Spring planting season is starting across the northern hemisphere. But before seeds go into the ground, nutrients go into the soil. Typically nitrogen fertilizer.

“Right now, we’re kind of … we’ll be in the thick of it,” farmer Matt Ubel said from the cab of his huge green fertilizer spreader near Wheaton, Kansas. “Lot of nitrogen gets put on in the spring.”

The high cost of fertilizer and other farming necessities pushed many row crop farmers into the red last year. Ubel says some were holding out for lower prices this spring, only to see the price of the most common nitrogen fertilizer, urea, spike close to 30% when Iran shut down shipping in the Strait of Hormuz, halting close to half the world’s fertilizer trade.

“This probably threw some guys for a loop,” said Ubel.

The Persian Gulf, nitrogen fertilizer hub of the world

Farmers in rural Kansas, and across the world, are feeling the unexpected consequences of the war in the Persian Gulf because closing the Strait of Hormuz has bottled up almost 50% of the world’s urea exports.

Every plant needs nitrogen to grow. The best source of nitrogen is natural gas, and the Gulf states are sitting on the world’s largest gas reserve.

“If you had sat us down before and said, ‘Hey, I want you to think of the nightmare scenario for fertilizer. What would it be?’ It would be this exact event during this exact time of year,” said Josh Linville, who oversees the global fertilizer department at the brokerage firm StoneX.

Linville says urea that had been expected to arrive in the United States next month, in the peak of planting season, won’t come.

The Fertilizer Institute predicts that U.S. farmers will be short some 2,000,000 tons of urea this spring.

The United States is currently the world’s top natural gas producer, which supports a robust domestic fertilizer industry. Still, U.S. companies import about 18% of the nitrogen fertilizer sold in this country, drawing heavily on imports to cover the spring planting surge.

Other countries are much more dependent on petrochemical imports. Liquefied Natural Gas imports from the Persian Gulf fuel urea production in some of the top-producing countries. Or it did.

“Countries like India, the second biggest urea producer in the world, their production rates are starting to fall. Pakistan, China, all of these major producing countries are struggling to get these gas supplies,” says Linville. “And all of a sudden, they’re having to say, well, we’ve only got so much. We need to lower our fertilizer production to put into some of these other industries.”

And natural gas isn’t the only problem. About half the world’s sulfur exports were shipped out of the Strait of Hormuz.

For instance, sulfur is an important plant nutrient on its own, but it’s also a critical ingredient in phosphate fertilizer.

“We do produce a lot of phosphate fertilizers here in the U.S., but if we can’t get sulfur, we can’t produce phosphate fertilizers,” said Veronica Nigh, chief economist at the Fertilizer Institute. “And so, it’s kind of a twofer there.”

No easy answers

Federal lawmakers are trying to help.. Bipartisan Senate legislation aims to lower fertilizer costs by requiring more transparent pricing.

The Trump Administration is lifting barriers to fertilizer imports from Venezuela and Morocco.

“They’re trying to pull a number of levers,” said Nigh. “I think that it’s the acknowledgement that there aren’t a lot of easy answers to this problem.”

There’s very little slack in the fertilizer supply chain. The product doesn’t store well, some of it is prone to blowing up, some if it gets clumpy and hard to use with the slightest moisture. According to Nigh, fertilizer plants tend to operate at capacity and take years to construct. Iran was a top urea producer and exporter before the war. It’s unclear when or if that capacity will come back online.

The gas fields in Iran and Qatar are the world’s largest natural gas reserves. They supplied fertilizer production in India, normally the world’s second-largest nitrogen fertilizer producer. But, those fields have been severely damaged in the war.

Even after the Strait of Hormuz reopens, it will likely take months to straighten out the fertilizer supply chain.

“How long does it take until we get back to normal? It could be a while,” Nigh said.

Meantime, American farmers may have to make hard choices at planting time. Corn, for instance, needs a lot of nitrogen to thrive. Soybeans need less, so U.S. farmers may grow less corn and more soybeans. Farmers who can’t source fertilizer may even skip a year.

“Think watermelons and cantaloupe and things along those lines in Texas, those don’t get planted,” said Nigh, “Or pumpkins in Indiana.”

