Troubleshooting Soil Fertility Problems Follow the recommendations, keep soil pH in the proper range and know what to look for when problems arise. By Amanda Huber
S
oil is a living ecosystem and is a farmer’s most precious asset. A farmer’s productive capacity is directly related to the health of his or her soil — that’s a quote by Howard Warren Buffett, farmer and former special assistant in the U.S. Department of Agriculture, who is also the grandson of American investor and philanthropist Warren Edward Buffett. If something is alive, it has to be fed and taken care of, and that’s true of the soil. To get the best out of it and make a top-yielding peanut crop, the first place to start is with a soil test, says Glen Harris, University of Georgia soil scientist. Harris’ general peanut fertilization recommendations are as follows: soil test and follow those recommendations; add lime as needed to have a soil pH at 6.0 to 6.5; build soil phosphorus and potassium; inoculate if the field has been out of peanuts for more than four years; provide calcium to the pegging zone; and apply 0.5 pounds of boron per acre. “If you do these things, soil fertility should not be your limiting factor from making good yields.” However, there will be times when troubleshooting field issues will be necessary. Harris says when investigating problems in the field, the process of elimination always seems to be herbicide, disease, nematode, a seed issue, insects, and when those are ruled out, fertility is likely the answer. Catch Problems Early “Try to catch problems within 30
16 /
THE PEANUT GROWER • MAY 2021
The No. 1 soil fertility problem in Georgia is low soil pH. This field shows a pH of 5.7 on the right and 4.9 on the left.
days after planting, especially things like nitrogen or inoculant failures. Look for overall patterns in the field. If it’s streaked or ‘to the row’ that would indicate problems with the planter or spreader truck. Is the problem on the field edge or in weak spots? “Look for symptoms on the plants. Is it on new leaves or old ones, top or bottom of the plant? Look at the roots to see if they have been inoculated and are nodulated by bacteria to fix nitrogen. “Make sure you are keeping a record of planting date, varieties, timing of symptoms and whether you had unusual weather patterns. All of this information can be helpful when trying to figure out a field problem.” Consider Grid Sampling, VR Lime Harris says the No. 1 soil fertility problem in Georgia is low soil pH.
“Dr. Eric Prostko would agree with this. He gets a lot of calls for what the farmer thinks is herbicide damage, and it turns out to be low soil pH. “In fact, there are not many problems in soil fertility that will flat out kill plants, but one that will is a soil pH below 5.5. Especially at a level below 5.0 to 4.5, peanut plants will certainly die,” he says. Harris says grid sampling and variable-rate lime applications are a good way to create a more uniform soil pH in the field, although it is not an official recommendation yet. “Grid sampling and variable-rate lime is a good way to fix a lot of problems we’ve been seeing. There tend to be spots in most fields that will be lower in pH, and if you keep putting out the same rate of lime every year, then the bad spots keep getting worse over the years. PEANUTGROWER.COM
