Vigilance in Soil Testing and Scouting
Crop advisors are constantly looking for ways to improve soil testing and scouting strategies. CropLife® magazine looked into a sampling of the latest technologies that suppliers and users are recommending to help.
Where do soil tests stand these days? Beyond revealing trends and outlier situations, soil tests can now be used as a true precision prescription tool, says Rich Wildman, Managing Member, Agrinetix. They commonly refine fertilizer treatments down to plus or minus 50 pounds per acre.
Cutting-edge producers are continually refining their soil sampling, he points out. Grid or zone sizes are shrinking rapidly, and the most advanced producers are currently managing at the 1 acre grid size. Some are experimenting with 0.5 acre grids.
The value is clear: Sub-field management grids or zones provide a much higher ROI than whole field sampling.
“In our experience, producers save $50-plus per acre in fertilizer costs when they sample at the 1 to 2.5 acre size,” he says. “And in our experience, producers see noticeable yield increases when they fertilize at the 1 to 2.5 acre level.”
The vast majority of corn producers do broad-spectrum soil tests, which check everything from pH, CEC, P, K and base saturation levels, but the frequency and the density of the sampling varies. “Fertilizer retailers often do a minimal level of sampling every second or fourth season. But less than 25% of producers (not acres) do extensive grid or zone testing every other year,” says John Larkin, Marketing Director with the 360 Yield Center.
Soil testing does save money on P and K applications in the long run, says Brandon Lesage, Client and Service Representative at SGS North America. It allows growers to build up weaker parts of their fields, which over time will reduce the amount of fertilizer needed. “Short term it allows you to just apply maintenance levels on your more fertile areas, thanks to VRT,” he says.
With advances available today, growers can go beyond grid sampling, says Tyler Lund, Director of Sales and Marketing at Veris Technologies.
“Grid soil sampling is like a doctor trying to find cancer by taking a biopsy sample of the patient’s nose and their toe,” he says. “Soil mapping with on-the-go sensors is like an MRI that can scan the entire body and see beneath the surface to find the tumor. Lab samples are still crucial, but we need to know where to take the samples.”
Lund has found growers who were previously satisfied with precision ag — including using grid sampling for P and K applications — are realizing they’ve outgrown these maps. As they move toward variable-rate seeding and improved nitrogen management, they see the need for higher-resolution soil maps. Veris soil sensors mounted to tillage tools and planters, as well as on utility vehicles, can collect that kind of precise soil data.
Another specific situation where these in-depth maps can help? Iron deficiency chlorosis (IDC) is a significant issue in soybeans grown in regions where high pH and saturated soils are common. “It’s costly to treat an entire field when only a portion is needed, and you’re too late if you wait for symptoms to show up,” he says.
A predictive tool for identifying potential IDC hotspots is now available from Veris in its FieldFusion software. The tool helps with recommendations for tailored micronutrient applications to address a costly issue.
More Sample Uses
360 Yield’s Larkin says his firm advocates taking an additional sample that looks specifically for nitrates during the growing season — and perhaps sampling multiple times during the growing season — to identify the volume and location of the nitrates just prior to and during the rapid uptake cycle of the corn plant.
“We’re looking to measure the available nitrate levels to ensure that there are enough to finish the crop,” he says. “If there has been nitrate loss, we determine how much is needed to refuel the soil. If there has been good mineralization and an abundance of organic N, we can eliminate or reduce the final N application accordingly.
“By reducing the amount of N used before planting, and shifting those applications until closer to the time of use by the plant, rates can be adjusted to maximize efficiency based on the weather and growing environment.”
At press time Larkin had a word of caution for the 2018 season. “We’ve had the wettest February on record here in central Illinois and down through Kentucky and Tennessee. Our soil temps were at 50 degrees,” he says. “That is a bad combination for fall-applied nitrogen. The conversion from the stable ammonium form to the mobile nitrate form is taking place and the rains can flush the N away. This kind of February and March should put us on alert for high levels of N loss by the time plants need it just prior to tassle.”
Mark Anderson, President of GVM, believes growers should look more deeply into one thing soil samples can show: yield removal. What nutrients did a crop take out of a field?
