Peanut farmers may need to include a peanut inoculant for the 2014 planting season. An unusually wet 2013 growing season followed by a cool, wet winter left peanut fields in the South potentially low in nitrogen-fixing microbes.

“I would highly recommend growers to strongly consider the investment in a peanut inoculant at planting this year, especially in poor draining fields that had standing water for more than a couple days.  When soils are saturated, oxygen is depleted and several things can occur with respect to these bacteria,” Scott Tubbs, cropping systems agronomist with the University of Georgia, is telling Georgia farmers and county Extension agents.

The amount of the native Bradyrhizobia in soil is likely much lower than in average years, he says, regardless of how many years it has been since the last time peanut or a cross-inoculating species was in a field.

Heavy rainfall shortly after a liquid inoculant was applied can leach or be diluted from the seed furrow, where it is needed. “Saturated conditions can also kill the bacteria leaving lower native populations for infecting future peanut plantings,” he said.

Most product labels say to apply 1 fluid ounce per 1,000 linear row feet, he says. But keep in mind this is for single-row. For twin-row, that amount would need to be doubled, hitting each of the twin furrows with the correct product amount.

“I have no data to support using a half-rate of inoculant per furrow to keep the total application rate per acre the same as a single row planting,” he said.

Tubbs provides more peanut inoculant ideas for 2014:

  • Do not confuse the granular inoculant formulation with the sterile peat/powder formulation, they are not the same.  The granular formulation, while also a dry product, is not applied to the seed prior to planting, it is metered through a dry metering box such as an insecticide/herbicide hopper and placed in-furrow.
  • Regardless of formulation, these are living organisms.  If you want them to remain alive and viable, don’t leave them sitting in the cab of a hot pickup truck or tractor, or exposed to direct sunlight.
  • Exposure to certain pesticides designed to kill living organisms, such insecticides or fungicides, may adversely affect the product.  Consult the labels or proper instructions for more information about mixing products.  There should be minimal concerns of exposure to typical peanut seed treatments, and short-term exposure to common in-furrow fungicides in the case of tank-mixes.  But a chlorine-free water source must be used as the carrier for liquid inoculants.
  • When soil conditions are relatively dry, liquid inoculants will disperse away from the intended target, thus the concentration of Bradyrhizobia near the seedling upon emergence and early season growth when infection should be occurring may be hindered.  The granular formulation will remain at the bottom of the seed furrow, where intended.  In non-irrigated conditions with only marginal soil moisture, granular products should be considered.

To get detailed information tailored for a particular farm, contact a local Extension agent.