A MTA AGRÁRTUDOMÁNYI KÖZLEMÉNYEI, 1979)

1979 / 1-2. szám - B. HELMECZI-L. KÁRPÁTI: Effects of varying rates of liming on the microbiological activity of the soil in a model experiment

Acta Agronomica Academiae Scientiarum Hungaricae, Tomas 28 (1—2), pp. 1—12 (1979) EFFECTS OF VARYING RATES OF LIMING ON THE MICROBIOLOGICAL ACTIVITY OF THE SOIL IN A MODEL EXPERIMENT By B. HELMECZI, L. KÁRPÁTI AGRICULTURAL UNIVERSITY, DEPARTMENT OF SOIL SCIENCE AND MICROBIOLOGY, DEBRECEN Soil microbiology studies were made on samples taken from model experiments performed under laboratory conditions. The model experiment was set up with two soil types (clay-washed brown forest soil and meadow soil) obtained from three growing sites, and 0.5, 1.0 and 2.0 doses of lime were used to neutralize the yt value. In the course of laboratory analyses the total number of bacteria in the soil, and the amounts of nitrifying, aerobic ammonifying, N,-binding and cellulose decomposing bacteria were determined according to Pochon. The results were evaluated in comparison with the numerical values obtained with pots not treated with lime (control). On the basis of the serial examinations performed so far the following observations were made. In elay-washed brown forest soil the activity of bacteria belonging to the physiological groups examined was stimulated to the greatest extent by the 0.5 dose of lime; the number of bacteria was the highest in this case. On meadow soil the full dose (1.0) of lime proved to be the most favourable; it primarily promoted the activity of the nitrify­ing and aerobic cellulose decomposing bacteria, and the number of these bacteria grew in the greatest measure. The effect of the double dose (2.0) of lime was less than that obtained with 0.5 or 1.0 doses of lime in almost every case. On the basis of the examina­tions carried out so far it seems probable that in treating acidic soils with lime, half the amount of lime required to neutralize the yt value is efficient from the point of view of stimulating the activity of soil bacteria in clay-washed brown forest soils, while the full dose of lime may be necessary for meadow soils. Introduction 51% of Hungarian soils have unfavourable properties which require improvement in the interests of efficient farming. Of this 51%, 34% is made up of acidic soils, the rest consisting of alkali and sandy soils. A large proportion of the acidic soils in Hungary is made up of acidic forest soils and meadow soils. The effect of liming on the properties of acidic soils and on the activity of the microorganisms living in the soil has been dealt with by many re­searchers. According to BERGLUND (1971), under the influence of liming the struc­ture of the clay in heavy soils becomes stabilized, and large, permanent grains are formed. TISDALE—NELSON (1966) found that besides promoting the growth of plants in some soils, liming increased the amount of phosphorus available to the plants and had a positive effect on the microorganisms in the soil. Nitrification is particularly promoted by liming, as most of the organisms transforming ammonium into nitrate require large quantities of active calcium. The non-symbiotic nitrogen-binding organisms also fix the N2 content of the atmosphere in larger quantities when the soil is adequately limed. Acta Agronomica Academiae Scientiarum Hungaricae 28,1979 1

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