1. Solid fraction of separated digestate as soil improver: implications for soil fertility and carbon sequestration.
- Author
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Egene, Caleb Elijah, Sigurnjak, Ivona, Regelink, Inge C., Schoumans, Oscar F., Adani, Fabrizio, Michels, Evi, Sleutel, Steven, Tack, Filip M. G., and Meers, Erik
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CARBON sequestration ,SOIL fertility ,HUMUS ,SANDY loam soils ,CARBON in soils ,SOILS - Abstract
Purpose: This study investigated the C and N mineralisation potential of solid fractions (SFs) from co-digestated pig manure after P-stripping (P-POOR SF) in comparison with P-rich SFs, as a means to estimate their organic matter stability in soil. Compost (COMP) and biochar (BCHR) (made from P-POOR SF) were also included in the study as reference biosolids. Methods: The SFs were incubated in a sandy-loam soil under moist conditions to determine production of CO
2 and mineral N. At specified intervals, CO2 evolution in the mixtures was measured via the alkali trap method and titration over a period of 81 days, while mineral N was measured using a flow analyser after KCl extraction over a period of 112 days. Results: The various SFs showed similar patterns of C mineralisation (15–26% of added total C in 81 days) that were clearly higher than for COMP and BCHR (6% and 7%, respectively). Temporary N immobilisation was observed in biosolids with a high C/N ratio. The effective organic matter (EOM) of the SFs was calculated based on the C mineralisation data and varied between 130 and 369 kg Mg−1 . Conclusions: The SF with a reduced P content had a high EOM/P ratio which is beneficial in areas where P status of the soil is already high. Moreover, the N mineralisation patterns confirm that a high C/N ratio may also reduce risks for N leaching due to temporary N immobilisation. [ABSTRACT FROM AUTHOR]- Published
- 2021
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