Effect of recycled phosphorus and nitrogen blend fertilizers on the growth of viola (Viola cornuta L.)

A.A. Robles-Aguilar, O. Grunert, E. Meers, N.D. Jablonowski
Viola cornuta L. is an ornamental plant highly demanded in horticulture. It is becoming more and more critical for greenhouse growers to focus on sustainable production to enhance plant quality, reducing negative environmental impacts. Therefore, assessing the effect of recycled P and N sources on the growth and quality of viola could become very useful for producers and consumers. This experiment aimed to determine the optimal fertiliser composition to grow viola using recovered fertilizer products. The effect of applying the recovered products as fertilizers on the growth of viola was analyzed in a greenhouse trial under controlled conditions at the Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, Germany. Well rooted viola plugs grew in a standard peat-based growing medium with a well-known fertilizer composition used by the growing media industry (PGMIX14-16-18). Using recycled sources of P and N (struvite and potassium struvite, ammonium sulfate and ammonium nitrate), 15 fertilizer combinations were prepared and tested. Two controls were used: i) a substrate without fertilizer and ii) a slow-release commercial fertilizer (Osmocote 15+9+11+2 MgO and trace elements). Triple-superphosphate (TSP) and potassium sulfate (K2SO4) were used together with the recycled nutrients to fulfil the major macronutrient requirements of viola. Plants treated with blends containing the recovered ammonium nitrate showed healthy growth and optimal plant N concentrations. In contrast, combinations using the recovered ammonium-sulfate resulted in an unacceptable increase in electrical conductivity affecting the germination and growth of the plants. The combination of struvite recovered ammonium nitrate and recovered potassium-sulfate has the best chemical composition with non-significant differences in the biomass from the positive controls. Our results indicate that fertilizer blends with recovered fertilizer products (P as struvite and N as ammonium-nitrate) can substitute the use of mineral fertilizer blends to grow ornamental plant species as viola.
Robles-Aguilar, A.A., Grunert, O., Meers, E. and Jablonowski, N.D. (2021). Effect of recycled phosphorus and nitrogen blend fertilizers on the growth of viola (Viola cornuta L.). Acta Hortic. 1317, 223-230
DOI: 10.17660/ActaHortic.2021.1317.25
struvite, ammonium nitrate, ammonium sulfate, recovered nutrients, greenhouse flowers

Acta Horticulturae