The yellow bus chugged up and up the grade, into the back of the lush Wai­ma­nalo valley — past the ref­use station, homes under construction, crowded family plots, nurseries and other agricultural lots, drawing close to the steep Koo­lau peaks topped with cottony clouds.

Nearly at the back of the valley, it reached its destination: Kanu Farms, where leaseholders Shellee and Gabe Machado stood waiting to greet a tour group from the Hawaii Conservation Conference.

The July 19 one-time tour was titled "What Does a Sustainable Farm Look (and Taste!) Like?" Its intent was to give a close-up look at how farmers create a "sustainable" farm from scratch.

"It’s not easy, that’s all I’ve got to say," said Gabe Machado. He wasn’t joking.

Dedication, training and commitment are required to build a sustainable operation, along with a major investment of time and money, and plenty of patience.

"Agriculture is not just about the land; it’s about the people and the economy," said Kim Coffee-Isaak, executive director of the Agricultural Leadership Foundation of Hawaii, who helped coordinate the tour.

At Kanu Farms the Machados grow figs and breadfruit, citrus, lychee, mango, banana and avocado, and cultivate tila­pia.

There are also small vegetable and herb gardens, planted with test varieties of pickling cucumbers, yellow beans, beets and other warm-weather vegetables.

But just because you’re hungry doesn’t mean the food is on the table. Tour group members didn’t "taste" Kanu Farms’ harvest because most products weren’t ripe for picking that day. A few visitors passed around one lightly sweet fig; in the next week or two, the Machados said, there would be a harvest.

Lunch at Sweet Home Wai­­m­a­nalo came next. At the cafe, owner Joanne Kapo­lolu had transformed the menu to emphasize healthful and local ingredients.

She served up Wai­ma­nalo-grown greens in a salad with house-made dressing and a fresh, delicious bok choy slaw, along with a choice of wraps stuffed with imported mainland chicken or tofu, or kalua pork sandwiches with a spicy homemade sauce.

The tour was expected to view a rooftop garden at the restaurant. Instead, Kapo­lolu explained that while a garden had been installed, and even featured in a local film, "Ingredients," about Hawaii’s sustainable food movement, the expense of adding a needed staircase made the operation too expensive to continue.

FarmRoof is concentrating on large-scale hydroponic projects now, Kapo­lolu said, including one on the roof of Castle Medical Center, where greens for the cafeteria’s meals are grown.

Kapololu, a breast cancer survivor who’s a strong advocate for natural food, told the tour group that going "local" and "sustainable" were her goals, but making changes came at a cost. Even switching over to compostable paper goods was far more expensive than using styrofoam, she noted.

Kapololu did not pay herself for the first two years. But after word got around about the quality of the food — and Sweet Home Wai­ma­nalo was featured on "Diners, Drive-ins and Dives" — business skyrocketed.

"We wanted to slowly wean people into paying more for their good food," Kapo­lolu explained.

The cafe is now busy enough that it closes on Tuesdays so the staff can prep for the week to come.

And in the coming months, community members plan to open a co-op market next door, in the former Mel’s Market location, buying and selling only local fresh fruits and vegetables.

Back at Kanu Farms, the mood was upbeat, but the experience was not all about bounty and sunny reports.

The farm was immaculate. The Machados, modest and good-humored, were smiling but looked a little tired. After a few minutes of questions and answers, Shellee Machado admitted that the family was still "a long ways away" from putting the operation in the black.

The farm is a work in progress; a five-year development plan is about halfway complete.

The seven acres that the Machados lease on state agricultural land had been operated as a nursery and subjected to much traffic by heavy equipment, packing the earth down "hard as a parking lot," Gabe Machado said. It had also been regularly and heavily sprayed with pesticides.

The Machados would have to rehabilitate the soil before they could even say they were starting from "scratch."

Working with Jean Brokish, director of the nonprofit Oahu Resource Conservation & Development Council, the Machados committed to work the compacted soil, limit use of chemicals and even plant grass along their roadside to reduce erosion and runoff.

Ultimately, having a productive agricultural operation that is recognized as sustainable can allow Kanu Farm to sell "value-added" specialty products from the farm, balancing out the bottom line, the Machados said.

There are future plans for beehives, apples, plums and peaches.

"We’re realizing we can grow a lot of things we didn’t think we could," Machado said.

To grow plants safely with organic fertilizer, Kanu Farm has been experimenting with composting worms and raising tila­pia for aquaponics.

Tour members followed along intently, peering into open sheds the Machados built to shelter loose soil from Wai­ma­nalo’s frequent rain, and taking notes as Shellee Machado explained that tila­pia grow to maturity in 12 to 18 months.

"It’s sort of like a science project, but nobody’s holding our hand," she said.