Abstract

The use of dried digestate solids from biogas plants as organic fertilizers may be disadvantaged by considerable N losses during thermal treatment. Acidification can decrease NH3 emissions during drying, but little is known about the degradability and N release pattern of acidified and dried digestate solids. In a laboratory incubation, C mineralization and gross and net N mineralization from digestate solids subjected to acidification (to pH 5.5) and drying (70 or 160 degrees C) were monitored for 160 d at 15 degrees C. Gross N mineralization rates were determined using the N-15 isotopic pool dilution technique, and gross N transformation rates were calculated with the FLUAZ model. Irrespective of further treatment, acidified solids showed up to 50% reduced cumulative CO2-C respiration throughout the incubation and consequently decreased gross N mineralization rates compared with unacidified solids. Moreover, acidification of digestate solids delayed the nitrification dynamics during the first 3 wk of incubation. Throughout the experimental period, the acidified dried digestate solids had the highest inorganic N contents among all treatments. It was evident that acidification increased the stability of the organic matter and enhanced the availability of N on application to soil.

Published in

Soil Science Society of America Journal
2016, Volume: 80, number: 4, pages: 943-953
Publisher: SOIL SCI SOC AMER

UKÄ Subject classification

Soil Science


Publication identifier

DOI: https://doi.org/10.2136/sssaj2016.03.0059

Permanent link to this page (URI)

https://res.slu.se/id/publ/87473