Understanding Inoculation Techniques For Legumes

Inoculum is not magic dust — it contains bacteria that must be kept alive. According to Penn State Extension, all packages of inoculum have an expiration date. After this date, the bacteria may not be alive and the inoculum should not be bought or used. Heat and direct sunlight kill bacteria in stored inoculum, even while packaged. Since a short period of heat can reduce the number of live Rhizobia, the package should be kept in a cool place and out of direct sunlight — even when taking it home from the store (keep it off the dashboard). The preferred storage place for inoculum is the refrigerator (do not freeze).

Live bacteria may be added to the soil (direct-soil application) or to the seed (seed-applied inoculant).

Direct-soil Application

Granular forms of inoculum may be placed in the seed row via the insecticide box of a planter or through the fertilizer or grass seed box of a drill. (Clean the box before inoculum is placed in it.) The granules flow freely through field planting equipment, and their flow should be calibrated and metered.

Frozen or concentrated liquid cultures of inoculant may be diluted to a slurry, then added to a water-filled tank for spray application into the seed row.

Inoculant should not be mixed with either pesticide or fertilizer if applied to the seed row. When seeding forage legumes, it is recommended that fertilizer be applied separately.

Application of inoculant directly to the soil has been quite effective. However, the greater surface area being covered by the inoculant required more of the material. This is especially the case when narrow-row soybean planting is practiced. Therefore, the method is more expensive than seed inoculation.

Seed-applied Inoculant

Inoculum to be mixed with seed before planting is available on a variety of carriers; the most common carrier is peat. Peat has proven to be better than most other carriers in preserving live bacteria under unfavorable conditions (high temperature, late planting).

Inoculating seed
When inoculating seed, two conditions must be satisfied to get good nodulation:

  1. The roots must be in contact with the Rhizobia bacteria, and
  2. The Rhizobia must be alive and able to infect the plant root.

For the bacteria to be in contact with the roots of every plant, inoculum should cover each seed. To achieve the best distribution, the inoculum should be mixed with seed in a large space rather than in a planter seedbox—on a tarp-covered floor, in a tub, in a cement mixer (paddles removed), or in the bed of a pickup.

Using an adhesive (also known as a sticker) helps the inoculant to adhere to each seed. This is especially important with small-seeded forage legumes, which need more inoculant per unit of seed-surface area. Both commercial and homemade stickers are effective. A homemade sticker can be prepared as a 1-in-10 dilution of syrup or molasses, diluted cola or milk also can be used.

Mix seed with enough sticker to just moisten all seeds. Too much liquid may cause premature germination of the seed. To the moistened seed add inoculant and mix to coat the seeds. Air dry by spreading the coated seed in the shade. Drying may be speeded by adding additional peat-based inoculant or finely ground limestone. The seed must be dry to flow properly through the planter. Calibrate the seeder with inoculated seed when setting desired seeding rate. Seed should be planted as soon as possible after inoculation because bacteria begin to die in the drying process. If not planted within 24 hours, reinoculate.

The rate of inoculant to use depends on the amount of time elapsed since the legume was last grown in that field and on the conditions for bacteria survival at the time of planting. Start with the manufacturer’s recommendations. If the soil is dry and germination of the seed is expected to be delayed, then a higher rate of inoculant is required to make up for loss of some Rhizobia. For soybeans being planted into a new field, three times the normal rate of inoculant is recommended. A good way to achieve this is to moisten the seed with liquid inoculant applied at the normal rate, then mix seed with twice the normal rate of peat-based inoculant.

Preinoculated Seed

Forage seed may be purchased already inoculated. One of two methods of preinoculation is generally used: (1) impregnation with Rhizobia by a vacuum process or (2) pelleting with fine limestone. The pelleted type of preinoculated seed is generally preferred on the basis of research that shows that bacteria live longer on the pelleted seed and that this type of preinoculated seed results in formation of a greater number of root nodules.

Preinoculated seed should be handled in the same way as packaged inoculum. Several precautions can ensure better results. Check for an expiration date on the seed-bag tag, store and transport the seed out of direct sunlight and heat, and plant the seed as soon as possible. If you believe that bacteria may have died, then reinoculate the seed. Since water or the sticking solution causes the lime content of pelleted seed to gum up, use mineral oil (0.5 to 1.0 of oil per lb of seed) to adhere new inoculum to seed. Plant immediately.

Read the full story on the Penn State Extension website.

