Arboretum’s Hunnewell Interns investigate soil health

by Jon Hetman, Director of External Relations & Communications

October 8, 2015

Hunnewell Interns 2015

Arboretum’s Hunnewell Interns investigate soil health

The 2015 Hunnewell Interns

The 2015 Hunnewell Interns

This summer, the Arboretum hosted an exceptionally-driven and bright group of trainees participating in the Isabella Welles Hunnewell Internship Program. The program offers students of horticulture and the plant sciences the opportunity to work in the Arboretum’s historic landscape with its world-renowned scientific collection of trees and shrubs, under the expert guidance of staff in curation and horticulture. Interns gain hands-on work experience and participate in educational trainings and field trips, and to gain a broad sense of professional opportunities at a public garden. Interns also work together to address a real collections or landscape management issue as a collaborative component of the program.

The roots of an arboretum plant.

The roots of an arboretum plant.

This year’s cohort focused on a project affecting every plant in the Arboretum’s collection: an analysis of soil health. Interns were tasked with four main project objectives: (1) review and compile information on past soil work at the Arboretum, (2) create a holistic and systematic protocol for the soil testing (where, what, how), (3) implement the initial phase of the sampling protocol, and (4) analyze results and develop recommendations of short- and long-term actions to improve plant and soil health. Working in teams alongside Horticulture Department staff and Living Collections managers, interns developed a sampling protocol and tested 92 prioritized areas of the landscape. The samples were sent to the University of Massachusetts Soil and Plant Tissue Testing Laboratory for pH and nutrient analysis and to the Woods End Laboratories in Mt. Vernon, Maine to investigate the organic matter levels and biological activity.

A soil probe that interns used to collect samples of Arboretum soil.

A soil probe that interns used to collect samples of Arboretum soil.

Soil test results were analyzed and interpreted by interns to develop their recommendations for improving plant health at the Arboretum. The most significant of their findings was a low pH level for soil across the Arboretum. Low pH levels affect the amount of macronutrients – nitrogen, phosphorus, potassium, sulfur, calcium, magnesium – that are available to plants for growth. Based on these findings, the interns recommended the application of soil liming material over the next few years to steadily increase the pH levels across the collections. The recommendations also took note of other soil characteristics and management practices that affect plant growth, including soil compaction management, mulching and compacting, and use of cover crops to increase microbial activity and pore space.

The field experiences and collaborative project carried out by this year’s Hunnewell Interns provided hands-on experience useful in their chosen fields. “The completion of this project represents one of the most significant group project initiatives ever undertaken as part of the Hunnewell Internship Program,” noted Andrew Gapinski, Manager of Horticulture and coordinator of the Hunnewell Internship Program. “Their findings and recommendations set the framework for a renewed focus on the health of our soils, and in turn, the quality of care given to our collections.”

 

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