Urban Gardening Analysis of the Ljubljana Case study
We asked different socioeconomic questions to 127 gardeners all over the Ljubljana Municipality. The average gardener in Ljubljana is female, 58 years old, with College, BSc or MSc education and retired or self-employed. They have an average household income around 1,000-1,500 EUR with a budget earmarked for food supply of around 200-400 EUR. They cultivate hired garden plots away on private land or home gardens and dedicate between 4 to 6 hours a week gardening and use homemade compost as their main source of fertiliser. Their knowledge about gardening comes from personal observation, other gardeners or books – they are not professionals. Their main motivation for gardening is the procurement of safer, healthier foods, recreation and relaxation. More than 50% of them cover over 50% of their vegetable needs. More than 80% of gardens reported using the production for their own needs, however 70% of them also donate surpluses. Gardeners say that their food is healthier and tastier than the one from stores. Gardening also contributes to better interpersonal relationships and strengthens the integration of the people in the community.
All 127 gardeners estimated their yearly production costs (seeds, seedling plants, fertilisers, plant protection, etc.). By multiplying the yield of the five most common harvested vegetables and their average retail price, we estimated that the production was valued at 3.69 EUR/m2. By deducting the production cost (1.27 EUR/m2) from this value, we estimated that the average gross margin for food production in the MOL was 2.42 EUR/m2. The approximate expected economic impact of urban gardening on the vegetable supply chain in the city of Ljubljana expressed as the gross margin of the areas currently dedicated for allotment gardens (45.89 ha) is 1,100,000 EUR/year and of the areas identified by aerial images (158 ha) is 3,800,000 EUR/year.
Soil samples were collected from 186 interviewed gardeners with 193 plots in the Ljubljana Metropolitan Region (Slovenia) to analyse the content of phosphorus, potassium, organic matter and heavy metals. The results for phosphorus, potassium and organic matter show that gardeners often over-fertilise their plots (although with organic fertilisers). This does not negatively impact too much on the environment but it is not so good for plant resistance (unbalance in soil minerals) and is at least unnecessary causing additional costs. Concentrations of cadmium, lead and zinc are below the limit values mainly, which are as follows: Cd = 1 mg/kg of dry soil; Pb = 85 mg/kg of dry soil; Zn = 200 mg/kg of dry soil, although in some cases they can exceed them. This means that in some cases soil fertility could be reduced and there is possibly some risk from vegetable consumption from these locations. Interviewed gardeners were informed about the results of soil analyses and warned about soil quality if necessary. Although 95% of gardeners report that they cultivate their gardens in organic, integrated or permaculture ways, only 5% of them have made soil tests and less that 1% has knowledge about heavy metals in their gardens’ soils.