Variable rate
What is variable rate application?
Variable rate application changes the amount of product applied as a machine moves across a field, using a map, a sensor, or both.
Topics
Variable rate, explained
What variable rate application is, and the maps, soil tests, and equipment words that sit next to it.
Variable rate
- What is a flat rate application? A flat rate application puts the same amount of product on every acre, from one end of the field to the other.
- Map-based and sensor-based variable rate Map-based variable rate follows a file loaded before the pass. Sensor-based variable rate sets the rate from a reading taken while the machine is moving.
Maps
- What is a prescription map? A prescription map is the plan for a pass: each part of the field has a target rate for one product, written before the machine leaves the yard.
- What is an as-applied map? An as-applied map is the record of what the machine put down during a pass, logged while it was moving.
- What are management zones? Management zones are areas of a field grouped because the soil, the crop, or the lay of the land behaves in a similar way.
The field
- Why rates differ across a field A single field can hold sand and clay, wet ground and dry ground, and a hill and a low spot, so one number does not describe every acre.
- Yield maps and yield monitors A yield monitor records grain flow, moisture, and position during harvest. A yield map is that record drawn back onto the field.
- Crop canopy and vegetation indexes A vegetation index turns satellite or sensor light readings into a number for how much living canopy a spot had.
Soil
- Grid sampling and zone sampling Grid sampling lays soil cores on equal squares. Zone sampling lays them on management zones. Both send mixed cores to a lab.
- Soil surveys, slope, and electrical conductivity Soil survey maps, slope, and electrical conductivity are three pictures of how the ground itself changes inside a field.
Fertilizer
- Variable rate fertilizer Variable rate fertilizer changes the amount of a nutrient product from one part of a field to another during the same pass.
- Variable rate lime Variable rate lime changes the lime rate across a field so each area gets the amount written for its soil pH.
- The 4Rs of nutrient stewardship The 4Rs name four decisions in nutrient use: source, rate, time, and place.