“Right after harvest, you want to take soil samples and get your yield and soil sample maps together to get the exact fertilizer recipe you need,” he says. “Get it done in the fall before the ground freezes, and the opportunity to go out and spread fertilizer passes. That gives you a very short period of time, a very small window.”
Indeed, some of today’s technologies, such as GVM’s AgriWave cloud-based management system, can help analyze samples, generate fertilizer recommendations, then apply product in as little as 72 hours, he says.
There may not be one single test or process that is a silver bullet, says John Menghini, Certified Pro-fessional Agronomist with Midwest Laboratories. He says soil testing has been an excellent option for many years, as it offers insight into soil fertility and whether a crop will respond to fertilizer application.
“Many additional options complement soil testing, including plant analysis, deeper nitrate samples at sidedress, and stalk nitrate tests at the end of the year. The new nitrogen modeling tools can be used in conjunction with soil tests to help determine nitrogen rates,” he says.
Menghini has found that growers’ reasons for testing differ. There may be more of a drive to sample soil in regions where yield potential is much higher than areas with limiting factors. Cropping can also impact the decision, and decisions to test on leased ground can vary. Notably, he feels increased regulations on products such as fertilizers and manure will dictate sampling in the future.
Scouting fields also remains a key part of protecting yields, and the newest tools here can tie vital information together for retailers.
Erich Eller, Owner of ForeFront Ag Solutions, Huntington, IN, has spent the last two years experimenting with how to best use UAVs for his customers. He’s officially offering the service in 2018. In fact, his drones will be making five to six passes over fields, creating NDVI files of the crops’ levels of photosynthesis, with the goal of spotting plant stress — then ultimately tying image results back to yield. Season-long field data is collected and analyzed in EFC Systems’ FieldAlytics and FieldAlytics Explorer.
He’s found the cameras can pick up weaknesses even in areas that appear green and healthy.
Eller flies an AgEagle Rx60 and AgEagle Rx48. He appreciates their flexibility and the option of changing out sensors (cameras). The UAVs can fly in more adverse wind conditions, according to the company, and can cover more acres on a battery charge. Eller says AgEagle’s back-side support “has been amazing — that’s why we bought our second one.”
Scouting can pay off for an entire territory. In 2017, in particular, counties surrounding his clients’ fields had been seeing Southern corn rust, and Eller was concerned. He sent suspicious leaves to Purdue’s plant pathology labs. Although samples came back as common rust, such careful tracking and communication proved valuable.
Disease scouting is becoming more important as growers look for ways to trim costs, he says. “Broad-acre spraying of fungicides will be reduced,” Eller says. “A case-by-case application is possible, with scouting leading that recommendation.”
On the insect front Eller is excited about the newest electronic insect traps. The Z-Trap from Spensa captures pests, and users can log in to see growing degree units and trends in catches. “We can combine these results with UAVs and focus our scouting effort more effectively,” he says. “We are in talks with some neighbors, working on putting together a network of these. Five traps are good but 50 or more would be great.”
The network would be especially helpful this coming season, as Western bean cutworms have been showing up in Indiana and can cause a fair amount of damage. “As growers have reduced the use of Bt corn and popcorn acres, scouting becomes key,” he points out.
ScoutPro continues to develop its app. The system already interfaces with the Winfield R7 platform and Agvance software, and the company is finishing up integrations with a number of other systems, with public release anticipated for the start of the growing season.
ScoutPro’s Directed Scouting system can now consume a variety of imagery — which can include not only satellite and drone files but also planting maps to bring in soil zones if needed. “It’s using another right map for the right time of year,” says Stuart McCulloh, Director of Customer Success.
With today’s economy, he sees growers needing to justify all field treatments, and that’s where his firm’s system can help. For instance, users can pull up easy-to-view scouting reports from previous years on the company’s web service to see what they may need to watch for.
“Overall we’ve continued to focus ourselves — to just do scouting. We want to be a very, very sharp, concise tool,” McCulloh says. “Our customers don’t use ScoutPro just because it’s a free or it may be free tied to a seed purchase or anything. Our folks find value in the quality, consistency, and scalability of our program.”