Variable-rate seeding, or VRS, is the practice of dynamically adjusting the amount of seeds planted in areas of fields based on location-specific information on fertility and other factors that affect yield.
Advanced technology continues to push the limits and allow growers to optimize every resource. With variable-rate programs, growers have the opportunity to use crop data and focus resources to maximize plant health, ensuring efficient use of inputs. These programs include fertilization, seeding, and weed control as well as the application of water to farm fields.
Don't let the word “advanced” be intimidating. The implementation procedure is really not much different than determining a regular yield goal, and it requires basically the same information. While VRS requires a bit more crop management, the return on investment could truly exceed expectations.
If you are thinking about starting a VRS program, here are 5 considerations to better understand the process.
Availability of Water
Whether or not a field has irrigation influences VRS decisions. Dave Swain, manager of precision farming technologies at Southern States Cooperative, says the water factor helps set population goal range. "An irrigated field typically has the potential to handle a higher population of seed."
A traditional center pivot irrigation system will apply a steady and uniform stream of water to a field. Within a single field, however, there are often many different variables that influence irrigation needs, such as soil type, topography, the shape of the field and different types of crops.
Variable-rate irrigation systems will take into account the variations in a field and apply water accordingly. With data gathered to classify and map zones on the field, GPS technology positions nozzles according to the management zone. Working from the existing retrofitted center pivot system, nozzles will turn on over drier areas and shut off over already wet areas.
The travel speed is also adjusted to account for variations in the field.
Another VRS consideration involves looking at the current methods of the grower. "A grower's fertilization practices and how aggressive they are with plant populations to begin with can affect what changes must be made in a VRS plan," Swain says. "When planning VRS, we sit down with a grower to learn their current practices and how they fit in to a VRS program."
How a variety of corn responds in its current conditions also has a large impact on the population of seed that should be planted. Because VRS involves increased seed populations in certain areas, growers have to account for that change and adjust their practices accordingly.
“Because there are more seeds, there will be more corn plants to provide for, farmers will need to adjust how you manage this," Swain says. "Simply knowing that they may need to alter some practices is the first step."
Soil sampling and testing helps to determine how the soil will react to a larger population, so agronomists will study the results to map out where the best yield potential lies. "Analyzing the soil will tell you if you have an opportunity for a higher return," Swain says.
You won't need additional soil tests if you already practice site-specific or grid sampling. Composite samplers might need to change their sampling methods, however.
Soil that has favorable nutrient content and moisture levels can actually handle an increased seed population. Using a higher seed count on more productive areas of fields and a lower seed count on less productive areas helps growers take full advantage of their land, maximizing their seed investment and increasing their crop's productivity.
Swain says that VRS attempts to match seeding rates with soils that can handle a higher seed population. "Under favorable conditions, seeds do not rob each other of nutrients, moisture and other inputs." "It's when seeds compete for inputs that productivity is compromised."
State of Mind
Growers starting a VRS program should keep in mind that different populations have different needs. "You may have to change how the population is managed under VRS," Swain says.
For instance, higher populations of seed may need additional nutrients to reach their full potential, and growers should stay alert for any problems in the field, as denser populations of plants may increase the possibility of disease issues as well.
Still, even if VRS requires a bit more crop management, the payoff is well worth it. Overall, the results of the Southern States VRS program for corn have been positive. "We've had great responses so far and the market for VRS continues to grow," Swain says. "It's proving to be a good return on investment."
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