Scherer H.W. author Metker D.J. author Welp G. author text journal article 2011 We studied the long-term effect (about 45 years) of farmyard manure, sewage sludge and compost application in two increments on organic carbon (C_org), the amount (C_mic) and activity of the microbial biomass (soil respiration, dehydrogenase activity), total N content and N delivery of soils as compared to manuring with mineral fertilizers. The application of both increments of compost and the high sewage sludge application rate resulted in an increase in C_org while soils treated with both compost application rates and the high farmyard manure application rate showed a significant increase in C_mic. C_mic/C_org ranged between 1.7 and 3.3. Dehydrogenase activity and soil respiration were the greatest in the soil with the highest compost and farmyard manure application rates. Total soil N content was significantly higher in both compost treatments and in the treatment with the high sewage sludge application rate. This was accompanied by the highest N uptake of ryegrass. long-term field experiment; enzyme activity; microbial activity; N delivery; organic manure 10.17221/3283-PSE https://pse.agriculturejournals.cz/artkey/pse-201111-0004.php https://pse.agriculturejournals.cz/artkey/pse-201111-0004.php continuing 57 11 513 518 2011 12141178 periodical academic journal