Effects of mixed pulp mill sludges on crop yields and quality

Authors

• Sari Kinnula Department of Agricultural Sciences, University of Helsinki https://orcid.org/0000-0002-3264-9803
• Marjaana Toivonen Department of Agricultural Sciences, University of Helsinki; Finnish Environment Institute (SYKE) https://orcid.org/0000-0002-9215-8643
• Helena Soinne Natural Resources Institute Finland (Luke) http://orcid.org/0000-0002-7965-6496
• Juuso Joona Department of Agricultural Sciences, University of Helsinki
• Jukka Kivelä Department of Agricultural Sciences, University of Helsinki

DOI: https://doi.org/10.23986/afsci.95600

Keywords:

primary sludge, secondary sludge, organic fertiliser, soil amendment, recycled fertiliser, nutrient recycling

Abstract

There is a great need for sustainable fertilisers and soil amendments, as current fertilisation practices negatively
affect the environment. Pulp mill sludges (PMS) could provide a means to replace fertilisers made using non-
renewable resources while adding slowly decomposing organic material to the soil and utilising nutrients from the forest industry. This study tested the effects of composted and lime-stabilised mixed PMS (CPMS and LPMS) on wheat (Triticum aestivum) yields and residual effect on oat (Avena sativa) yields in the boreal region. A two-year field experiment included two CPMS and two LPMS treatments all with additional mineral fertilisation, a mineral fertiliser treatment, and a zero-control treatment. All the fertilisers increased yields. There were no differences in crop yields between CPMS, LPMS and mineral fertiliser treatments. However, some quality characteristics and nitrogen (N) uptake were lower with all or some PMS compared with mineral fertilisation. This result suggests that part of the mineral fertilisation for cereals could be replaced by using PMS, but more information on N mineralisation from sludges is needed.