Analyses on
tomato biomass were done by Labor fuer Boden
und Umweltanalytik in Zurich using Kjehldahl,
photometry, Atomic Absorption Spectroscopy
(AAS) or Inductively coupled plasma (ICP). For
cucumbers and aubergines, values for dry matter
and Nitrogen, Phosphorus and Potassium (NPK)
content were used from literature [24,25].