Research Topics
To achieve the objectives of the program nine research topics were initially defined. Research topics were multi/interdisciplinary in scope and were closely related to each other. These topics allowed to focus on the socially constructed nature of Terra Preta and to connect different time scales (through studies on palaeo-economy, palaeo-agronomy and ethno-ecology that link indigenous knowledge on resources with science-based management). In that way our understanding of the past provided not only an inspiration, but also the necessary knowledge for creating soils that allow sustainable and productive agriculture.
For more detailed information on the PhD theses that were developed from these topics, see People>PhD candidates and Publications>Theses.
1. Terra Preta, forest composition and forest dynamics
Forests in the Amazon area have often been considered as pristine, but many of these forests are less than a few hundred years old and bear traces of former human interventions. The human legacy can be seen in both the soils (Terra Preta) and in the vegetation (enrichment with fruit-bearing and other useful species such as palms for housing). This legacy has most likely resulted in different forest composition, structure and dynamics which are caused by and feed back to soil properties.
2. Institutional and policy aspects of Terra Preta (Nova) production, use and management
The use of commonly-owned natural resources does not always lead to a Tragedy of the Commons. Often such use is guided by various institutions that enable certain uses and prevent the full depletion of the resource. Both informal local institutions as well as formal juridical-bureaucratic ones play a role when traditional rules and modern bureaucracies interact. Institutions do not always prevent resource depletion, particularly when mixed rule systems create insecurity, unclear situations and misuse. Economic growth, illegal activities and/or population pressure may also go beyond the regulatory power of given institutions.
3 & 9. Farmers’ perception and actual use of the fertility of Terra Preta
Transformation of inherently infertile oxisols into highly productive Terra Preta by pre-Columbian civilizations has been linked with technological innovations resulting from increasing population pressure but also with nomadic patterns. These innovations were escorted by complex management systems of soils and plant resources in such a way that soil fertility was increased. As a consequence such soils are used for various purposes; but they also constitute a major cultural heritage. While the Brazilian laws aims to protect Terra Preta soils from other uses, these soils are currently being used for different purposes.
4. The creation of Terra Preta Nova
In Amazonia, anthropogenic soils with high fertility (Terra Preta, Terra Mulata) are of widespread occurrence. These soils are partly used for agricultural purposes.
5. Assessing the impact of Terra Preta Nova on carbon budgets
Terra Preta soils contain much higher amounts of carbon that other soils in the Amazon region and contribute thereby to carbon sequestration. The suggestion has been made to recreate such soils (Terra Preta Nova) where carbon sequestration can be combined with agricultural sustainability.
6. Looking into the palaeo-economic origin of Terra Preta
The abundance and high fertility of Terra Preta suggests that native populations were dense and characterized by sedentary settlement before the arrival of Europeans. Large sedentary populations indicate an extraordinary food production capacity. Building and maintaining Terra Preta must also have absorbed a substantial amount of labour.
7. Reconstructing the origin of Terra Preta – a mechanistic, stoichiometric nutrient balance approach
Attempts to understand the origin of Terra Preta (and thereby also the creation of Terra Preta Nova) suggest that neither charcoal alone nor mineral nutrients alone can raise the fertility of these soils sustainably. Interactions between the different components of the input are poorly understood.
8. Soil biota in Terra Preta soils
While soil physical and chemical properties of Terra Preta are fairly well known, soil biology is lagging behind. We hypothesize that soil biota play a crucial role in Terra Preta functioning, as Terra Preta soils have been characterised as ‘living soils’.