No determinations for nitrogen or minor elements are made on routine
samples. Levels of available nitrogen change so rapidly that a soil test would
be of little value in arriving at a fertilizer recommendation. Results obtained
from minor element determinations would also be of doubtful value as no corre-
lation data are available to aid in interpretation. Recommendations for these
elements are made on the basis of past experience and land history.

 Correlation work with soil testing is never completed. New varieties and
types of crops, new farming practices, and aging agricultural soils result in
a constantly changing picture of soil fertility. Thus, minimum values of
phosphorus and potassium must be adjusted from time to time, and methods for
arriving at fertilizer recommendations must be constantly re-examined.


























EES 58-16
200 copies


-)0 3 t -b