On a sunny day in late winter, students from Manzo Elementary School helped harvest spinach, red-leaf lettuce, butter-leaf lettuce, Swiss chard, and mâche (also called lamb's lettuce). The students divvied up most of the harvest to bring home to their families.

The organic vegetable garden at Manzo, in Tucson, Arizona, is supported by four 4,500-liter (1,200-gallon) rainwater cisterns. It is fertilized between growing seasons with compost, made with food waste from the cafeteria.

In a few months, students will be harvesting vegetables not just from soil, but from water, too. This is part of a new aquaponics system set up at Manzo with the help of school counselor Moses Thompson.

"We have a 600-gallon tank for farming tilapia and veggies," he says. "It's a closed system—the fish fertilize the vegetables with their waste and the vegetables filter the waste to keep the water fresh."

Manzo Elementary is a neighborhood school in the Barrio Hollywood area of Tucson. Tucson lies in the heart of the Sonoran Desert in southern Arizona, a landscape freckled with cactus species, from the iconic saguaro to the misleadingly named teddy bear cholla. Less than 105 kilometers (65 miles) from the border with Mexico, the community of Barrio Hollywood is rich with Hispanic heritage and Spanish-speaking populations.

Thompson has worked at Manzo for six years. In his role as counselor, he integrates innovative outdoor learning methods. Gardens, native plant biomes, and other project-based schoolyard features provide an authentic context to teach and practice effective communication, problem-solving, and cooperation. Gardens also provide a tranquil environment for students experiencing anxiety.

"I use the therapeutic nature of gardening to deliver my counseling program," Thompson says. "Also, the habitats and gardens we build with students serve as the setting for individual and group counseling, and classroom guidance lessons."

When Thompson came to Manzo, these types of projects weren't in place. He gave new energy to a vision originally developed by Manzo physical education teacher Adrian Garcia—to develop a native-plants biome.

"The Sonoran Desert Biome was actually the first project where I began to incorporate horticulture and school counseling. When I started at Manzo over five years ago, the Biome was a fenced-in vacant lot filled with tumbleweeds and trash," says Thompson.

"With the support of the Manzo Student Council, we began performing rainwater-harvesting earthworks and installing native plants chosen to attract birds and pollinators. Slowly, I began using the space for counseling, which evolved into the primary system of garden maintenance.

"Another defining force in using the space for counseling was our first plant sponsor, Desert Survivors Native Plant Nursery here in Tucson. Desert Survivors uses horticulture therapy with adults to maintain the nursery, so they not only provided me with plants but also inspiration."

Thompson is a graduate of the National Park Service's Teacher to Ranger to Teacher (TRT) Program, which links national park units with teachers mostly from under-served school districts. In participating parks across the United States, selected teachers spend the summer working as park rangers, often living in the park. Then, during the school year, the teachers bring the parks "into" the classroom by giving lessons that draw on their summer experience.

Ethnobotany and Sustainable Schoolyards

Manzo's horticulture program also includes ethnobotany. Ethnobotany is the study of how plants are used in different cultures for food, medicine, rituals, clothing, or construction. The school's native vegetable garden, for instance, produces crops traditionally harvested by indigenous Native American tribes, such as the Tohono O'ohdam, Yaqui, Hopi, and Apache peoples.

The garden was built in conjunction with the National Park Foundation's First Bloom program. First Bloom is an effort that "reaches out to urban youth in their communities to teach them the science of native plants, encouraging them to protect the environment in America's celebrated national parks and in their own backyards," according to the park foundation.

Rangers from Tucson's Saguaro National Park worked with staff and students at Manzo to design and install the vegetable garden. The garden contains vegetables grown by native peoples of the region hundreds of years ago. These heirloom crops include tepary beans, de arbol chiles, Dia de San Juan corn, Yoeme basil, and O'odham melon.

"Another ethnobotany project that runs parallel to our vegetable garden is our Kino Heritage Fruit Tree Orchard," Thompson says. "Kino Heritage Fruit Trees are trees propagated from the oldest living fruit trees in and around the missions of Father Eusebio Francisco Kino, thought to be introduced to this area in the 17th and early 18th centuries. These fruit trees became some of the most important items exchanged between Europeans and native peoples. Over generations, these fruit trees became integral to local cultures and continue to be used for food and medicine, and have been incorporated into art and religion."

As the gardens developed, students and staff began composting food waste from the cafeteria. Methods include vermicomposting (which relies on worms to help break down the compost) and hot box composting. In hot box composting, heat is generated by the decaying food scraps, which increases the activity of microbes working to decompose the food while keeping pathogens and insect larvae in check. This results in quality batches of compost that can be used in the gardens.

Students collect and turn compost daily. According to Thompson, two things became clear very quickly: "Number one, it's tough to keep enough dry material on hand to keep up with the food waste, and number two, the majority of food waste from the cafeteria is not compostable.

"Thus the vision for building a chicken coop was born," says Thompson.

Chicken Coop as a Learning Tool

"Bedding from the chicken coop, filled with nitrogen-rich poop, can provide additional dry material [for the compost], and the chickens can make use of a lot of the food waste which is not compostable," Thompson says. "And in return, we get local eggs!"

The coop hosts six chickens, which the students look after daily. Chickens are given only organic feed, and they are free to range on the grass and compost piles for about six hours a day. The chicken coop has a cistern for collecting and storing rainwater, which supports the coop's water needs—an important element in a dry desert ecosystem. The coop also has a digital weather station, which measures wind speed and direction, temperature, humidity, dew point, and barometric pressure. The weather station helps students make the connection between climate and food production.

"Our vision for our vegetable garden as well as the chicken coop is not to expand here on campus, but rather to expand into students' backyards," Thompson says. "Barrio Hollywood has a large immigrant population not far removed from backyard agriculture, so it seems like a good fit."