INTENSIVE SOIL SAMPLING NOTES
NuWay Cooperative offers both 2.5- and 5-acre soil sampling options. This is the most intensive field nutrient management option we offer.
General overview of the process
The fields are intensively soil sampled using GPS technology. Each field is divided into 2.5-acre (or 5-acre) sectors, with a geo-referenced point assigned to each grid. At the geo-referenced point within each 2.5 (5) acre sector, multiple soil sample cores are taken and combined into a composite soil sample that represents each 2.5 (5) acre grid, resulting in multiple, geo-referenced soil tests for each field. Soil sample points are geo-referenced so that the grower can return to the exact point at some later date, re-sample, and gauge the effects that the soil fertility program is having on the soil nutrient environment.
With this soil sampling technique, growers usually apply commercial crop nutrients using a variable rate approach, meaning that more nutrients are applied where they are needed and less are applied where they are not needed. Many different factors are used to determine how much is applied to each area within a field. These factors include:
- The different soil types within a field and the corresponding yield goal for each soil type.
- Crop nutrient removal credits.
- Soil test nutrient levels.
- Applicable nutrient credits.
- Build rates used to increase low soil test nutrient values to an optimum level over a period of time.
- Draw-down rates used to decrease high soil test nutrient values to an optimum level over a period of time.
Commercial crop nutrients are then applied using satellite-guided, computerized equipment so that these inputs are accurately applied at the proper rates in the proper locations within a field. As the field is variable-rate spread, an “as-applied” map is created, documenting how much was actually spread in each area of the field. This allows a grower to track how much of a given nutrient has been applied to an exact area within a field over any given period of time.
What growers receive from intensive soil sampling
Growers receive a “base book,” showing the field location at the section level using an aerial image as a background, a soil type map, and a standard yield goal map for both corn and soybeans. See Sample Base Book.
They also receive a “nutrient book” with maps for N, P, K, Zn, pH, and OM. There is also a map showing each geo-referenced point location in the field where each soil sample was taken. See Sample Nutrient Book.
Multiple crop nutrient recommendations are automatically produced for each field after intensive soil sampling. We use a 10-rec system, where 10 recommendations are produced for each field in 10% increments. Our 100% rec would be what would be applied in an ideal situation, followed by a 90% rec, an 80%, etc.
Our recs are split out in this fashion in order to match a rec level to the producer’s nutrient budget. Recs can be mixed and matched, meaning that a person could use a 90% phosphorous rec, along with a 70% potassium rec, if the field calls for it.
Why intensive soil sampling?
Most, if not all fields have both higher-than-optimum soil nutrient levels and lower-than-optimum nutrient levels within the same field. With commercial crop nutrients costing more than ever, it is extremely important that the nutrients purchased are used as efficiently as possible.
Your Account Manager can help you get started with intensive soil sampling and VRT Application. Or, contact site-specific specialist Jeff Crissinger.