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Crop Sensors

When drought destroyed the Oklahoma corn crop two years in a row, farmers were optimistic that the winter wheat that followed would be the bright spot. Yet, what was lurking in the soil tipped the scale in the wrong direction.

“Normal corn yields here are 100 to 120 bushels per acre. In a really good year, we’ll see 150,” says Brent Rendel, who farms in Miami, Oklahoma. “During the drought, most yields were in the 20- to 40-bushel-per-acre range. Many planted their wheat into that and did not account for the residual nitrogen left over from the failed corn crop.”

As a result, large portions of wheat fields fell flat.

“Because of nitrogen carryover and mineralization, farmers who continued to apply the standard amount of fertilizer found much of their wheat fields lodging because of over-
application, which resulted in lower yields, lower quality wheat, 60% slower harvest speeds, and more wear and tear on the combine,” says Neil Martin, a solutions specialist with Record Harvest.

Concerned the cycle would repeat itself, farmers turned to technology for a solution. 

“It was the perfect storm in that they had seen the disaster the year before and were attempting to avoid that same issue,” notes Martin. “Crop sensors were an option to better assess how much nitrogen was out there.” 

Popularity of the technology began exploding in September 2012. Within a nine-month period, Martin sold eight complete Trimble GreenSeeker systems (which cost between $16,000 and $20,000 each) and 25 handheld versions that have a price tag of about $500.

Strong proponent
As one of the initial testers (and eventually an owner of a full GreenSeeker system and a handheld device), Rendel has been using the technology since its inception more than a decade ago. 

“Brent has played a huge part in the validation of the technology,” says Brian Arnall, Oklahoma State University precision nutrient management Extension specialist. “He helped us learn so much about the technology and how to adapt it.”

Yet, Rendel admits he was initially skeptical. 

“The very first time I used crop sensors on a 110-acre field, it called for zero nitrogen,” he recalls. 

Rendel was being told his ground needed no nitrogen, and the recommendation was coming from an Extension agent who had just learned the system. 

“I asked him to redo the reading a couple of weeks later because I didn’t believe the results,” he recalls.

“Crop sensors go against everything you’ve been taught about applying nitrogen,” notes Arnall. “You know the plant needs nitrogen and that it’s the most limiting factor. Now you’re being told that it needs nothing. That can’t be because you always fertilize.”

When the second reading came back as zero again, Rendel let it go. “It was just one field,” he notes. “What’s the worst that could happen.”

While his crop turned out fine, that willingness to take a risk allowed him to learn from the latest technology.

“I never know who from Oklahoma State is going up to Brent’s place to try something new,” notes Arnall. “He is always looking for that next thing to push production and efficiencies.”

Through the years, the system has continued to balance nitrogen levels while reducing his input costs, especially during the recent drought. “I still put down 25 pounds of planting nitrogen. If I didn’t use the sensors, I would normally top-dress 70 to 100 pounds of nitrogen,” he says. “In 2012, the GreenSeeker backed it off to where most of my fields were getting about 25 pounds of top-dress nitrogen. Some areas would get as high as 50, which is still less than the full rate. There were actually a couple of fields that didn’t get any at all. I also had significantly less lodging on my wheat than what others in my area saw.”

As an advocate for the technology, crop sensors are more than a tool to determine nitrogen levels for Rendel. 

“Since I started using the sensors, it’s helped me understand why my wheat didn’t fall down and my neighbor’s did,” he says. “I understand why I’ve got one field with a really brilliant nitrogen strip, but another field with the same variety planted on the same day doesn’t show as strong a strip. The system has raised my knowledge level, because it shows me things I would have just chalked up to a field being good or bad.”

Changing a mind-set
When Rendel stands in front of farmers and tells his story of savings and little to no lodging, they’re still not convinced.

“As a farmer, I hate to not do something that I could have done to make myself grain and more money,” says Rendel. “If somebody is telling me to put on less fertilizer because I don’t need it, I’m thinking it’s only going to cost me an extra $5 per acre to add that extra nitrogen, which isn’t very much. It’s cheap insurance and it’s what everybody comes back to.”

It’s a frustration many in the industry struggle with.

“The hardest part is, nitrogen is one of those nutrients that a little more, typically, doesn’t hurt,” explains Arnall. “It’s a safe bet because you’d rather overapply 1 pound of nitrogen than lose a bushel of grain. There’s that fear that if you reduce what you’re doing, you will reduce your yield because, mentally, it’s been drilled into you for decades that nitrogen equals yield.”

