Centre county Pennsylvania, USA | Bill, Penn State is still using Mellich III chemistry in their farm soil tests. Perhaps Olsen chemistry would give more accurate results but Penn State soil tests pulled from areas in that farm that showed no corn stunting or yellowing showed Mg levels of about 175 ppm. Most of our farm fields have average Mg levels in the 150 - 180 ppm range. The very excessive level of Mg in areas where corn was stunted and yellow at knee high is way way above the Mg levels we are accustomed to seeing with Penn State's Mellich III chemistry. I sincerely appreciate Jake's gypsum suggestion but ,like you, I am reluctant to apply the heavy dose of sulfur that comes with gypsum AND Ph is already higher than we like. I totally agree on applying high levels of both P and K in those areas, I think many (most?) soil scientists claim that Mg deficiencies are made worse by high levels of P. Mg deficiencies are badly needed in those very high Mg areas and P levels need to be much higher. Because non stunted areas in that farm have more reasonable P and Mg levels I am questioning if the very high Mg in stunted areas is causing P deficiencies in those areas ?
Because that is rented ground we are reluctant to invest very many $$ in experimentation, but we do think that farm is a very good candidate for VRT P&K. In addition, the stunted corn areas responded very well to 120# of N side-dress after knee high, plants recovered and ear development is satisfactory but yields in those areas appear to be somewhat less than planned.
Thanks Bill and Jake, I do appreciate your considered comments, we are still learning here.
Edited by Don Smith 9/15/2006 20:53
|
Magnesium levels
