Precision Farming Can Better Target Inputs for Higher Yields
A few years ago, Bob Braun reviewed a summertime satellite image of one of his fields with an agronomist.
“One part was all in red,” says the LeSueur, Minnesota, farmer. Initially, he thought this area needed a shot of side-dressed nitrogen (N). Braun, who had farmed the field for decades, though, looked a bit closer. He traveled to the spot to find sopping-wet soil.
“Actually, it needed more tile – not more nitrogen,” says Braun, who farms with his son Nate, brothers David and Brian, and Brian’s son-in-law Ryan Thelemann.
That story tells a lot about how to interpret data gleaned from precision farming maps. Aerial and satellite imagery maps can reveal much about a field’s history and how to best target inputs for reaping maximum economic yields. Still, they’re no substitute for knowing and walking your fields.
“No one else besides you can know what is going on in your fields,” says Braun. “It may be a soil issue; it may be a weed issue. In the end, you are the one who has to determine it.”
On the other hand, precision farming maps can reveal field secrets initially invisible to the naked eye. Braun once sidedressed late-season N on a field where a nitrogen advisory service indicated the sidedressing trip would pay.
“My brother was running a grain cart when I came in to combine,” he says. “He called on the radio and said, ‘This field will really be bad – the corn looks like just a stalk and an ear.’
“Well, we took 250-bushel-per-acre corn off that field,” he says. “The side-dressing application paid off. It all came back to what the maps and imagery were telling us.”
Being a digitally savvy farmer doesn’t necessarily include using drones, but it does describe those farmers who are monitoring their fields digitally and who are using crop models to make in-season decisions, says Joel Wipperfurth, a Winfield United ag technology applications lead.
Grid sampling Start
Braun and his family have been precision farming pioneers, having adopted soil sampling in 2-acre grids in 1995.
“We were one of the first customers to try grid sampling. Our local cooperative then got the equipment to variable-rate phosphorus and potassium. That got us excited about what we could do next.”
Next on the list was adjusting soil pH to help improve nutrient uptake.
“We had a field with a couple acres with a pH of 7,” he says. “But the rest of the field was 5.5 (on a 1-to-14 scale). That is not what we wanted it to be.”
Variable-rating lime enabled them to target lime to the 5.5 pH areas. “It boiled down to spending the same amount of money to lime a field and get a lot more bang for the buck. After a few years, we could see that the pH was changing, and our yields were increasing.”
Adding yield monitors and soil-mapping software in 1998 followed. Their county’s NRCS maps didn’t have the detail required to best target inputs as did precision farming maps and imagery.
A share of their farm consists of sandy and variable soils underlain by gravel. “We irrigate this ground with shallow topsoil,” says Braun. “But it does hold a lot of soil moisture.”
The remainder of their farm is the tight loamy and clay soils of southern Minnesota. Although they’re highly productive, they are slow to dry out following soil-soaking showers. “Those are the ones we keep adding tile to,” says Braun.
It’s common for all fields on the Brauns’ farm to have multiple soil types. Data layering has enabled the men to make accurate soil maps that help them target chemical, seed, and fertilizer for the best payoff.
“We have planted corn in a field with good ground that had areas with blow sand and gravel under it,” he says.
In the early 2000s, though, they still planted those areas at a field-wide rate of 29,000 plants per acre. Now, variable-rate planting enables them to plant populations between 20,000 and 34,000 plants per acre, depending on soil-production capacity.
Precision farming maps and imagery have also helped the producers with their supplemental N strategy. They begin prescription sidedressing to corn starting as early as the three- to four-leaf stage. A share of N can also be applied on irrigated ground through the center pivots.
“We keep checking N until tassel,” says Braun. If their digital N service says they need to apply late-season N, they do.
“Corn is now bred so it takes up nitrogen later in its life cycle,” he says. “So, we consider that in our nitrogen program.”
Under irrigation, sufficient water to incorporate N isn’t a concern. On dryland, though, it is. “One year while side-dressing, it was so dry where I was questioning spending money on N,” he says. “Three days later, rain fell, and we had a fabulous crop. If we err, we want to err on the side of good weather. We would rather get burned than miss an opportunity for good yields under the right conditions.”