Our measurements were done in a soil conditioner experiment started in 2014 which was set in conventional tillage system at the Karcag Research Institute where a soil conditioner was used from 2010. Effect of two different soil conditioners on compaction, moisture content of the soil and on CO₂-emission was studied. Measurements were done after sowing of maize and millet, and on stubble after harvesting. It can be established that less degree of compaction was characteristic to the soil of the plots treated for several years with the soil conditioner during the vegetation period than in case of untreated plots. Higher CO₂-emission values were observed on the plots treated for several years than on the control plots. This effect can’t be established in case of soil conditioners used for first time in this year.