Garth Donald discusses the nutrients left in the soil in fall 2009. With the way the weather’s been, the nutrients left in the soil are quite variable. Some crops were not planted at all, some were drowned out early on, others were hailed out, and some produced near bumper crops. Trying to predict the nutrients left based on what was put in last fall or this spring is a futile endeavor.
This article emphasizes the importance of GPS points when soil sampling. We’ve found that GPS points are most useful in ensuring that areas of the fields with higher nutrients levels are avoided, e.g. old farm sites. Our current GPSes only have an accuracy down to about 3 meters, so trying to return to the exact same spot is not really practical. Even with higher levels of accuracy, returning to the exact same spot is problematic. If there has been any variability in nutrient application one spot or a small group of spots will not give an accurate picture of a field’s nutrient status. Most of our clients are more interested in a good whole-field average, though for higher-value crops zone sampling may give a better payback.
In any case: “Don’t Guess, Soil Test!”
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