Don’t be surprised that you didn’t know Kansas City owns a farm — and a cutting-edge farm at that.

Danny Rotert, a longtime political insider to Kansas City government, had never heard of it until a couple of months ago.

“I didn’t know it existed,” said Rotert, spokesman for Mayor Sly James. “I just had no idea.”

Yet the farm puts Kansas City in the forefront of other large cities nationwide.

And it’s all because of sewer sludge.

Every city produces tons of it, and every city tries to figure out what to do with it.

Kansas City’s solution: Use it as fertilizer on 1,340 acres it owns along the Missouri River next to the Birmingham wastewater treatment plant.

Corn and soybeans are the main crops, and when harvested they are sold to the expanding fuel-production industry to make biofuel — the crops are not intended for human consumption.

The ingenious part of the equation is that Kansas City has made $2.1 million in net income over the past six years doing something that used to cost it money.

“That is fantastic,” said Tammy Zborel, who works with a sustainability program for the National League of Cities. “That is not a common practice for cities to engage in that level of farming.”

The city used to burn all its waste in incinerators.

“That is an expensive process that takes a lot of water, takes a lot of gas, takes a lot of electricity, and it leaves us with a fairly inert ash,” said Kurt Bordewick, manager of the Water Services’ wastewater treatment division.

Applying sludge to land as fertilizer was another way to get rid of it, but finding enough land or even farmers who would use it was often difficult.

To dispose of the waste from the Birmingham plant, the city in the mid-1970s bought 300 acres on Missouri River bottomland and dug two lagoons to store the waste. Every two years the lagoons would be cleaned out, and some of the waste would be applied to the ground.

In the 1980s, the city purchased digesters that would remove the water from the waste, creating “biosolids,” or what became the city’s wonder fertilizer.

A few years later, the city purchased 600 more acres from farmers and put in another lagoon.

By then tenant farmers were growing crops for the city and using the city’s fertilizer. An elaborate system of pipes had been built underground to distribute the fertilizer to the land. Officials soon figured they needed more land.

The city was producing more biosolids than the farm could handle, Bordewick said. “So we kept buying up ground because we knew the city is getting bigger, and we knew there was going to be more people,” he said.

Department officials also knew the land probably would never be developed because of flooding issues.

Up until 2006, tenant farmers grew the crops, but production was a far cry from what Timothy Walters, farm manager for the water department, strongly believed it could be.

Walters, an agronomist, said the contract farmers had their own grounds and schedules to follow, making the city’s farm second fiddle. But the city’s biosolids need to be a top priority — they need to be used when they are ready. A freeze makes them even more difficult to use.

In addition, the seeds did not always have the best yield, and the rotation of crops could have been better, he thought.

“I needed more control over what was getting planted and how,” Walters said. “We have a very narrow window in the fall and a very narrow window in the spring.”

Walters took over the operation of the farm in 2006, and now the city does the bulk of the farming.

“We do all the tillage, and we plant the crops,” Walters said. “We don’t do the harvest because we can’t afford a $300,000 combine.”

For safety purposes, the water department conducts extensive testing and monitoring to make sure the biosolids applied to the land do not contain harmful contaminants. The property is gated and fenced.

The success is in the dollars.

From 2000 to 2005, under tenant farming, average yearly gross was $52,373. From 2006 to 2011, under city farming, average yearly gross was $455,451.

In addition, as more of the human waste is converted into Kansas City’s fertilizer, less is incinerated. The year 2007 was the last one when more biosolids were incinerated at the Birmingham plant than were used as fertilizer. Last year, 9,982 tons of fertilizer were spread on the farm, and only 2,044 tons were incinerated.

“It’s my goal to get out of the incinerator business,” Bordewick said.

Not that the farming enterprise has been problem-free.

City workers also planted more than 100,000 trees brought in from across Missouri. They hoped the grown trees would adorn the city’s parkways and boulevards.

But no one pruned the trees, and when the park department came to assess them, they weren’t up to standards.

It turns out the water department didn’t know much about growing trees. “We just stuck them in the ground,” Bordewick said.

Still, even those trees became useful as a shelterbelt against the wind. The trees also are being used to test how much fertilizer they absorb over time.

Aside from the savings, the farm also makes the city greener — fertilizer is more environmentally friendly than incineration, Bordewick said.

“We were doing this before green solutions and sustainability were everyday words and concepts,” he said.

Still, it’s the savings that make city officials happy.

“The big deal is the money,” Rotert said. “That is a revenue generator, by golly. … We need more of them.”

To reach Karen Dillon, call 816-234-4430, or send email to kdillon@kcstar.com.