Terra Negra

Community garden

Introduction

The Terra Negra activity is an innovative composting process that combines organic matter from biodegradable waste with charcoal, resulting in a highly fertile and stable compost. The process begins with the collection of organic waste, such as kitchen residues, pruning clippings and other biodegradable materials, which are carefully sorted and sent for controlled decomposition. To this organic matrix, charcoal is added, an element characterised by a highly porous structure, capable of retaining nutrients and improving compost quality.
During the composting process, the presence of charcoal promotes more efficient decomposition, limiting the formation of unpleasant odours and preventing the leaching of liquid organic substances that could contaminate soil and groundwater. The end result is an enriched compost, known as Terra Negra, which is a true natural soil conditioner. This product is characterised by its ability to improve the quality of the soil, increasing its fertility and moisture retention capacity, thus reducing the need for chemical fertilisers.

Activity Topic

Sustainability, environmental regeneration.

Organisation

Tigergarten

Legal Status

Non-Profit Organisation

Year of Establishment

2012

Location

Vienna Tigerpark 8th disctrict

The Tighergarden urban vegetable garden is located in a public square in Vienna, in an area dedicated to community initiatives including green spaces and children’s play areas. With a surface area of approximately 170 square metres, comparable to that of an average-sized flat, this garden is a concrete example of participatory urban agriculture. The area, which is publicly owned, is managed thanks to the collaboration between citizens and the municipal administration, with the latter taking care of the maintenance of the hedges and larger trees, as well as ensuring the water supply for irrigating the crops.

The vegetable garden is organised in 19 raised containers, divided among several participants with the aim of involving as many people as possible in the care and cultivation of vegetables and flowers. This distribution encourages active community participation and makes the garden a social gathering place where citizens can share knowledge and experiences related to sustainable cultivation. In addition, some spaces are specifically designated for inclusive activities for people with disabilities, allowing them to experience the therapeutic benefits of contact with nature.

An integral part of the project is an area dedicated to composting, where organic matter from both the waste produced within the garden and the waste contributed by citizens of the neighbourhood is treated. This system encourages a circular approach to the management of organic waste, turning it into a useful resource for improving soil fertility and reducing waste.

Activity Description

Aims and Outcomes

Composting with the production of Terra Negra in community gardens, such as the Tighergarden, meets several objectives related to environmental sustainability and circular resource management. Being located in a public square, this garden is developed through raised wooden pots, which makes it essential to self-produce fertile and nutrient-rich soil to ensure healthy plant growth without having to resort to chemical fertilisers. The first objective of Terra Negra’s integration is therefore to reduce environmental impact by promoting a self-sufficient soil fertilisation system. Through composting, organic waste matter – both that produced internally by the gardens and that contributed by citizens – is transformed into a natural soil conditioner capable of enriching the soil and improving its structure. This process reduces the amount of organic waste going to disposal and at the same time returns essential nutrients to the soil. Short-term results include improved quality of the growing medium, increased moisture-holding capacity in the pots and optimised organic waste management. In addition, compost enriched with charcoal helps to limit the formation of unpleasant odours, improving the usability of the shared space. In the long run, the constant use of Terra Negra leads to an improvement in soil fertility and its ability to regenerate, reducing the need for external fertilisers and promoting a more sustainable model of urban agriculture. In addition, the spread of composting practices encourages the local community to develop greater environmental awareness, helping to build a more resilient and participatory urban ecosystem

