Soil Sampling: Customization Remains The Key For High Yields

While fertilizer prices have trended lower in recent months, they remain historically high and a cause for concern as growers close the books on the 2022 crop year.

“Farmers are crunching their numbers, but they can’t forget that when they harvest a crop, they’re taking nutrients off the acre, and those nutrients have to be replaced for the next crop,” says Nathan Barnett, Regional Manager, Ag Technologies, for GreenPoint Ag.

“In years past, we might have sampled using a 2.5-acre grid approach on the whole farm. Some growers sample on a rotation, and while we may be in an off year, we need to be addressing our fertility issues with some form of sampling.,” Barnett said. “At the end of the day, good yields are what’s making us money, and if we’re not putting fertilizer back in our soils, we’re hurting ourselves in the long run.”

Typically, Southeast growers start pulling soil samples as soon as crops are harvested or cotton stalks are mowed, with peak sampling occurring at the first of the year, in January.

“It really boils down to a timing issue. If we can sample as soon as crops come off and finish earlier in the season, it makes our spring more manageable,” he said. “We can get lime ordered earlier and spread earlier. We’re not running around in late February or March before we begin planting corn, worried about putting out lime in addition to everything else that is going on. Not to mention, lime needs several months to fully break down and neutralize soil pH. Likewise, earlier sampling gives us longer to strategize a fertility plan and budget with our growers through AccuField’s suite of customized tools.”

If soil moisture is too dry or too wet, it will skew soil sample results. Also, if a grower is on a sampling rotation, it is important to sample at about the same time each year to avoid seasonal variability in soil tests.
While the necessity of fertilizing hasn’t lessened over the years, the methods have improved significantly, Barnett said.

“About 20 or 30 years ago, a composite sample was the simplest way to pull a soil sample, and we still pull a composite sample in certain situations, but we’ve found that with grid and maybe zone sampling, you’re identifying potential problem areas, and you’re able to address variability in the soil,” he said.
While sampling on a 2.5 to 5-acre grid might not always save money, growers can be assured that they’re placing lime and fertilizer where it is needed as opposed to applying a maintenance or blanket rate as you would with a composite sample, Barnett said.

GreenPoint Ag’s AccuField^®—a full-service ag technology and information platform—offers a premiere soil fertility tool in a precision agriculture platform.

“Through this platform, we can help a grower with grid sampling their field on a resolute basis—in 2.5 or 5-acre grids—or through zone sampling their fields using historic yield data or some data-driven approach,” he said. “This gives us an accurate assessment of what’s happening in that field in terms of soil fertility.”

Experience and research have taught, Barnett said, that sampling a 2.5 to 5-acre grid gives a more accurate assessment of what is going on in a field.

“In some areas of the South, growers are doing more zone sampling,” he said. “Rather than going out every year to every third year with a grid sample, they’re transitioning to management zones by utilizing yield and other data. This form of sampling is being utilized mostly by growers who have been grid sampling for years and have a better understanding of their soil profile and or have made strides in reducing field variability in seasons past.”

“AccuField^® is a one-stop shop for all of our customer’s needs,” Barnett said. “Our growers can view their data in one spot. We have different capabilities inside this software, and we can create customized fertilizing recommendations, planting prescriptions, in-season imagery, and many other options.

“For example, return on investment metrics are an important service focus for our customers; AccuField^® offers soil trend analyses which show how your soil fertility is trending. If we’ve been pulling samples for multiple years, we can track that and produce a chart that shows how your soil is trending with respect to each element tested.”

The more data that is available for a farm, the more opportunities a grower has within AccuField^®.

“Each year’s farm data collection adds to a grower’s database,” Barnett said. “We have so many options within AccuField^®; the more years of quality farm data a grower accrues, the greater advantage he or she has in leveraging tools within AccuField^®. Each year presents its own set of challenges. In today’s markets, we can use these datasets to ensure our fertility program is stellar and adhering to current budget demands. Next year a grower may need to pivot and use the data to make decisions regarding something different. With a strong dataset, he or she can rest assured that AccuField^® has the tools and analyses needed to assess fertility, monitor yield trends or aid in any farm-related decision.

To learn more about soil sampling with AccuField, reach out to your local GreenPoint Ag.

Written by Paul Hollis