Costa Rica, Biologischer Korridor in der Golfo Dulce Region, La Gamba Erfahrungen in der gezielten Anwendung von Stickstoff sammelnden ein-, zwei- oder mehrjährigen Pflanzenarten – zur optimierten Wachstumsförderung ausgewählter Arten

The master thesis is being carried out as part of the project COBIGA - The Biological Corridor in La Gamba (Biological Corridor La Gamba). The aim of this project is to connect the forests of the lowlands with those of the highlands and at the same time to develop the region sustainably. The Corcovado National Park and the Piedras Blancas National Park are connected by the Golfo Dulce Forest Reserve, which acts as a (still inadequate) green bridge. Some of the Golfo Dulce Forest Reserve properties are still privately owned by farmers. Therefore, one goal of the project is to encourage these landowners towards sustainable agriculture using organic fertilizers and local nitrogen-fixing plants. This would improve and support the migration between flora and fauna between the two national parks. The findings of the scientific work in this project should help to advance the development of an intact green bridge.
Due to their energy-intensive production, synthetic N-fertilizers have a strong negative climate footprint and are therefore heavily criticized for being non sustainable. Organic fertilizers are an important alternative if used properly. The use of organic fertilizers, but also their production can be enhanced by using plant species associated with N-fixing organisms.

The data of the master thesis which will be evaluated is going to be collected in Costa Rica in the Golfo Dulce Region. To do so, farmers in the region and scientific experts will be interviewed about their knowledge and experience in the production of organic fertilizers deriving from plant materials like leaves, barks, stems and branches. These interviews will be done with a standardised survey.
In addition, a practical experiment based on the findings of the interviews of the farmers and scientific experts will be carried out in the tropical station "La Gamba".
The practical experiment will be conducted on the tropical station on an already prepared composting site. There, different parts of plant organs (branches, leaves, barks, roots etc.) deriving from plants which benefit from N fixing bacteria in form of symbiosis, associations or with free living bacteria, will be composted mixed or separately and banana residues will be added.  The substrate will be turned over a few times per week to ensure even rotting throughout the compost piles and to prevent overheating of the inner core of the composts.
The data (e.g. temperature) will be recorded daily throughout at least two months. Samples will be sent for sequencing to determine bacterial communities inside the composts. The analysis of the mineral composition of the composts will be outsourced and included in the thesis.
The interviews will be conducted in the first two months of my stay and the practical experiments will follow right after the surveys with a duration of another two months, leading to a total research time of four months.

The findings of the master thesis will be used (together with findings of other master theses) to hold workshops on the tropical station and train local farmers and students to improve natural habitats. Also, with this project we want to encourage farmers to turn to sustainable agriculture, without relying on external supplements to cultivate their fields.