Stemming from another current discussion Ground moisture vs. LPAM antenna performance a search led me to this report concerning the increasing salt levels in our ground (which so happens corresponds with increase range of AM propagation) is killing plant life.
The Salts of Our Soils
https://lists.ibiblio.org/sympa/arc/livingontheland/2006-11/msg00121.html
(Heavily truncationated version)
A case can be made that the salt levels in our soils may be increasing from the deposition of atmospheric aerosol reactive metal salts over time1. Numerous measurements of soil samples in the northern New Mexico region are showing relatively high levels of conductivity. Conductivity is a direct measure of the concentration of ions in solution. Reactive metal hydroxide salt forms, such as those that have now been documented at unexpectedly high levels in both the atmosphere and rainwater2, are exactly the type of salt forms which will increase the conductivity (ion concentration) of the soil as well. The importance of this finding is that increased salt levels in the soils will lead to stress on the plant life...
...The best reference for expected conductivity levels in the soil on a nationwide basis found this far is a map issued by the Federal Communications Commission5. This effort was published in 1954 on a nationwide basis, as the conductivity of soils is a significant factor in AM radio propagation. Although general, the source nevertheless represents a major national effort that apparently has not been duplicated since. Conductivity maps and profiles are important as they are one of the best indicators of salt levels that are expected in the soil. There are numerous sources...
....Compounding the problem, we must now consider the effects of aerosols that eventually accumulate in salt forms within the soil from precipitation and gravity. This paper considers the effect of precipitation alone... The conductivity levels in the immediate vicinity of the now dead trees appears to be unexpectedly high. Calcium and magnesium components are two of the primary ionic salt forms that now are being identified at high levels in rainwater tests. If ionic exchange and ion concentration processes are taking place in the roots and soil in the vicinity of the trees, it seems conceivable that a process of soil saline concentration and accumulation is occurring. If the levels are high enough, and the testing results at hand indicate that they are, then it is quite possible that saline stress is an active process - here and now... There is no claim here that saline stress is the cause of all of our woes in the plant world. This paper, however, does raise some questions that deserve fair consideration with respect to the massive global effects from the aerosol operations. There is no doubt that global effects are occurring, and many of them have already been, and they continue to be, measured....