2018
HARVEST GUIDEBOOK
endall Kirk, Clemson University agricultural engineer based at the Edisto Research and Education Center in Blackville, South Carolina, has conducted extensive tests on reducing peanut losses during digging, and has some advice that growers may want to consider. Most digging losses are due to weakened peg strength, diseases in the peanut plants, harvesting when peanuts are overly mature and mechanical interactions between the soil and the digger, according to Kirk. He says many digging losses can be reduced by digging at the proper time and by correctly adjusting the settings on the digger. “You’re always going to have some variability in maturity,” Kirk says. “There are almost always some pods that are over-mature, so some of these losses are inevitable.” It’s a sad fact that some digging losses are inevitable, according to Kirk. He cites studies in Texas that showed that even with favorable soil conditions, and proper adjustments on the digger, there were still 400 pounds per acre losses from digging. In Kirk’s own research, he recalled a study in 2013 on Virginia varieties. It
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Photo credit: Kendall Kirk, Clemson University.
Cut Digging Losses Many digging losses can be reduced by digging at the proper time and by correctly adjusting the setting on the digger.
showed that even with proper digger settings, there were still 580 to 1,200 pounds per acre lost during the digging process. He says that amounted to per acre financial losses of $150 to $300 per acre, or about 9 to 22 percent of the total production that was lost during digging. When Kirk talks to peanut farmers, he often shows a pie chart. It shows that for a typical peanut field, about 75 percent of the total peanut production in the field is harvested and brought to market, while about 23-24 percent of the total production is lost during digging, yet only about 2-3 percent of the total production is lost during the combining phase of harvesting. Determining the amount of losses from digging is time-consuming research, according to Kirk. He, his colleagues and student workers collect peanut pods in sifted soil from within rectangular frames placed behind the digger. “You can sometimes see visual indicators of digging losses, and see if your digging is at too shallow a depth or too deep,” he says.
Southeastern Peanut Farmer July/August 2018
For instance, if the vines for two rows within a section of the digger tend to ride inboard, that can be an indication that you are digging too shallow. Soil texture also impacts digging losses. “In the Southeastern coastal plains, we see a large variability in soil texture,” Kirk says. “The common practice is to set the digging angle of the heaviest soil in a field.” The top link connecting the tractor to the digger is what sets the digging angle. He says that in clay soils, farmers should use a more aggressive angle for the digger while in sandy soils, a less aggressive angle should work best. “The best advice I can give for reducing digging losses is to cut the taproot of the plants just below the pods,” Kirk says. “If peanuts are dug too shallow, then some of the pods will be sheared by the blades and some pods will be left in the soil. This often occurs when the top link adjustment is too long.” Across different soil types, Kirk says fixed digging angle with no hitch adjustment can result in farmers digging