Prescriptive Practices

February 2, 2018 10:57 AM
Prescriptive Practices

How many prescriptions can you effectively place on a single acre? That’s a question farmers routinely ask Cory Gilbert when they want to begin using variable-rate practices. Most are surprised by his response.

“We haven’t reached a limit yet with proper planning and management in place,” Gilbert told farmers at the Farm Journal AgTech Expo.

Before using prescriptions, he says farmers must have already implemented solid zone management practices that provide a stable data set and a spatial soil-sampling program. Don’t underestimate the value of your data set and soil sampling practices—they are the basis for every prescriptive decision you’ll make.

“With those in place, you can begin to analyze the value of the prescriptions because all yield variability is either soil related, management influenced or environmentally driven,” explains Gilbert, owner of On Target Ag Solutions, Burlington, Colo.

Gilbert has come to expect a 5-bu. to 7-bu. increase in a side-by-side variable-rate pass next to a flat rate pass using the same amount of inputs, whether nitrogen or seed, just because of the field’s variability.

Here are four additional takeaways from his presentation.

  • Soil sample frequently and from the same location in each field. This will allow you to benchmark soil test data so you can measure any trends. A lot of profitability or savings lies within this data. “We run a soil test every year for every crop,” Gilbert says. “Some farmers ask how we afford that, and I tell them we can’t afford not to in order to run multiple prescriptions.”
  • Know your equipment limitations. This is important because the job your equipment is capable of doing or not doing will drive the types and number of prescriptions you can use. If your equipment is a limiting factor, see if you can tap into your service providers’ equipment and technology. “Getting your pH right can be accomplished with a dry spreader, so don’t overlook this opportunity,” Gilbert says, as an example.
  • Set goals. If you’re new to prescriptive practices or have limited capability, Gilbert says to focus your first steps on nitrogen use and seeding rates. Manage seeding rates based on water-holding capacity or low- and high-yield areas if soil data is limiting, Gilbert advises. Light soils or areas with limited water-holding capacity can’t sustain the same plant populations as heavier soils with better water-holding capacity. Often, the lower seeding population can increase yields in light soils. As for nitrogen and other nutrients, the only way to optimize levels is through a soil test. Based on the results, you can identify potential savings by avoiding overapplication or yield loss from a deficiency. “We have seen phenomenal results with variable-rate fertility programs, reducing rates by over 25% in some cases and still exceeding our yield goals,” Gilbert says. “We set out to apply the optimum rate of every nutrient the client has the ability to control, whether it is applied pre-plant, via the planter or in-season. Our average field has three products applied using variable-rate technology and some have as many as six per season,” he adds.
  • Stay the course. Once you set goals, stay with them. Human nature often causes farmers to jump from goal to goal or from platform to platform, Gilbert says. But staying consistent is the only way you can learn what works in your fields and achieve long-term results from prescriptions that can improve your bottom line.
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