Calculating the effect of intensive use of urban organic waste on soil concentrations of potentially toxic elements in a peri‑urban agriculture context in Norway2025
Recycling nutrients and organic matter available as waste in urban areas may close nutrient gaps and improve soil quality, but the concentrations of potentially toxic elements (PTEs) are commonly higher than in mineral fertilisers. How quickly may the limits for soil quality be exceeded, and for which elements, if such materials are applied intensively? For a rough answer to this question, we used soil data from ten case farms near Oslo and Bergen (Norway) to estimate how PTE concentrations increased when the demand for nitrogen (N), phosphorus (P) and potassium (K) in a theoretical carrot crop produced every year was covered by compost or digestate from source-separated food waste, or composted garden waste, compared with manure from horses and poultry which are often kept in peri-urban areas.
With the intensive fertilisation assumed here, the Norwegian soil quality limits for PTEs were reached within 20–85 years, and faster for soil with more organic matter since regulatory limits set by weight discriminate soils with low bulk density. The limits were reached first for Cu and Zn, which are both essential micronutrients for crop plants. The concentrations of macronutrients in the urban waste-based fertilisers were not well balanced. Rates covering the K demand would lead to high surpluses of P and N. In peri-urban vegetable growing, high applications of compost are not unusual, but more balanced fertilisation is required.
The Norwegian regulations for PTEs in organic soil amendments and agricultural soil are stricter than in the EU, and do not support recycling of organic matter and nutrients from urban waste. Many materials which can only be applied with restricted amounts to Norwegian agricultural soil, may be applied according to crop demand in the EU. Growers utilising urban waste-based fertilisers intensively should monitor the soil regularly, including PTE analyses. Soil sampling should occur on fixed sampling points to reveal changes in concentrations over time. Norwegian authorities should consider a revision of the organic fertiliser regulation to support recycling of valuable organic materials. There is a need for more data on the PTE concentrations in agricultural soil and organic fertiliser materials.
Calculating the effect of intensive use of urban organic waste on soil concentrations of potentially toxic elements in a peri-urban agriculture context in Norway2024
Background: Recycling nutrients and organic matter available as waste in urban areas may close nutrient gaps and improve soil quality, but the concentrations of potentially toxic elements (PTEs) are commonly higher than in mineral fertilisers. How quickly may the limits for soil quality be exceeded, and for which elements, if such materials are applied intensively? For a rough answer to this question, we used soil data from ten case farms near Oslo and Bergen (Norway) to estimate how PTE concentrations increased when the demand for nitrogen (N), phosphorus (P) and potassium (K) in a theoretical carrot crop produced every year was covered by compost or digestate from source‑separated food waste, or composted garden waste, compared with manure from horses and poultry which are often kept in peri‑urban areas.
Results: With the intensive fertilisation assumed here, the Norwegian soil quality limits for PTEs were reached within 20–85 years, and faster for soil with more organic matter since regulatory limits set by weight discriminate soils
with low bulk density. The limits were reached first for Cu and Zn, which are both essential micronutrients for crop
plants. The concentrations of macronutrients in the urban waste‑based fertilisers were not well balanced. Rates
covering the K demand would lead to high surpluses of P and N. In peri‑urban vegetable growing, high applications
of compost are not unusual, but more balanced fertilisation is required.
Conclusions: The Norwegian regulations for PTEs in organic soil amendments and agricultural soil are stricter
than in the EU, and do not support recycling of organic matter and nutrients from urban waste. Many materials
which can only be applied with restricted amounts to Norwegian agricultural soil, may be applied according to crop
demand in the EU. Growers utilising urban waste‑based fertilisers intensively should monitor the soil regularly, including PTE analyses. Soil sampling should occur on fixed sampling points to reveal changes in concentrations over time. Norwegian authorities should consider a revision of the organic fertiliser regulation to support recycling of valuable organic materials. There is a need for more data on the PTE concentrations in agricultural soil and organic fertiliser materials. Keywords Cadmium, Copper, Zinc, Smallscale vegetable growing, Food wastes, Urban agriculture, Compost, Digestate
Bynær dyrking med resirkulert gjødsel?2023
Mange som dyrker grønnsaker til direkte salg er interessert i økologiske driftsmetoder. Det er mye organisk materiale tilgjengelig i byer og tettbygde strøk. Matrester og avfall fra hager og parker kan bli til både energi og gjødsel, som kan brukes i dyrking av grønnsaker i bynære strøk. Da får vi korte verdikjeder, men hva med innholdet av tungmetaller? Beregninger viser at grenseverdier i jord vil mettes først for kobber og sink, som også er viktige mikronæringsstoffer. for planter. Jordforbedringsmidler med høyt innhold av organisk materiale, som hage-park kompost og hestegjødsel, inneholder mer tungmetaller per kg tørrstoff enn fjørfegjødsel og utråtnet matavfall.
Insektsmøkk som gjødsel2021-05-21
Insektfrass ble undersøkt som gjødsel i kepaløk og rødbete og sammenlignet med pelletert hønsegjødsel hos en grønnsakdyrker i Ulvik. Det ble meravling for begge gjødselslagene sammenlignet med 0-ledd, noe høyere for hønsegjødsel.
