Title : Vermicompost derived liquid organic fertilizers as effective replacements for chemical fertilizers in spinach production
Abstract:
There is an increasing demand for environmentally friendly organic fertilizers that can replace conventional chemical
fertilizers for organic agricultural production. A pot experiment was conducted in growth rooms to evaluate the
performance of four different liquid organic fertilizers - Cermaq 1 (T1), Cermaq 2 (T2), Mjøsa (T3), and HRA (T4).
These were extracted from vermicompost of fish sludge (Cermaq), cow manure (Mjøsa) and food waste (HRA)
digestates from biogas reactors. The objective of the experiments was to evaluate the potential of stable liquid
organic fertilizers from vermicompost to replace conventional chemical fertilizer (T5) using spinach (Spinacia
oleracea L.) as a test plant production. The experiment was conducted in growth chambers of Edelmark (a private
research organisation) and the Norwegian University of Life Sciences (NMBU) by employing a completely
randomized experimental design with three replications per treatment. The growing chamber at Edelmark was a
simple greenhouse that relied on natural temperature and light conditions. In contrast, the growth chamber at
NMBU was maintained at a constant temperature of 16?°C, with light provided by Heliospectra LED lamps at an
intensity of 186 µmol?m?²?s?¹. Plant height, fresh weight and dry biomass of shoots and roots were measured and
analysed using ANOVA. The results showed no significant differences in plant height among the treatments (F = 2, 1
α= 0, 05). The yield obtained from mineral fertilization (T5) was significant different, (F = 27, 02 α= 0, 05) from the
yields obtained by the fertilization of organic fertilizers of vermicompost from cow manure (T3) and food waste
digestate (T4). However no significant difference was observed in in fresh and dry matter weights of spinach plants treated with mineral fertilization (T5) and liquid organic fertilizer of digestate of fish sludges, T1 and T2. The organic fertilizers from digestates of fish sludge (Cermaq 1 and 2) showed superior or equivalent performance to mineral fertilizer across all measured parameters, making it the most viable replacement option. The experiment has
demonstrated that there is a potential to develop stable liquid organic fertilizers from vermicompost, which
effectively can replace traditional mineral fertilizers without compromising spinach growth and yield. Such research
results will be valuable for further investigation of the development of sustainable and circular liquid organic
fertilizers that fully can replace mineral fertilizers in horticultural production systems without compromising yield.
