"Depending on management style, this method of calculating K needs might not be the best long-term approach for managing K fertility, but in drought years it is often the best option for growers because of the variability in soil sampling," says Heggenstaller. "I still recommend that producers test soils this year because it will prove useful when determining future fertilizer needs."
Other key nutrients, including phosphorous (P), should not show as much variability in soil tests as a result of drought. Phosphorus does not get fixed in clay soils to the extent that K does and is not nearly as abundant in crop residues as K. In the case of nitrogen (N), most producers applied enough to achieve a high-yielding crop in 2012, but ended up receiving little precipitation and lower than anticipated yields. In these fields, it is very likely that extra N is present in the soil. Depending on rainfall between now and next spring, some of this N may be available for next year's crop.
Lack of water also may cause a drop in soil pH from previous years. Without precipitation, lime applied to help balance pH in spring 2012 cannot infiltrate the soil and take full effect. Additionally, dry soil conditions are often associated with increased salt concentration at the soil surface, which can also result in lower than expected pH test values.
Consult your local DuPont Pioneer agronomist or Pioneer sales representative to get the latest information on what is best for you and your fields in 2013. Find more information about soil testing and other topics at DuPont Pioneer's website.