Glyphosate Herbicides Cause Tragic Phosphorus Poisoning of Lake Erie

[yellowcanine]

22. The P runoff appears to be a calculation, not an actual measurement.

It appears they sprayed the glyphosate on bare soil and then took soil samples and analyzed them for release of P.
It is actually a little hard to tell because the article is not a journal article - it is a popular press article with minimal detail as to methodology.

Problems I see:

1)I don't know anyone who sprays glyphosate on bare soil. It is sprayed on weeds and weeds absorb the vast amount of the glyphosate. The article did speculate about glyphosate on plant residues but imo the speculation was not well informed by actual science.

2)The article says nothing about rates and amount of water used. Without those it is hard to tell how realistic the rates and GPA are relative to actual practice.

3)Without a direct measure of P runoff any conclusions are speculative.

4)What were the P levels in the soil to begin with? This is important, because we know that it is only in soils with very high P levels where there is any risk of P runoff. It is true that no-till fields often have higher levels of P in the top several inches and this in itself might be much more of a factor than anything glyphosate might do in releasing soluble P from soil.