P2O5 and K2O can remain in the soil as crop available nutrients for many years. When an over-application of phosphorus or potassium has occurred in prior years, then the Prior Years' Extra nutrients are shown in the row under the UW Recommendation for the crop, and the prior year P2O5 and K2O will be used to meet recommendations in the following years. The adjusted recommendation is the difference between the UW Recommendation and the Prior Years' Extra, or zero (if the extra is more than the recommendation). Note: Due to its susceptibility to leaching, only half of the excess K2O is counted as carryover in Sandy group soils.
The Over/Under-applications (as calculated in the Over(+) and Under(-) Adjusted UW Recommendations row) are summed from year to year until a new soil test is selected for the cropping year. The Prior Years' Extra in the year a new soil test is entered will be zero.