What’s Really in the Soil?

3/23/2013 7:00 AM
By Chris Torres Staff Writer

Crop Adviser Weighs Advantages, Costs of Grid Sampling

READING, Pa. — Is it worth the money to grid sample one-acre plots on the farm?

Eric Rosenbaum, owner of Rosetree Consulting, thinks it’s a no-brainer.

“Yes, grid sampling is expensive. But the cost of underfertilization is huge,” he told a group of 50 producers Tuesday at a workshop sponsored by Deer Country at the Berks County Agricultural Center.

Rosenbaum has been working with various producers in Berks County, trying to get a grasp on whether grid sampling will bring enough of a return to justify its initial high costs.

Traditional soil sampling involves taking dozens of samples from random areas of a field, say 50 acres, mixing those samples up, sending them to a soil lab and getting results.

With grid sampling, you can use that same 50-acre field, but break it down into small grid blocks, maybe an acre or two in size, take samples from each block and get results back.

The goal is to identify nutrients, soil types and other factors that could be holding back yields and prescribe things to alleviate any problems.

“I think the eventual goal is to move from grid sampling into some sort of zone sampling,” he said.

But doing grid sampling is expensive and time consuming. While a traditional soil sample on a 50-acre farm might cost between $3 and $6 an acre, it can cost up to $20 an acre to do grid sampling when you take into account the time needed to take samples and soil tests.

Rosenbaum thinks the amount of money that could be saved in fertilizer, along with cashing in on bigger yields at the end of the season could easily help to offset the cost of grid sampling.

He said it all starts with farmers getting accurate yield monitoring information, something that can easily be done with today’s computerized combines.

“We want normalized yields to show us consistent patterns,” he said.

Rosenbaum worked with three farmers in 2012, creating grids for each farm. Each farmer paid for the soil tests, but Rosenbaum didn’t charge for labor.

Like a detective, he studied web soil surveys from each farm to see the history beneath the surface.

Hopping on his four-wheeler and using his iPad, he went into each field, drawing out a grid, taking various soil samples.

He said that although it can take three to five years to get a consistent enough yield history, grid sampling can be effective to see what’s going on in a shorter period of time.

One farm he tested, a 60-acre farm where it took eight hours to draw out the grid, was split up into much smaller, 2-acre blocks. He tested phosphorus and potassium levels, along with other levels of nutrients.

He found that 26 of the 29 blocks were deficient in phosphorus, with a range of 12 to 80 parts per million. Sixty percent of the blocks were also deficient in potassium, based on average numbers recommended by Penn State to grow a corn crop.

“We’re looking at a field where 90 percent of a field has a potential phosphorus deficiency,” he said.

But it’s not just the numbers from grid sampling that are important to think about. It’s the fact that traditional soil sampling likely wouldn’t have caught this wide variation in nutrient levels, causing the farmer to overapply or underapply nutrients.

“We’re wrong 80 percent of the time, and that’s sad,” he said.

Rosenbaum estimated that overfertilizing this particular field cost the farmer about $14 an acre, based on the price of phosphorus and potash. But underfertilizing would have cost much more, $52 an acre, when you consider the current high price of corn.

“We have to be able to do it and see that increase in profitability. We’re not going to do any of this unless we can make these guys more money,” he said.

Representatives of Deer Country presented information on current products that John Deere is offering as well as future initiatives the company is working on.

Gary George, precision ag specialist with Deer Country, said the dealer is working with around 100 producers in the region on precision ag technologies.

Sprayers with bin shutoff and planters with row shutoff are popular, he said, along with combines that have the ability to do yield mapping and tractors with auto-steer.

He said many Midwest growers are already working with their crop advisers, developing “prescriptions” for certain fields and getting the necessary variable planting or spraying equipment to do it.

As systems have gotten more advanced, companies have gotten more attuned as to how to use data coming off fields, George said.

“We have the ability to collect more data and more useful information, and this is where certified crop advisers come into play, to read this data and make recommendations to the growers in order to achieve better yields, produce better bottom lines and also save on their inputs,” he said.

William Gotwals, who farms 800 acres of field crops in Oley, Pa., with his grandson, Bill Gotwals, has invested $15,000 in precision ag equipment for this coming growing season, including a new monitor for the new John Deere 7230R tractor they just purchased.

William Gotwals said he hopes the new system will help him and his family farm better and produce higher yields.

“Always on our hills and stuff, the planter would drift downhill and you would get little rows,” he said. “With this thing, the planter will know where that is and just guide itself. We have a lot of strips and hills, and it will help on that.”

Star Rock Farms, which owns or leases 12,000 acres of land in Lancaster and York counties, Pa., and in northern Maryland, has been using precision ag technology for the past seven years, according to Dave Chilcoat, who runs the precision program on the farm and has been there for seven years.

“We’ve been using a lot of this technology well since I’ve been there. We’ve been collecting yield for nine to 10 years on some farms. We’re already at the point where we have zones put together,” Chilcoat said.

Much of the equipment being used is state of the art, and there are various sensors in the fields to keep the farms better interconnected.

Now he’s looking at taking the next step and looking at technologies that could enable him to keep track of where his machines are at all times and download information from each machine remotely.

“It’s helpful to know where they are and know what that tractor’s been doing for the last week and what kind of data that I need to get,” he said. “And it would be nice to bring all of that data without me having to chase them down.”

Even though he’s seen a steady increase in yields, Chilcoat said it’s too early to say whether he’s seen a good payback from the investments.

“We definitely have seen yields increase over the last six years. I think a lot of that is due to more intensive management,” he said. “But I don’t think we’ve reached that level where we’ve been able to maximize the higher yielding areas so much. It’s a long-term process.”


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