What is Variable-Rate (VR)?
Variable-rate technology enables agricultural producers to apply different rates of product at different locations across a field. Variable-rate applications require the development of zone maps, which break the field into multiple management zones that have similar properties, allowing hilltops, midslopes, and depressions to be treated separately. The overall goal of variable-rate fertilizer and seed prescriptions is to apply the right rate in the right zone.
Variable-Rate vs. Flat-Rate Applications
Requires variable-rate capable equipment and zone maps
Allocates nutrients where they will have the best response and therefore a greater ROI
Boosts productivity, efficiency, and profitability
Improves crop yield, quality, and standability
Improves long-term sustainability and soil health by minimizing over-application of nutrients where they aren’t needed
Maximizes production of each acre of land
Does not require any specific equipment, software, or procedures
Applies nutrients uniformly; some areas will have excess, some will have sufficient, and some will not have enough
May cause lodging, delayed harvest, and difficulty during fungicide and harvest staging
May cause nutrient loss due to volatilization, denitrification, and leaching
Unable to treat problem areas such as eroded knolls, saline depressions, acid or sodic soils
All these problems relate to limited crop yield, quality, and therefore, profit
Variable-Rate Fertilizer and Seed
The goal with variable-rate seeding/planting is to produce a consistent plant stand across the whole field to even out maturity. This requires increasing seed rates in areas of lower germination and reducing seed rates in areas of good germination. The seed rate is determined by the zone and factors that affect germination such as salinity, soil moisture, topsoil depth, etc.
The goal with variable-rate fertilizer is to apply nutrients where they have the highest chance for response and thus, optimize ROI. Determining fertilizer rates depends on the yield potential and fertilizer response of the zone. It is important that the zone map properly groups areas of the field that have similar response characteristics so the variable-rate fertilizer program can be successful.
Top-Dress Fertilizer (Liquid or Granular)
Variable-rate technology provides the opportunity to manage variability in-season as well. Variable-rate top-dress applications of nitrogen or sulfur often utilize NDVI imagery and zone maps to delineate areas important for application. Top-dress applications are dependent on water driven yield potential since response to nutrients is primarily driven by soil properties and water relationships.
SWAT MAPS is the World's Leading
Variable-Rate Fertilizer and Seed Program
SWAT MAPS are management zone maps derived using multiple layers of field data including soil, water, and topography factors.
Due to their ability to delineate yield potential and nutrient response, SWAT MAPS enable us to apply proven soil science principles spatially within a field and at a higher resolution of management compared to traditional field management practices.
Other Variable-Rate Applications
Variable-rate applications of herbicide, pesticide, fungicide, or plant growth regulators enable producers to target specific problem areas of the field. The use of variable-rate technology when spraying enables growers to apply the correct rate of chemical in each zone to control weeds, pests, diseases and avoid potential carryover to other areas of the crop. Reducing chemical use also supports long-term sustainability of the field and the general environment.
Variable-rate irrigation is the ability to vary water applications spatially across a field during the growing season to optimize water placement and therefore, crop growth and yield. SWAT WATER technology creates variable-rate irrigation maps, which enables a grower to precisely manage soil moisture variability. Zone maps that include a complete indicative measurement of soil moisture conditions throughout the crop rooting zone are extremely valuable for risk management and decision-making.
What People Say
“We farm a variety of soil types and topography usually in the same field and SWAT MAPS variable-rate fertilizer and seed prescriptions have really helped us improve plant stands and even out crop maturity across those fields. Crop grades, grain moisture, and straw management have all improved with variable-rate seeding and fertility.”
“Our whole farm has been mapped with SWAT MAPS variable-rate. Our soil and available water changes in short distances on our land and the SWAT MAPS system delivers high-definition maps representing the fields.”
“Compared to other variable-rate programs, SWAT MAPS just do that much more. They have all the pieces of the puzzle there. Lots of companies are missing key things; some don’t soil sample; some just use imagery or yield data. They are missing the boots-on-the-ground that the partners provide for the grower.”