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Soil Health

Now is the Time to Start Soil Sampling

By Jonathan Hall

Soil testing provides a quick, efficient, and reliable way to map and track nutritional variability within a field and pinpoint areas requiring the most attention. The goal is to use the soil tests to efficiently apply fertilizer using the 4Rs of Nutrient Stewardship:

  • right source, at the
  • right rate, at the
  • right time, and at the
  • right place


4rs nutrient stewardship


After the historical amount of rainfall the nation experienced this year, soil sampling will be even more critical going into next season. Historical testing shows soil nutrient levels are being depleted and falling below optimum levels, preventing crops from achieving maximum yield potential and reducing maximum ROI (return on investment).



While soil sampling can be done throughout the year, late summer through early winter are optimal times for sampling in preparation for the upcoming crop season. Regardless of when you sample, it is important to be consistent with sampling calendar dates and understand how changes in the soil profile may affect soil data results.


For example, soil pH levels can vary during the growing season due to changes in CO2 levels, presence or absence of organic matter, nutrient levels, and fertilizer application. In addition, nitrates and sulfates are leachable elements. The concentrations of these elements can fluctuate due to soil type, weather, or moisture levels. Sampling during late summer, fall, or early winter helps farmers prepare for the upcoming crop while minimizing interference by any logistical or environmental hurdles that can arise during the beginning of the following crop year.


There are two main ways to sample soil – grid sampling or zone sampling. In general, grid soil sampling is preferred given its higher resolution, whereas zone sampling can miss areas of the field that would otherwise greatly affect decisions about the amount and placement of fertilizer. Also,  the size/shape of the zones can change year-to-year, leading to inconsistencies. If there is little to no soil data for a field or the field has experienced a drastic change (land grading, flooding, etc.), grid soil sampling is the preferred method to capture as much information as possible. Zones can be established based on at least three years of spatial yield data per crop or soil characteristics (texture, type, etc.) that have been proven to be highly correlated to yield variability.


Regardless of how your field is sampled, Pinnacle’s precision ag tool, OptiGro®, compiles all the data that is collected in one place. Our expert agronomists will help you customize a precise fertilizer plan to maximize yields without over-application. The results: optimal input efficiency and a more fertile growing environment. Contact your Pinnacle sales representative today to learn more about how to get your soil sampled.

Jonathan Hall

Jonathan Hall serves as Pinnacle Agriculture’s Precision Agriculture Specialist. Since joining Pinnacle in 2012, Jonathan has worked closely with our retail locations and farmers to implement new technologies and management practices to maximize yields. He also works directly with research and development to evaluate new seed varieties and products to optimize their performance on our farmers’ acres.