On the one hand, less fertilizer use could be good for the environment. Fertilizer runoff pollutes water sources and fuels toxic algae blooms.

But the fertilizer shock triggered by the attack on Iran will invariably mean that people around the world have less to eat. And that could be an acute problem in vulnerable countries, especially those dependent on Persian Gulf oil for fertilizer.

“What our product is used for, is food, is the production of food,” Nigh said. “So the consequences aren’t going to be immediate, but they could be substantial.

On Tuesday, the National Transportation Safety Board provided new details of the final minutes before an Air Canada jet collided with a fire truck at LaGuardia Airport in New York.

The timeline from federal investigators and air traffic audio reviewed by The New York Times both suggest that the controllers may have been distracted before the crash, which killed the plane’s two pilots and left dozens injured late Sunday.

Here are critical moments leading up to the deadliest collision at the airport in more than three decades:

Air traffic controllers were responding to an emergency with United Airlines Flight 2384 several minutes before the crash, posing a possible distraction to air traffic controllers.

After being on the tarmac for over two hours, the United flight, bound for Chicago, had aborted its first takeoff attempt at 10:40 p.m. Passengers were told the plane had “a transient issue,” according to a passenger who requested anonymity in order to protect her privacy.

The pilots made a second attempt at takeoff about 40 minutes later and aborted again.

At 11:31 p.m., United flight had declared an emergency and requested a gate assignment, according to air traffic control audio reviewed by The Times. An odor on the plane had sickened members of the flight crew.

Four minutes later, the plane was assigned a gate and told to wait for emergency responders.

Air Canada Express Flight 8486 was set to land at LaGuardia Airport when the approach controller, who manages flights as they near the airport, ordered the airplane to contact the control tower, National Transportation Safety Board officials said on Tuesday.

The flight crew began lowering the landing gear. The plane was cleared to land on Runway 4 and advised that it was No. 2 for landing, said Doug Brazy, a senior aviation accident investigator with the National Transportation Safety Board.

One minute and 26 seconds before the crash, an electronic callout indicated that the plane was 1,000 feet from the ground.

A passenger told The Times that a flight attendant warned the passengers to leave any luggage behind if the plane made an emergency landing. It’s unclear why this warning was made.

Around 11:37 p.m., or 25 seconds before the crash, “Truck 1” made a request to cross Runway 4 at Taxiway D, the same runway that the Air Canada jet was set to land on. The request was made to respond to the emergency with the United Airlines plane.

Five seconds later, the truck, which later crashed with the jet, was cleared to enter the runway, officials said. An air traffic controller quickly responded: “Truck 1 and company, cross 4 at Delta.”

The officers aboard “Truck 1” read back the runway clearance. That’s a mandatory practice to ensure that the message was received correctly, and to verify that both the air traffic controllers and the recipient of the information understood the instructions.

Five seconds later, the plane was 30 feet above the ground, and the tower instructed a Frontier Airlines aircraft to hold its position.

LaGuardia Airport has a “Runway Status Lights” system that includes red runway entrance lights at taxiway and runway crossings. The lights, which are set in the pavement, activate automatically when high-speed traffic is on the runway or approaching it.

While there is speculation about whether the fire truck ran a red runway status light, a Times analysis of the crash footage suggests the lights on Runway 4 appeared to be functioning properly when the fire truck entered the runway.

By design, the lights can go dark a couple of seconds before a landing or taking-off plane passes the intersection. The truck may have entered the runway in that brief window. What remains unknown is whether the crew members heard the controller’s instruction to stop, and, if so, why they proceeded regardless. The lights do not replace clearances given by the air traffic controllers.

Nine seconds before the collision, an air traffic controller instructed “Truck 1” to stop. There were other vehicles behind the fire truck that did not proceed to the runway.

“Stop, stop, stop, stop, Truck 1, stop, stop, stop,” the controller said. Sounds consistent with the plane’s landing gear slamming against the pavement could be heard in the audio from the cockpit voice recorder.

Four seconds before the regional jet plowed into the fire truck, the controller again said, “Stop, Truck 1, stop!”

Investigators have not determined whether the operators of the fire truck heard orders to stop before colliding with the Air Canada flight.