Using sensors to spoon-feed crops with extreme precision

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JUDY WOODRUFF: Now: a look at trying to clean up the water supply in the country’s heartland.

For decades, American farmers have been applying nitrogen fertilizer, in some cases too generously, to crops. Much of that fertilizer has found its way into runoff, contaminating water supplies and forcing many communities to invest heavily in water treatment plants.

From NET in Nebraska, Ariana Brochas of Harvest Public Media reports on new technologies farmers are using to reduce contamination from their fields.

It’s part of our series about the Leading Edge of science and tech.

ARIANA BROCHAS: When University of Nebraska professor Richard Ferguson looks at a cornfield, he has no illusions.

RICHARD FERGUSON, University of Nebraska – Lincoln: To profitably produce corn in Nebraska, we have to apply nitrogen fertilizer. In many cases, in the past, we applied more than we really needed.

ARIANA BROCHAS: Ferguson wants to reduce the chance that excess nitrogen will get into the groundwater. His high-tech approach, called Project SENSE, uses sensor technology to help farmers fertilize during the growing season as timely and precisely as possible.

RICHARD FERGUSON: If we can make them more money by the use of sensor technology, we think that’s something they would adopt.

ARIANA BROCHAS: Project SENSE is being put to the test in areas where groundwater nitrate levels are high. Today, it’s at the Seim family farm in Central Nebraska.

The machine’s arms have sensors that gauge how much nitrogen the plants need. A computer fires applicators to deliver fertilizer, practically feeding plants one by one.

For Anthony Seim, SENSE is another tool for his family to try.

ANTHONY SEIM, Seim Ag Technology: I don’t think there’s any farmer that wakes up in the morning and says, I’m just going to go dump 1,000 gallons of fertilizer down a ditch. Everybody’s trying. It’s just that it doesn’t always work. There’s a lot of things that we can’t control, weather being the biggest one.

ARIANA BROCHAS: Anthony and his brothers have adopted their father’s ideology of progressive farming. Like many farmers, Ken Seim used to put nearly all his fertilizer on the ground before the crops were even planted.

KEN SEIM, Owner, Seim Ag Technology: Today, we apply everything in we call it spoon-feeding, which is a term for just a little bit at a time.

ARIANA BROCHAS: Noah Seim shows off one method of spoon-feeding.

It’s called chemigation or fertigation. It uses a center pivot hooked up to a fertilizer tank. This lets the Seims control how much nitrogen gets applied each time they water. It’s less precise, but less expensive than Project SENSE, but still allows farmers to vary fertilizer rates in response to weather, soil moisture and plant growth.

Across the Missouri River in Iowa, you won’t find many center pivots. Here, they rely on good soil and rain.

DICK SLOAN, Iowa Corn and Soy Farmer: We got a three-inch rain 24 hours or 48 hours ago, but you can see how the water didn’t come down and leave a channel through my field. A lot of soy conversation is about slowing water down.

ARIANA BROCHAS: Dick Sloan farms in Eastern Iowa, near Cedar Rapids.

Here, systems of underground pipe, or tiles, drain excess water off fields. But those tiles also carry fertilizer and pesticides and drain directly into nearby streams and rivers. This kind of field runoff isn’t regulated, and Iowa has some of the worst water pollution in the Midwest.

Sloan uses no-till and cover crops to help slow and filter water before it gets to his tiles.

DICK SLOAN: You can see how everything’s kind of knitted together.

ARIANA BROCHAS: He also devotes some of his land to prairie strips, land that could be used to grow corn or soybeans.

DICK SLOAN: As water moves down across the field, it encounters this contoured strip that will stop any residue from getting through there and have less water getting polluted as it goes down to the Cedar River then on down to the Mississippi and down to the Gulf. So that’s the hope.

ARIANA BROCHAS: Former Iowa extension agent Chad Ingels has worked with farmers like Dick Sloan on field practices to improve water quality in Northeast Iowa. One new tool is something you can’t see. It’s called a bioreactor.

CHAD INGELS, Iowa State University Extension and Outreach: The water from this field would normally dump right out into this ditch behind us. But we have it go through this structure. And there’s a set of gates on the inside that diverts it in the bioreactor that is underneath this grassy area. And the bioreactor is just a trench that is 100-feet-long and 30-feet-wide and it is filled with wood chips.

ARIANA BROCHAS: As the nitrate-laden water passes through the wood chips, microbes turn the nitrates into harmless nitrogen gas, which makes up most of our atmosphere.

CHAD INGELS: I think almost every field needs some kind of practice, whether it’s a bioreactor, no-till, just better nitrogen and phosphorus management.

ARIANA BROCHAS: Craig Cox with the Environmental Working Group in Ames, Iowa, agrees that every field needs some sort of management. But he says voluntary measures don’t work.

CRAIG COX: Otherwise, the water would be in a lot better shape than it is.

ARIANA BROCHAS: In the last decade, the federal government has spent more than $3 billion to support measures that reduce water pollution from Iowa farms. The Environmental Working Group monitored the use of two conservation practices over a five-year period and found the net gain was negligible.

CRAIG COX: Here’s the good news story. We got a new buffer. But here’s the bad news story, right? We had a buffer, and now we don’t have one anymore.

ARIANA BROCHAS: Cox says some standard conservation practices should be required of all farmers, but Dick Sloan says his field practices can’t be mandated on his neighbors.

DICK SLOAN: People have a natural negative reaction to regulation. Anybody would. It’s not just — farmers are just so much like everybody else. It’s going to take time for them to question what they’re doing.

KEN SEIM: Farmers are very independent, but the reality is, if we won’t be stewards ourselves, someone will have to help us be a steward.

CRAIG COX: This is a solvable problem. It’s just everyone has to do their part.

KEN SEIM: One thing I always tell people when I work with them, if you can make me better at what I’m doing, I’m in.

ARIANA BROCHAS: For the “PBS NewsHour,” I’m Ariana Brochas in Lincoln, Nebraska.

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