What is in this article?:
• Pay attention to the price of fertilizer.
• Consider application rate and method.
• Sampling to depth is a good idea.
MARK MCFARLAND, Texas A&M professor and AgriLife Extension soil fertility specialist.
Big pH range
Some Blacklands soils show pH levels as high as 7.4 to 8, but some soils in the area may be as low as 5.4.
Again, McFarland recommends sampling deeper than the typical 6-inch level. “Sometimes the pH is low just in the surface 6 inches, which may not be a problem. But if it’s low to depth, it could be trouble. Anything below 5.6 or 5.7 will show a response to limestone. Below 5.5 applying limestone will likely provide a significant advantage.”
“It’s a good idea to test to depth.”
Tillage may be an adequate option if soil pH is low in just the top 6 inches. Mixing soil from 8 to 10 inches may correct the problem.
McFarland cautions Texas farmers to make certain of what they are buying when they purchase limestone. “There is no limestone law in Texas, so it’s up to growers to know the quality of the product. Content and fineness make a difference. Percent of limestone — 50 percent or 100 percent—affects the value and dictates application rate.”
With fertilizer prices still extremely high, McFarland says farmers can ill afford to waste any, apply more than they need, or to pay for any product that will not provide an economic advantage.
The best tool remains a thorough knowledge of soil nutrient levels — based on soil testing (including sampling at depth).
Paying attention to what fertilizer costs, he says, should drive that message home.