MAWAMBALA, Tanzania — A world away from the questions about pay to play, the links to foreign governments and talk that the Clinton Foundation is, as Donald Trump puts it, a "vast criminal enterprise," Jackson Kipati walks down a path to a field of dark dirt where he has just planted brown beans.

In the next field, a woman hoists a large hoe over her head, driving it into the ground over and over. The bright sun hits a nearby collection of low brick homes and the small village office built of mud stucco walls and capped with a metal roof.

Here, the calculus of what the Clinton Foundation is, and means, is measured in sacks of maize and rows of crops.

Because of the foundation's intervention, the 62-year-old Kipati upped his maize harvest from seven sacks to 20. And Kipati didn't just boost his harvest, he got a better price at market. The extra money helped send his children to better schools, put a new roof on his house and plant a row of pine trees to sell as lumber a decade from now.

But the foundation that bears the name of Hillary and Bill Clinton is also facing serious questions about its donors and how they intersect with Hillary Clinton's public work.

Editorial writers at the Boston Globe have said the foundation should stop accepting money, while the Associated Press uncovered instances in which foundation donors got meetings with Clinton while she served as the nation's top diplomat.

The ethical and political booby traps the foundation creates for Hillary Clinton center on where the money comes from. But concerns over the source of funds exist side-by-side with the real gains the foundation delivers around the world.

The farming project in rural Tanzania is a window into the signature Clinton Foundation style that attracts millions of dollars in support on one end and creates market-driven opportunity on the other. To understand the foundation requires looking at both.

Road to market

On a dusty road in the middle of Tanzania, more than 300 miles west of the Indian Ocean, two young men on bicycles have stopped. They are muscling and rearranging three 50-kilogram (110-pound) sacks of maize draped across the back of one of the bikes. The other bike teeters under a similar load.

About a five-hour walk away is the local grain trader. When the two parties meet, the grain trader has the upper hand. Everyone is selling now, and he knows these guys won't be hauling the heavy crop back home if the price isn't right.

These are the sort of people the Clinton Foundation's farming project in Tanzania aims to help. "We want to see them grow more on the same land, and for a better price," said Seleman Kaoneka, the program manager.

Boosting yields is simple enough, and with the right techniques, almost predictable. In fact, it has been achieved in a handful of African nations over the years. What has proved trickier is making it stick and making it pay for the farmers. The foundation, through its Clinton Development Initiative, thinks it has a lasting solution grounded firmly in sound business practices.

Leading by example

On the road to Mawambala, the Clinton Development Initiative planted one of over 60 demonstration plots it has dotted across the region.

"We always put them where people will see them as they go by," Jafary Kisumbe, the project's lead field officer, said.

Kisumbe and the other field officers use these plots to show local farmers how to prepare the soil, plant more robust seed and use fertilizer at the right time.

The project has 12 methods it teaches farmers. Not a single one is new. Kipati himself said he had heard about most of these methods before.

"The government sent teachers," he said. "But it was just talk. This time, I see how it is done, and I see how the fields grow more. When they say plant every 30 centimeters (about one foot), I can see how that looks."

The project leaves little to chance. The local field officers go by motorcycle from village to village. They recruit and teach new farmers and form them into clubs and gradually build out further and further. They use smartphones and tablets to track the use of what they've taught, geocoded down to the exact fields.

Back at the foundation headquarters in New York, Clinton Development Initiative staff monitor it all, including the size of the harvest and the prices received. The Clinton Foundation prides itself on this fusion of data systems worthy of the University of Pennsylvania's Wharton School and back-country rural community organizing.

But teaching and tracking progress are not enough.

Every agricultural expert the Tampa Bay Times spoke to said if you want a lasting change in farming in sub-Saharan Africa, you have to tie it to an actual business plan.

Ephraim Nkonya, a Tanzanian research fellow at the International Food Policy Research Institute, said past efforts typically treated locals as subsistence farmers who grew food only to feed their families, rather than people who might want to make a profit from farming.

Nkoya said that limited view helps explain the "low adoption of technologies even when farmers see that such technology is better than their traditional technology."

The new ways don't come without risk, however. Farmers need to spend more money up front. A key job for the field officers is to persuade them that it will pay.

Meet in Mawambala

Over 30 people, nearly half of them women, have packed themselves into the dark village office in Mawambala, They sit on narrow wooden benches. The village chairman and the village chief executive sit at a wooden table at the front. One woman in the back peppers the project staff with questions in Swahili.

A central piece of the farming operation involves storing everyone's harvest of maize, soybeans or sunflower seeds in centralized warehouses.

"How do I know my maize will be counted correctly?" she asks.

Kisumbe explains that everything is weighed and recorded. The simple use of scales remains a bit of a novelty. The typical approach is to fill a sack and call it 50 kilograms, although it might hold more or less.

After the meeting, Rhoda Kagine says she's nervous about spending more money to do what the project requires.

"Yes, I'm very worried," Kagine said. "I'm worried to borrow. What if there's no rain? What about disease? But I'm going to do it. Because I see that these fields grow more."

