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Digging in the Dirt

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Nicole Gordon

Geography student delves into ancient Peruvian terraces

Blaise Murphy in the Andagua Valley of southern Peru

Blaise Murphy has always liked digging in the dirt. As a master’s candidate in the Department of Geography & the Environment, she spent last summer in the Peruvian Andes doing exactly that.

Murphy is researching the impact of land management on agricultural soils in the Andagua Valley of southern Peru. Her broad goal is to shine light on the abandonment and reconstruction of agricultural terraces and how this affects soils, either positively or negatively, for future cultivation.

“When I told local people about my project, they were very excited,” she says. “As farmers, they have a big interest in their soils and any information about it.”

The remarkably steep slopes of the Andes forced the Incas and civilizations before them to devise innovative ways to harvest agriculture. These early farmers cut terraces and canals into the mountainsides to grow crops such as corn, potatoes, and quinoa. A system of terraces measuring nearly 1 million hectares covered Peru at the height of the Incan empire in the 1400s. After the Spanish invasion, the system fell into disarray.

More recently, a renewed interest in traditional agricultural methods has led farmers to begin rebuilding the terraces and canals. In the Andagua Valley, a community of farmers has been cultivating reconstructed terraces for several decades now.

When terraces aren’t maintained structurally over time, they can collapse from erosion. In turn, nutrients may be washed from the topsoil. Murphy is comparing the nutrient profiles of soils in the newly cultivated terraces to those of abandoned and continuously cultivated terraces in the area.

“Land abandonment is a huge issue all over the world, with erosion happening at incredible rates,” Murphy says, citing climate change and urbanization as two of the drivers. “This research could help show how abandonment negatively affects soils.”

In the field, Murphy analyzed the texture, color, aspect, elevation, moisture, and other characteristics of soils in different terraces. She brought 90 soil samples back to her lab at DU, where she's measuring them for a range of nutrient contents and acidity.

She’s also collaborating with a team of archaeologists who are undertaking a systematic survey of the Andagua Valley, which contains archaeological sites ranging from pre-Inca periods to the more recent past. She expects the results to help her interpret her work within an archaeological and anthropological context.

Peru’s Colca Valley, a well-known tourist destination next door to Andagua, has been studied quite thoroughly by geographers, archaeologists, and others. “There’s not much information on the Andagua Valley as it’s very remote, so we’re hoping to contribute to that,” Murphy says.

Murphy’s path to a master’s degree in geography at DU allows her to combine multiple interests.

“I’ve always liked soil and found myself attracted to physical geography, but I still wanted a connection to people,” she says.

Her summer in a small, isolated valley gave her the opportunity to interact with local farmers and even help harvest potatoes herself.

“What better way to spend a summer than hiking around in the Andes while doing research?”