Implementation Steps

The composting activity with Terra Negra production takes place in a specific area of the Tigergarten urban garden, where the treatment of organic matter is managed through a controlled and sustainable process. This area does not only process the waste produced within the garden, but also welcomes the active contribution of local citizens, who can bring in their organic waste, thus contributing to a community and circular recycling system. The composting process follows several stages to guarantee the quality of the final product. The first phase consists of collecting and sorting organic materials, which include fruit and vegetable scraps, coffee grounds, dry leaves and other biodegradable residues. Once collected, this material is placed in dedicated heaps or containers, where the natural decomposition process begins. One of the special features of the Terra Negra method is the addition of charcoal, a key element that gives the compost its characteristic dark colour and improves its quality. Due to its porous structure, charcoal plays a key role in nutrient and moisture retention, preventing the release of volatile substances that could generate unpleasant odours. It also promotes a more stable and rapid composting process, improving the soil’s ability to retain carbon and thus contributing to the reduction of CO₂ emissions. During the maturation process, which can last several weeks or months depending on environmental conditions, the organic material is gradually transformed into a humus-rich compost, ideal for enriching the substrate of vegetable garden pots and improving plant growth. The management of this activity is shared between the participants of the community garden, who monitor the proper aeration and moisture of the compost, ensuring that the process runs efficiently. The integration of Terra Negra into the garden’s production cycle not only ensures a fertile and natural compost, but also represents a model of urban circular economy, in which waste is transformed into a resource, fostering ecological awareness and active community involvement.

Advantages and Benefits

The integration of the Terra Negra composting practice within the Tigergarten urban garden offers numerous environmental, social and economic benefits. One of the key elements of this activity is its ability to optimise the resources available within an urban space, reducing fertiliser purchase costs and improving the self-sufficiency of the growing system. On-site compost production also reduces the transport and disposal of organic waste, cutting CO₂ emissions and contributing to a more sustainable waste management model. From a social point of view, composting actively involves community members, fostering collaboration between citizens and strengthening their sense of belonging. The possibility of delivering organic waste transforms the garden into a reference point for the area, stimulating participation and ecological awareness. The activity also encourages social mixing, creating opportunities for interaction between people of different ages and backgrounds, including children, the elderly and people with disabilities.

Furthermore, the presence of charcoal in the compost improves soil quality, making the practice innovative and effective in the long term.

Required Competences and Skills

in order to ensure a proper balance between compostable materials and charcoal. It is important to be able to recognise which organic waste is suitable for the process and in what proportion it should be mixed with charcoal in order to obtain a high-quality compost, free of unpleasant odours and rich in nutrients. In addition to technical skills, communication and awareness-raising skills are also essential. Since the activity involves community involvement, it is necessary to be able to explain clearly and effectively how to dispose of organic waste, educating citizens on proper composting practices. At the same time, it is important to convey knowledge about the use of the compost produced, explaining its benefits for the soil and plants, so as to encourage its use in the garden and other urban green areas. Finally, good organisational and collective management skills facilitate the coordination of activities, ensuring the maintenance of composting and the constant involvement of the community in the project.

Evaluation

The evaluation of the results of the Terra Negra composting activity is mainly based on the ability of the compost produced to ensure effective cultivation without the use of chemical fertilisers. The quality of the compost is measured by the growth and health of the horticultural and floricultural plants inside the wooden containers, verifying that the substrate is sufficiently rich in nutrients to support the growing cycle. Fertile, well-structured soil allows plants to develop healthily, with good yield and resistance to environmental stress. In addition to the agronomic aspects, the evaluation also takes into account the dissemination of organic material recycling techniques among the participants and citizens involved. Composting thus becomes not only a method to improve the soil, but also an educational and environmental awareness tool, helping to spread good organic waste management practices.

Conclusions

The opportunity granted by the City of Vienna to the Tigergarten association to use an area of approximately 170 square metres within the square of the same name for the creation of a small urban garden has allowed the development of interesting space management and optimisation techniques. In particular, the composting corner, in which the Terra Negra technique is applied, allows the association to make itself independent of the procurement of compost and mineral substances necessary for growing plants in the raised boxes. The practice ensures a fertile substrate for plant growth and encourages the dissemination of organic matter reuse and recycling techniques also in an urban context. The possibility of applying these methods in a city environment allows the community to be made aware of the importance of proper organic waste management, encouraging good composting practices and helping to develop greater environmental awareness.

Advice / Recommendation

The advice is to spread the Terra Negra composting technique more widely to citizens