Farkas Csilla

Three soil tillage systems, representing three levels of soil disturbance, were tested for their effect on CO2 emission from the soil. For these studies, large (10 cm high, 10 cm in diameter) undisturbed soil columns were incubated in a climate chamber, thus combining the advantages of laboratory and field methods, as it was possible to record the CO2 emission from soils with undisturbed structure under controlled temperature and moisture conditions. A further aim was to optimise a newly elaborated measuring technique, with special regard to the determination of optimum incubation time. The data were evaluated and the timing of sample taking was optimised accordingly. No statistical difference was found between the emission values measured after 3 and 6 hours of incubation, so the time was set to 3 hours. A comparison of the emission values recorded for samples originating from the three soil tillage methods [ploughing (SZ), direct drilling (DV), disking combined with deep loosening (L+T)] indicated that the highest CO2 emissions arose from the direct drilling treatment and the lowest from the ploughing treatment. This could be attributed to the higher available organic C content in the less disturbed treatment. In the soil moisture content range tested, CO2 emissions were found to rise with an increase in soil moisture content at the beginning of the experiment, but in the fourth week a decrease was observed in the value of CO2 emission at soil moisture contents around the field water capacity. In all the treatments the emissions gradually declined as the substrates were exhausted. The results confirm that, due to the rapidity and complexity of processes taking place in the soil, it is necessary and important for mutually complementary field and laboratory measurements to be evaluated together.

Soil biological properties and CO2 emission were compared in undisturbed grass and regularly disked rows of a peach plantation. Higher nutrient content and biological activity were found in the undisturbed, grass-covered rows. Significantly higher CO2 fluxes were measured in this treatment at almost all the measurement times, in all the soil water content ranges, except the one in which the volumetric soil water content was higher than 45%. The obtained results indicated that in addition to the favourable effect of soil tillage on soil aeration, regular soil disturbance reduces soil microbial activity and soil CO2 emission.