Liquid inoculants important for peanuts grown in new fields

In new land peanut production it is critical to add liquid inoculants to insure adequate nitrogen in the soil for optimum peanut production. When to use nitrogen-fixing inoculants and what type are key management decisions for peanut producers.

The end of the peanut allotment program in the 2002 farm bill created dramatic shifts in where peanuts are grown in the United States. In the upper South, the end of the tobacco program, created more new opportunities for peanuts on land that traditionally produced tobacco.

On new land, or land that has been out of peanuts for more than three years, use of liquid inoculants is critical to optimum yields and quality. On new land peanuts, it is common to see yield increases of 1,500 pounds per acre using in-row liquid inoculants.

Whether inoculants pay on land in which peanuts have been in a two- or three-year rotation with corn or cotton depends on the yield potential of the land, according to Jay Chapin, South Carolina peanut specialist.

“In South Carolina in 2006 we will still have a lot of land that has never had a peanut on it. Tests in 2005 on land that has never had peanuts showed 1,000 pounds per acre yield boost on land with good residual nitrogen using liquid inoculants,” he notes. On land without good residual nitrogen, up to 1,500 pounds of peanuts per acre more than check plots were common.

Though there is little difference among the liquid inoculants used in the South Carolina tests, Chapin notes that liquid inoculants consistently provided 1,000 pounds per acre yield increase over check plots, compared to 500 pounds per acre yield increase using granular inoculants.

“We really didn't see much difference in nodule counts from the different liquid inoculants in our tests, but the difference between any of the liquid products and any of the granular products was dramatic,” Chapin emphasizes.

Cheaper is not always better, Chapin says, in selecting which inoculant to use. “In these times price is always important, but if you have had good results from an inoculant and good service from the company that sells it, my advice is to stick with them,” Chapin notes.

The South Carolina specialist says to avoid using chlorinated water and be sure application equipment is working properly. Unless there is a good reason to tank-mix something with the inoculant — don't do it.

For growers who started with peanuts in 2003 and are coming back to peanuts after two-year rotations, it is a new world when considering using inoculants. “If you are coming back to peanuts after two years out, you will not see the same yellowing from nitrogen deficiency that is so evident on first year peanuts,” Chapin stresses.

Whether using inoculants on rotated land is cost efficient is highly dependent on the land. On land capable of producing high yields, 300 to 400 pounds per acre increases every third or fourth year, may be economically sound — it depends a lot on the operation, Chapin notes.

The Clemson scientist reminds peanut producers that inoculants are living organisms and providing an optimum environment for the bacteria to live and do their work is critical to the success of the product.

The increased yield from nitrogen-fixing inoculants comes from a variety of sources. Earlier nodulation, more uniform stand and vigor of plants are factors that have been proven in tests across the peanut producing belts.

On peanut land without adequate nitrogen-fixing bacteria, seed are planted and seedlings develop. Over a period of time, the plant develops a physiological need for nitrogen, recognizes nitrogen-fixing organisms in the soil, and after active molecules become available and absorbed by the plant, seedlings emerge from the soil to create a stand.

On peanut land deficient of nitrogen-fixing microbes but inoculated with these organisms, the peanut plant skips these multiple steps, absorbs available nitrogen molecules and seedling emerge. Similar steps are skipped in vegetative growth and fruiting on land with adequate nitrogen fixation.

Sidney Fox of Nitragin Incorporated says additional benefits of using an inoculant come at harvest. “Hull scrape tests in Georgia and Texas showed that peanuts treated with Optimize Lift matured several days earlier than untreated peanuts. This means that peanuts can be dug earlier, providing growers a good harvest management tool, especially if they grow multiple crops with similar harvest windows.”

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