Soils differ substantially in fertility and hence in their suitability for intensive agriculture - especially traditional and low-input forms of intensive agriculture. Often soil fertility and the suite of soil properties and processes that are associated with it change abruptly in space, despite gradual and continuous changes in the factors that influence soil fertility (for example rainfall and soil age). This research models the causes and evaluates the consequences of abrupt changes in soils, and explores their implications for the functioning of terrestrial ecosystems under both natural and agricultural conditions. It builds on an extensive data base of soils from the Hawaiian Islands that includes large differences in the factors that control soils (for example rainfall from < 200 mm/yr to > 4000 mm/yr, soil age from a few hundred to several million years); this data base includes very clear examples of thresholds in soil properties and processes. In addition, it draws upon a detailed analysis of the distribution and dynamics of Hawaiian agriculture prior to European contact. The modeling effort will iterate between fundamental models of soil developmental processes and this detailed information, seeking to determine how much detail is necessary to model the development of abrupt changes in soils and the regions between them where soil properties are relatively consistent. It will test those models with newly collected soils information in and around pre-contact agricultural systems in Hawaii, and on soils formed from different types of rock in New Zealand.
The project will provide fundamental information on the processes that underlie soil fertility, and how they shaped the distribution of intensive agricultural systems in the past (and could contribute to low-input systems today and in the future). Carrying out this research will require integrating information from ecology, soil science, hydrology, geochemistry, and anthropology; hence it will contribute to the conceptual and practical unification of disparate disciplines. It will support two post-doctoral fellows and several undergraduate students --- and those students and postdoctoral fellows will learn how to integrate a broad array of research fields. Finally, this project is closely aligned with ongoing efforts by Native Hawaiian organizations and institutions to understand and to restore the traditional pre-contact agricultural systems of Hawaii, for educational and cultural purposes, and also to learn what those systems can contribute to present and future agricultural sustainability.
