Is post-plant sampling the answer?

Posted on
May 9, 2022
Buffy Uglow    buffy_uglow@rockriverlab.com

By: Dustin Sawyer, Laboratory Director [and agronomy guru]

One of the most compelling arguments for spring soil sampling is that it allows for more time to plan the fertility program. This is especially important recently as fertilizer prices seem to fluctuate with the wind. But with the current weather ‘situation’ throughout the Midwest, planting, let alone soil sampling, has been largely postponed well past the typical timeframe. Post-plant soil sampling is the answer.

Being able to develop a fertility plan prior to harvest means that the amount of fertilizer needed will be known long before the year’s end. Growers armed with this information will be able to watch the market and be prepared to pounce on a fertilizer purchase if the conditions are right. That’s a much better scenario than the typical, relatively short purchasing window right at the end of the year.

Spring sampling is not to develop a fertilizer program for the crop that’s being planted that spring – it’s for next year’s crop. To that point, spring sampling does NOT need to be finished up prior to planting. Samples can be safely pulled until the time that a crop will no longer recover from being driven over by an ATV. If starter fertilizer has been applied, try to stay out of it, but when the right number of cores are pulled for each sample (8-10 cores are ideal), the chance that any applied fertilizer alters the soil test result is quite small.

Spring soil sampling not only allows for more time to plan a fertility program, but research has shown that samples pulled in spring do not exhibit statistically significant differences in soil test data when compared to fall. Plus, spring sampling takes into account the additional nutrients that come from crop residue freezing and thawing over winter. With all of these perks, growers and agronomists can find peace in switching their sampling seasonality and mindset. I suggest checking out the resources and data regarding spring soil sampling, which be found and downloaded at https://bit.ly/spring-sampling.

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