The Chemical Composition of Biogas Digestates Determines Their Effect on Soil Microbial Activity

Kerstin Nielsen, Christina-Luise Roß, Marieke Hoffmann, Andreas Muskolus, Frank Ellmer and Timo Kautz
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Kerstin Nielsen: Institute for Agricultural and Urban Ecological Projects affiliated to Berlin Humboldt University, Philippstraße 13, 10115 Berlin, Germany
Christina-Luise Roß: Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, Faculty of Life Sciences, Berlin Humboldt University, Invalidenstraße 42, 10115 Berlin, Germany
Marieke Hoffmann: Deutsche Umwelthilfe E.V., Hackescher Markt 4, 10178 Berlin, Germany
Andreas Muskolus: Institute for Agricultural and Urban Ecological Projects affiliated to Berlin Humboldt University, Philippstraße 13, 10115 Berlin, Germany
Frank Ellmer: Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, Faculty of Life Sciences, Berlin Humboldt University, Invalidenstraße 42, 10115 Berlin, Germany
Timo Kautz: Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, Faculty of Life Sciences, Berlin Humboldt University, Invalidenstraße 42, 10115 Berlin, Germany

Agriculture, 2020, vol. 10, issue 6, 1-20

Abstract: Digestates are commonly used as organic inputs in agriculture. This study aimed to answer four questions: (1) What are the immediate and longer-term impacts of digestates on soil microbial activity?; (2) How much of the digestates’ carbon is mineralized within the first months? (3) How do the nitrogen, lignin, cellulose, and hemicellulose contents of digestates influence microbial activity and carbon mineralization? (4) How does the soil type influence mineralization? To investigate this, dehydrogenase activity (DHA) was measured in a field trial and in laboratory experiments with five digestates (DGs), cattle slurry, and cattle manure. DHA measurements were supplemented with soil respiration experiments using two different soils. DHA was significantly increased by all organic inputs, but decreased back to the control level within seven months under field conditions. Twenty percent to 44% of the organic carbon (C org ) in the digestates was converted to CO 2 after 178 days. Soil respiration was significantly negatively correlated to lignin content (r = −0.82, p < 0.01) and not correlated to nitrogen, cellulose, or hemicellulose content. On the basis of equal carbon application, slurry promoted soil respiration and DHA more strongly than digestates in the short term.

Keywords: dehydrogenase activity; soil respiration; separation; biogas residues; digestates (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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