While Rendel agrees the extra nitrogen does offer the security many bank on, you also have to look at the potential payback.

“The return on investment is basically a field or two. I’m not even talking years. I’m talking a couple of fields, and you pay for the system,” he says. “Yet technology like auto steer, which if you do a very careful analysis and a lot of spraying or spreading, may pay for itself over its lifetime. However, when I get in that seat and punch auto steer, my life just got better. I have instant gratification. The second I start using a crop sensor system, I have instant doubt. That’s the hurdle.”

Arnall takes a different strategy than Rendel when talking to farmers.

“I don’t focus on cutting nitrogen,” he explains. “I approach it from an efficiency standpoint and how to apply nitrogen only where it’s needed. In some areas, you may increase the rate; in other areas, you may decrease it.”

Last year, Arnall worked with a farmer to change the producer’s perception that he’s not taking away but, rather, he’s reallocating.

“He had 10 fields, and his normal top-dress would have been approximately 50 pounds of nitrogen,” Arnall says. 

No two fields were alike, and recommendations varied widely – from 0 on one field to 100 pounds on another. “When he was done fertilizing, based off the GreenSeeker, he applied about 52 pounds of nitrogen on average,” continues Arnall. “In the end, he still applied about the same amount of nitrogen, but the way he distributed it is what actually changed.”

Law of averages
How much nitrogen it takes to grow a crop is based on averages. Yet, research at Oklahoma State University revealed that if you base nitrogen application on averages, you are wrong more often than you are right.

“The thumb rule for wheat in my area, and it generally applies to the Winter Wheat Belt, is for every bushel of wheat I want to harvest, I need to put down 2 pounds of nitrogen,” says Rendel. 

In his part of the state, farmers try to target around 50 bushels per acre, which means most apply around 100 pounds of nitrogen. 

“However, that’s only correct one third of the time. One third of the time it’s not enough nitrogen, and the other third, it’s too much,” explains Rendel. “That means if you’re using the thumb rule to apply your nitrogen and not sensors, you are wrong twice as often as you are right. A third of the time you should have put on more nitrogen and made more money.”

If that’s not enough to convince you to reassess adopting the technology, the return on investment Oklahoma State University’s analysis revealed should.

“In Oklahoma winter wheat, over the last 10 years, it comes up to about $10 per acre in either savings or increased profit when using crop sensor technology,” says Arnall. “In corn, that number runs between $20 and $25 an acre, which includes a fair amount of research we did in Missouri.”

While some states, like Maryland, Oklahoma, and Missouri, have seen an increased interest in the technology due to programs like EQIP, there is still a lot of room for growth. “Oklahoma has approximately a half million acres of nitrogen-rich strips applied,” says Arnall. “Only 40% of those are actually sensed with a sensor of any kind.”

From the very beginning, Rendel has placed nitrogen-rich strips in his fields to provide a reference point on nitrogen needs. Others, however, aren’t convinced these are a viable option. “I haven’t quite understood the pushback,” says Arnall. “I think there’s a perception that it takes more time, but it’s not a massive undertaking. We had a producer take care of 2,500 acres in four hours.”

Arnall goes on to tell the story of a producer in southwest Oklahoma who actually did the calculations on the value of nitrogen-rich strips.

“He added up the time he spent applying his nitrogen-rich strips and sensing them and how much money he had saved over six years,” says Arnall. “It worked out to be about $8,000 an hour for the time spent applying and sensing.”

Tipping the scale
Experts in the industry are optimistic this technology will see widespread adoption over the next few years. 

“I do see that as more and more Oklahoma producers purchase their own sprayers – whether it’s pull-type or self-propelled – the adoption of crop sensor technology will increase significantly,” predicts Arnall. 

Generally, farmers tend to invest in technology when they have extra cash in their pockets. As commodity prices tumble, will it stall adoption? Arnall believes the opposite should occur.

“Producers invest more when commodity prices are higher. For me, the opportune time to invest, which is quite low compared to buying a new combine, would be when margins are narrower,” Arnall explains. 

“When crop prices are down and input prices are still high, you need to do everything you can to make sure your efficiencies are the best in those years. I’m curious to see what happens this year,” he says.

“I don’t know how you convince people,” says Rendel. “Do you put a dollar bill on their dashboard? Could you put a calculation up on the screen that would say you just saved this much money? It’s a hard nut to crack.”

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