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

Untreated soybean seed Heartland Coop
Seed/BiotechMarrone Bio Innovations, Groundwork BioAg Bio-stacked Microbial Seed Treatments Result In Increased Yields
February 13, 2017
Marrone Bio Innovations, Inc. and Groundwork BioAg, Ltd have announced successful seed treatment field trials of the world’s first all-biological Read More
Seed/BiotechNufarm Introduces New Seed Treatment Solutions
February 3, 2017
Nufarm Americas, Inc. has announced the addition of new, innovative and proven seed treatment solutions to its product portfolio. Promoting Read More
Seed/BiotechAgrisure Viptera Trait Demonstrates Effective Control Of Above-Ground Insects
February 1, 2017
Across the Corn Belt this past season, hybrids containing the Agrisure Viptera trait demonstrated effective control of above-ground insects in Read More
Syngenta plant
Seed/BiotechSyngenta AI Challenge To Address World Hunger With Machine Learning
January 31, 2017
Syngenta and the AI for Good Foundation have partnered to launch the Syngenta AI Challenge, a new international competition focused Read More
Trending Articles
Farmer and aptop
Matt Hopkins10 Warning Signs Your Website Is Grossly Outdated
February 8, 2017
Your Website is often a visitor’s first impression of your ag retail business. A positive first impression can set the Read More
AgriSync
Matt Hopkins17 Agriculture Apps That Will Help You Farm Smarter In 2017
December 9, 2016
Ag professionals are working smarter, not harder, than ever before. Smart farming technologies have enabled them to reduce costs, maximize Read More
R4023 Sprayer, John Deere
CropLife 100Ag Retail Equipment Report: The Green Party Continues
December 7, 2016
In the annual race for sales in the ag retail equipment marketplace, the color schemes for participants are a little Read More
Mike Stern
Precision AgClimate Corp. CEO Talks Retailer Support For Digital Ag
December 1, 2016
CropLife Magazine’s sister publication, AgriBusiness Global, recently sat down with Mike Stern, CEO of The Climate Corp., following the Monsanto subsidiary’s Read More
Precision AgTrimble Debuts End-to-End FMIS Platform
November 28, 2016
October’s inaugural PrecisionAg Vision Conference left this author with many thoughts and things to ponder in the coming months. Probably Read More
CHS Primeland
CropLife 100The 2016 CropLife 100 Report: Reviewing The Many Bulls And Bears Impacting This Year’s Marketplace
November 28, 2016
For virtually all of 2016, the nation was wholly focused on the big Presidential election. Some folks aligned themselves with Read More
Latest News
ManagementSouth Africa Update and the New New Leader G5
February 24, 2017
Editors Eric Sfiligoj and Dan Jacobs discuss the recent visit to South Africa by sister magazine AgriBusiness Global and the Read More
Fall Creek Watershed
StewardshipUpdate: Nutrient Stewardship In Indiana Requires Cool, …
February 24, 2017
Update: The application deadline for NCRS funding has been extended to March 17, 2017. Green leaves sparkle in the sunlight. Trees Read More
Greenleaf Technologies TADF03-D Dual Fan Nozzle
NozzlesSix Greenleaf Nozzles Approved For XtendiMax With Vapor…
February 22, 2017
Greenleaf Technologies has announced that six of its TurboDrop D Series nozzles have been approved for use with Monsanto’s XtendiMax Read More
Winter Wheat
Industry NewsTiger-Sul Hires Manitoba And Eastern Canada Account Man…
February 22, 2017
Tiger-Sul, a global leader in sulphur fertilizers and crop performance products, has announced that sales veteran Trevor Loewen has joined Read More
NFMS 17 Hagie Sprayer
Eric SfiligojThe Read From Louisville: Uncertain
February 22, 2017
By the time this column appears across the country, the annual Commodity Classic will be in full swing. This means Read More
SprayersApache 1000 Series Sprayer Earns 2017 EquipmentWatch Hi…
February 21, 2017
ET Works has been named a winner in the 2017 EquipmentWatch Highest Retained Value Awards program, the industry’s only award Read More
Measuring Bulk Tanks
StewardshipMeister Media Among 2017 Award Winners Presented By The…
February 21, 2017
The Pesticide Stewardship Alliance (TPSA) held its annual conference in San Diego, CA, earlier this month where three awards were Read More
John Reifsteck
CropLife 100GROWMARK’s Reifsteck Earns NCFC Director Of The Y…
February 21, 2017
GROWMARK Chairman of the Board and President John Reifsteck has earned the prestigious Director of the Year Award from the Read More
Roy Blunt
LegislationARA Recognizes Blunt, Heitkamp For Legislative Efforts …
February 17, 2017
Agricultural industry continues to face federal regulatory challenges. Thankfully, agriculture’s allies in the U.S. Senate stepped forward. The Agricultural Retailers Read More
LegislationThe Fertilizer Institute Commends Senate On Confirmatio…
February 17, 2017
The Fertilizer Institute (TFI) President Chris Jahn issued the following statement on the Senate confirmation of Oklahoma Attorney General Scott Read More
Trump, Senate, Cabinet
LegislationBREAKING: Trump EPA Nominee Scott Pruitt Confirmed by S…
February 17, 2017
Scott Pruitt, who as Oklahoma’s attorney general spent years suing the Environmental Protection Agency over its efforts to regulate various Read More
ManagementFebruary Road Trip Edition
February 17, 2017
Editors Paul Schrimpf and Eric Sfiligoj discuss their recent visits to Indiana and Kentucky. Read More
Heritage Cooperative Finished Building Aerial
ManagementHeritage Cooperative, Agland Co-op Approve Merger
February 17, 2017
Agland Co-op and Heritage Cooperative stockholders have both approved the merger agreement between Agland Co-op and Heritage Cooperative. Now begins Read More
LegislationARA Fly-In: Ag Retail Descends on Capitol Hill, Lawmake…
February 15, 2017
More than 100 agricultural retailers, distributors and suppliers headed to Capitol Hill Tuesday morning for the Agribusiness Congressional Fly-in, according to a Read More
Untreated soybean seed Heartland Coop
Seed/BiotechMarrone Bio Innovations, Groundwork BioAg Bio-stacked M…
February 13, 2017
Marrone Bio Innovations, Inc. and Groundwork BioAg, Ltd have announced successful seed treatment field trials of the world’s first all-biological Read More
NL5000 With G5 Technology
SpreadersNew Leader Introduces NL5000 Dry Nutrient Applicator Wi…
February 13, 2017
New Leader, a division of Highway Equipment Company (HECO), has announced the next generation of spreading technology with the NL5000 Read More
Fertilizer Storage
Crop InputsThe State Of The Fertilizer Industry
February 9, 2017
He’s all hat, no horse.” It’s a humorous way of describing a person who tells a good story, but is Read More
CropLife 100Pinnacle Agriculture Agrees To Credit Agreement Amendme…
February 9, 2017
Pinnacle Operating Corp. has entered into an amendment (the “Amendment”) to its First Lien Credit Agreement that will provide for, Read More