Leave a Reply

Seed/Biotech Stories

Bayer
Crop InputsBayer to Sell Liberty Business to Seal Monsanto Deal
May 8, 2017
Bayer has agreed to sell its Liberty herbicide and LibertyLink-branded seeds businesses to win antitrust approval for its acquisition of Read More
Crop InputsEPA OKs Monsanto NemaStrike Technology in Row Crops
May 2, 2017
Monsanto Co. announced that the U.S. EPA issued registration for tioxazafen, which is branded as NemaStrike Technology. This approval will Read More
Syngenta headquarters in Basel, Switzerland
Crop InputsFortune: Inside China’s $43 Billion Bid for Food Security
April 26, 2017
(Via Fortune.com) The worst famine in human history occurred in China from 1959 to 1961. An estimated 34 million people Read More
BPIA logo
Seed/BiotechBPIA Files Comments with USDA
April 24, 2017
The Biological Products Industry Alliance (BPIA) has filed comments with the USDA’s Animal and Plant Health Inspection Service (APHIS) Plant Read More
Trending Articles
Migrant farm workers
LegislationTrump: Immigration Crackdown Won’t Impact U.S. Agriculture
May 16, 2017
President Donald Trump said he would seek to keep his tough immigration enforcement policies from harming the U.S. farm industry Read More
AGCO Ratliff featured
Eric SfiligojRemembering Robert Ratliff
May 15, 2017
With all the fast-paced happenings in agriculture this spring, with multiple mergers in the works and planting season in full Read More
Case sprayer nozzle closeup
EquipmentSpray Application: A Nozzle Renaissance
May 2, 2017
If you had asked four-decade ag veteran Mark Bartel, President of Wilger Inc., just a few years ago what lay Read More
ManagementWashington Update, Dow-DuPont Earnings, and the Passing of an AGCO Legend
April 27, 2017
Editors Paul Schrimpf and Eric Sfiligoj talk about the latest Beltway news, crop protection company 1st quarter numbers, and the Read More
Crop InputsFlying Under the Radar No More, FMC Goes Big
April 13, 2017
Describing FMC as “under the radar,” admittedly, is probably a stretch. But in a snap of the fingers, FMC upped Read More
Young Corn Plants
Crop NutritionStill Hunting Yields
April 1, 2017
There’s no denying it — the agricultural marketplace today is undergoing a fundamental shift in fortunes. Not too many years Read More
Latest News
FungicidesSyngenta Launches New Seed Treatment Fungicide
May 22, 2017
Syngenta has announced the launch of PLENARIS seed treatment fungicide for the control of downy mildew in sunflower. PLENARIS contains Read More
Corn close up
Crop InputsMonsanto’s First HPPD Herbicide Garners EPA Appro…
May 19, 2017
Monsanto announced today that EPA has federally approved Harness MAX Herbicide, the first herbicide in the Monsanto portfolio to provide Read More
ManagementPrecision Planting Deal, China Developments, and Enviro…
May 18, 2017
Editors Eric Sfiligoj and Dan Jacobs discuss the latest news on John Deere’s now dead deal for Precision Planting, China’s Read More
Soybean aphid leaf
InsecticidesMulti-state Research Reveals IPM Best Option for Treatm…
May 17, 2017
About 89.5 million acres of soybeans will be planted across the U.S. in 2017 — a record high, according to Read More
GROWMARK-2017-Interns
CropLife 100GROWMARK Names 2017 Summer Interns
May 16, 2017
Forty-two college students are exploring agricultural career opportunities this summer as GROWMARK interns. They are working at FS member cooperatives Read More
Migrant farm workers
LegislationTrump: Immigration Crackdown Won’t Impact U.S. Ag…
May 16, 2017
President Donald Trump said he would seek to keep his tough immigration enforcement policies from harming the U.S. farm industry Read More
Flooded corn in Indiana
FertilizerBoth Wet and Dry Conditions Threaten Nitrogen Loss
May 15, 2017
The weather is notoriously unpredictable, leading to challenges for planting, harvesting and applying the nitrogen (N) your corn crop needs. Read More
farmer Kip Tom
Precision AgAg Tech: On the Cusp of Something Big?
May 15, 2017
The investment and ag-tech sectors’ continuing courtship of agriculture, smoldering for three or four years now, was well in evidence at Read More
AGCO Ratliff featured
Eric SfiligojRemembering Robert Ratliff
May 15, 2017
With all the fast-paced happenings in agriculture this spring, with multiple mergers in the works and planting season in full Read More
Greg Musson, Gar Tootelian
ManagementOpinion: Shaking Your Perspective in Ag Retail
May 12, 2017
Some of you I’m sure have encountered our recently retired salesman extraordinaire, Dan Bellanger. He worked in the industry for Read More
Exterior view of CPS Big Lake facility which includes enclosed receiving and load out area
CropLife 100New Alternative Weed Resistance Traits Could Experience…
May 12, 2017
It wasn’t too many years ago that ag retailers and their grower-customers could hardly wait for new options to fight Read More
Diane Allemang and Dan Jacobs
Crop InputsFMC Agricultural Solutions, Casa Pacifica Partner to He…
May 11, 2017
FMC Agricultural Solutions is teaming up with Casa Pacifica Centers for Children and Families, an organization that supports vulnerable children Read More
UncategorizedWhat’s Up With ARA
May 11, 2017
CropLife Editor Eric Sfiligoj talks with Brian Reuwee regarding what issues are on the docket for the Agricultural Retailers Association. Read More
BASF Maglis tablet retailer grower
Precision AgQ&A: What BASF’s Latest Foray into Precision …
May 11, 2017
In late April, BASF agreed to acquire U.S. precision ag player ZedX, a leader in the development of agronomic weather, Read More
Pam Marrone
Crop InputsMarrone Bio Innovations Enters into Distribution Agreem…
May 11, 2017
Marrone Bio Innovations, Inc., a leading global provider of bio-based pest management and plant health products for the agriculture markets, Read More
Bayer
Crop InputsBayer to Sell Liberty Business to Seal Monsanto Deal
May 8, 2017
Bayer has agreed to sell its Liberty herbicide and LibertyLink-branded seeds businesses to win antitrust approval for its acquisition of Read More
Trump, Senate, Cabinet
LegislationTrump’s EPA Appointee Dismisses Half of Major Sci…
May 8, 2017
(Via NYTimes.com) EPA has dismissed at least five members of a major scientific review board, the latest signal of what Read More
Winter Wheat
FungicidesREGALIA Rx Available from Koch Agronomic Services for 2…
May 8, 2017
Koch Agronomic Services, LLC has announced that REGALIA Rx biofungicide is available for U.S. corn, wheat and soybean growers who Read More