To avoid erroneous soil test results, soils should not be sampled when saturated. In sandy, well drained soils, significant leaching has probably occurred. In these soils, early reports indicate pH values may actually be lower than expected, and therefore lime requirements are greater than expected. Again, proper soil sampling is the only way to know if significant losses have occurred. Any downward change in pH is caused by leaching and will not reverse itself as soils continue to dry. .
Soil erosion can also affect soil test results.
In particular, reduced tillage fields where non-mobile nutrients and lime can stratify in the upper few inches of soil, loss of even a few tenths of an inch of soil could have serious impacts on soil fertility. Where serious erosion has occurred it may be necessary to close the gullies, replace the topsoil if it has been deposited nearby, and level the area. The soil should not be worked until dry enough avoid compaction. Soil sample after reshaping, and fertilize according to soil test. If a half inch or more of materials differing in texture from the surface soil have been deposited by flood waters, it may be beneficial to shallow till the land prior to the next crop or when conditions are dry enough to support normal traffic.