The numbers can be a hurdle. A local farmer said his upfront costs were 50 percent higher, but the yield was triple. Farmers have different ways to come up with the cash. If they borrow, as many do, the project staff have charted the interest rates that remain safe, even in the face of drought or other setbacks. But there are no perfect guarantees.

A big development

To break the cycle of subsistence farming, the foundation yokes the big to the small.

At the center of the village outreach effort sits a commercial farm of over 2,000 acres, an unusually large parcel for Tanzania. The Clinton Development Initiative leased the land for 20 years from the Tanzanian government and set up a for-profit company to run it.

It is a $5 million high-end operation. Where the local farmers rent a bull to plow, this farm has two big shiny green tractors and a fire engine red combine that stands 13 feet tall. They hired a 26-year-old New Zealander to oversee the activities. Right now, the farm produces maize, soybeans and sunflowers.

The core idea is to interweave the business of the commercial farm with that of the small farmers. The big farm buys seeds and fertilizer at bulk rates and passes the savings on to the farmers. When the time comes to sell, they combine their harvests.

"We look for contracts with big buyers," said Simon Hart, country director in Tanzania for the Clinton Development Initiative. "We grow what the farmers grow, and between our output and theirs, we fulfill our end of the deal."

The commercial farm stores part of everyone's harvest until the market is up. No more bags on the backs of bikes and no more middlemen.

In theory, the small farmers will make more each year and profits from the commercial farm will feed the network of field officers and the expanding outreach to more villages.

Walker Morris, chief executive officer of the Clinton Development Initiative, said that at some point all of this reverts back to Tanzanian ownership. Morris admits that he's not sure how that will look, but he's clear about the end goal.

"We're looking to make this sustainable after we leave," Morris said during a telephone interview from New York. "We have a fairly long time horizon, but we don't want to be here forever."

The foundation says that in neighboring Malawi, where it piloted this approach eight years ago, the average farming household has more than doubled its income. Morris said over 100,000 farmers have signed on, and if the Clinton Development Initiative hadn't expanded from one to three commercial farms, the company there would be profitable.

Uncertain future

Before 2008, the foundation was simply the impressive result of a former president who parlayed his personal relationships into multimillion-dollar donations. Bill Clinton's star appeal drew support from foreign governments, major corporations and the mega-rich around the globe. Its activities raised no particular ethical issues.

But after 2008, when President-elect Barack Obama nominated Hillary Clinton to be secretary of state, it triggered a whole set of concerns over the foreign governments, especially the Arab Gulf States, that had given millions to the foundation.

The Senate signed off on Clinton's nomination when the foundation agreed to list its donors and Clinton promised to steer clear of any business where the activities of the government and foundation directly overlapped.

The arrangement hasn't satisfied everyone, and the Clinton Foundation hasn't always lived up to its terms, failing at times to disclose all of its donors. Concerns will only grow if Clinton is elected president, said John Wonderlich, executive director of the government transparency group the Sunlight Foundation.

"The foundation can't exist without presenting ethical headaches and potential conflicts of interest," Wonderlich said.

Questions reached a tipping point when emails from Clinton's time at the State Department emerged showing people with foundation ties asking Huma Abedin, one of Hillary Clinton's top aides, to field requests from foundation donors.

After a flurry of news reports, Bill Clinton announced key changes. He said that if his wife won the presidency, he would step down from the board and raise no more money on its behalf. The foundation would stop taking any foreign funds, along with donations from any corporation, foreign or domestic.

Those funding rules leave no room for the Clinton Development Initiative.

Foreign funders

The money and donors behind the Tanzania farming project come with no discernible ethical taint, but they are largely foreign and will be off-limits should Hillary Clinton win. The primary funders are the Dutch government, two Dutch and United Kingdom lottery funds, and the British-based Hunter Foundation. The Bill and Melinda Gates Foundation (a group that has given funding to PolitiFact to fact-check global health and development) also participates through its Alliance for a Green Revolution in Africa project.

To cope, the Clinton Development Initiative plans to leave the Clinton Foundation and set up shop inside a different organization.

"We are looking for different landing places for CDI," said Morris. "We hope to find an organization that presents the best opportunity for us to continue what we're doing in its entirety."

Morris said there are a number of outfits that share his program's focus on merging a sustainable profit-driven commercial farm with the interests of small farmers. More than that he won't disclose, but he says he's optimistic the project will find a new home.

The shift could be good for the foundation, and for the Clintons.

"If the president can't anger a foreign leader because children (helped by a foundation project) might be harmed, that's a conflict that shouldn't be," Wonderlich said.

Ann Skeet, who focuses on nonprofit governance at Santa Clara University, agreed that an amicable split between the Clintons and the foundation's work would put the foundation itself on more sound footing.

"The foundation needs to get on with its business and not be distracted by a political situation," Skeet said. "Board members have a duty of care and a duty of loyalty to serving the public interest of the nonprofit. They should not have divided loyalties."

Jon Greenberg traveled to Africa in August as part of PolitiFact's Global News Service to report on stories about global health and development. Contact him at jgreenberg@tampabay.com. Follow @JonZGreenberg.