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Written by Emilie Wood, Writer and Event Coordinator, UCSB Living Lab

Did you know that soil tells a story? It can take you back hundreds of years and show how ancient people used the land, where they had fires, and how they grew food. Dr. Oliver Chadwick is a soil scientist and a professor at UCSB—and he shares some amazing stories about soils he has encountered, as well as cautionary stories about current soil. Dr. Chadwick begins, “in today’s world, people don’t really worry about the basic fertility of the soil because, in modern agriculture and gardening, you can throw on a handful of synthetic fertilizers and grow bigger plants. But it is important to keep track of the underlying state of affairs of the soil.” His concern about the treatment of soil in modern agriculture is rooted in his understanding of past soils and the fundamental differences between them.
Dr. Chadwick’s most recent soil story takes place on the Hawaiian Islands, where his research group is working to understand how Polynesians adapted to the new environments they encountered on every island before the innovations of the industrial agriculture revolution. Polynesians in Hawaii created the most complex society in the Pacific Islands, and there was no sign of cultural decline at the time of European conquest. Anthropologists working with Dr. Chadwick explain that in order for this complex hierarchical society to form, there had to be food production in excess of basic societal requirements. This excess allowed certain individuals to move away from subsistence farming into cultural jobs, like warriors, priests, and government officials. These people were no longer producing any food themselves, yet they were definitely still eating. Dr. Chadwick’s group is working to understand what is unique about the physical and chemical makeup of the Hawaiian Islands that made it possible for the production of excess food.
In order to begin answering this complicated question, they started from the ground up. Dr. Chadwick, the soil specialist, began research into the chemical and physical characteristics of the different soils on the island to understand why food production was so successful on the Hawaiian Islands, as compared to others in the Pacific. Hawaii is very large, compared to many small isolated Pacific islands, and the volcanic eruptions are relatively recent, leading to highly nutritious soils. Also, the relatively large land area allows heterogeneity in soil composition, so one part of the island may have moist and clayey soil, while another area might have drier, sandy soil. This allowed different crops to succeed in different areas of the island.
Dr. Chadwick is able to evaluate soil samples to determine how the soil was used and if it had been modified to enhance agriculture production. Although their farming did not use modern equipment and synthetic fertilizers, the Polynesians still modified their soil and had an inherent understanding of soil properties. Dr. Chadwick found evidence of mulching, irrigation channels, and charcoal in the soil. These varied technologies and soil amendments give us insight into their farming knowledge and help to explain their success in utilizing the diverse soil composition on the island.
Was the Polynesian approach to agriculture in Hawaii sustainable in the face of continuing population growth? Dr. Chadwick believes the Polynesians were beginning to convert marginal lands into croplands at the time the Europeans arrived, which would have further increased their food production, supporting the growing, complex society. However, in the long run, Dr. Chadwick does not believe this island’s society would have been a sustainable model. There are certain physical constraints to living on an island, as there is only so much land to utilize. The reason why the Polynesians settled on so many of the Pacific islands was because they had the expertise to find new islands as their populations grew. Hawaii had not yet run into a population problem, though their increased population growth was beginning to stress the fertile soil, as evidenced by the increased use of marginal lands with less productive soil. The long-term fate of the Polynesians on the Hawaiian Islands was cut short by the arrival of Europeans, and, more recently, the islands’ soils have been degraded with the introduction of more modern agriculture practices.
Soil everywhere has stories to tell about the past, but what will the soil of today tell the scientists of the future? With our intensive agriculture practices and the general population’s lack of understanding about the soil we exploit to feed an ever-growing population, it is possible that future researchers will find a story without a happy ending. Dr. Chadwick explains, “current soil use and modern erosion of the land way outstrips the rate of soil formation, imposing very intensive demands on a resource we entirely depend on, yet do not maintain.” By using soil as a time machine, we know what soils of the past look like. It is time to use these healthy soils of the past as a model in restoring the quality of our soil today. Dr. Chadwick cautions, “the entire human society is built on food production, soil is the base of food production, and we are using this resource for agriculture at an unsustainable pace.”