RALEIGH, N.C. - If a sign were placed on a piece of new ground intended for peanuts, Extension experts would simply have it read, “inoculate.”
With peanuts going into so much new land over the past two years, inoculation provides the pathway to high peanut yields, says David Jordan, North Carolina State University Extension peanut specialist. “Last year’s good yields, in many areas where peanuts were a new enterprise, demonstrated the benefit of inoculating.”
On new peanut land in two North Carolina counties — Duplin, near the central coast, and Gates in the northeastern part of the state — inoculated peanut yields were increased two and three fold.
Without inoculant, peanuts languish for a lack of nitrogen. Inoculation provides a relatively inexpensive and effective way of providing the nitrogen-fixing power required for high yields. Otherwise, peanut farmers would have to apply nitrogen fertilizer. “This would be relatively expensive compared to the cost of commercial inoculants,” Jordan says.
Simply put, inoculation puts appropriate strains of bacteria in the soil so peanuts can fix their own nitrogen. Peanuts “fix” their own nitrogen, but inoculum is rarely present in nature.
By inoculating the soil with bacteria, farmers help the process of converting nitrogen gas into a useable form so the peanuts can grow properly, Jordan says.
The bacteria infects the roots of the peanut plant, thereby beginning a relationship benefiting both the plant and the bacteria. The peanut is able to fix the nitrogen; the bacteria lives off of carbohydrates and other necessary nutrients and minerals supplied by the plant.
While native inoculant may be in the soil, especially in short rotations, peanut farmers most often apply commercial inoculants, Jordan says.
At small levels, inoculum is found in the field naturally.
Farmers can also inoculate peanuts in the hopper box at planting or with a granular application in-furrow or a liquid application in-furrow.
“In new ground, the response is amazing and clearly evident,” Jordan says. “In fields that have had peanuts in them, there may not be an obvious growth response, but sometimes there is a yield response.”
While it’s important to inoculate in a field that hasn’t seen peanuts, Extension also recommends inoculating every time peanuts are planted, regardless of rotation. “At the very least, growers should apply a hopper-box seed treatment,” Jordan says. “If rotations are longer or if you are going into new ground, in-furrow sprays or granulars are recommended.”
Stressing the importance of the practice, Jordan points to the consequences of not inoculating peanuts.
“Without inoculation, peanuts will have a severe nitrogen deficiency,” Jordan says. “Nitrogen is required for all things to grow.
“Although there may be some residual nitrogen in the soil from organic matter breakdown or from fertilizer applied to the previous crop, this is generally insufficient to optimize yields,” Jordan says.
The bottom line to not inoculating is serious. “Yields may be cut in half, if not more,” Jordan cautions.