Ashburn, GA, (very close to Heaven!) | I have had talks with our state specialists on liming. Their target pH is 6.2, and begin to recommend lime below 5.8. I contend that my highest yields come from fields testing 6.5 to 6.9. Yes, they admit, that may indeed be so, but they present two arguments against that as a target pH: 1) a man who limes to a target pH that high is doing a lot of other things right! Indeed, the credit may not go to the higher pH, but other common denominators; 2) even if liming to 6.5 presents a good agronomic performance argument, there may be less of a cause for an economic justification. Maybe this makes sense.
Personally, I never stop at just pH when deciding on lime recommendations. We have soils that are 6.2 pH that are only sitting at 500 lbs calcium and maybe 60 lbs magnesium. This is LOW, and often is some poorer performing fields. I recommend a ton of dolomite here, regardless of buffer. Lime is such an effective source of calcium and magnesium.
Zinc? Yeah, that's nothing to ignore. Cotton is not a very heavy user of zinc, but we put a little out. Peanuts can run into problems of zinc toxicity. Corn needs it, sometimes we put out as much as 6 pounds in preplant fertilizer. I did some work for a grower a few years back who was a big user of IMC 5-10-15 Corn Rainbow Special (yuck, overpriced stuff....), and to get enough potash out over the years to make a corn crop under pivots, he was overdoing with the zinc, and it was beginning to show in the peanuts, another reason to keep pH levels in the upper 6's.
I just can't imagine how a crop can do a very good job scavenging nutrients needed in such low pH's, but grasp the concept on things like sorghum and soybeans. I can also comprehend that some of those higher buffered soils that require more lime to bring pH's up may affect economics. This is why it pays to use a good agonomist that is familiar with your crops in your region. |
Lime application
