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

Pam Marrone
Crop InputsQ&A With Pam Marrone On The World’s First All-Biological Seed Treatment
April 4, 2017
Marrone Bio Innovations Inc. and Israel-based Ground­work BioAg in February announced successful field trials of the world’s first all-biological comprehensive Read More
Soybean Field
Seed/BiotechBayer Invests $8.1 million In Soybean Advancement In The Midwest
March 16, 2017
Growers in Illinois and across the Midwest now have the added benefit of a state-of-the-art soybean research facility, increasing accessibility Read More
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
Trending Articles
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
Nutrients for Life Foundation Teacher
FertilizerNutrients For Life Foundation Celebrates 10 Years Teaching Fertilizer Education
March 23, 2017
Those in agriculture know fertilizer is a vital ingredient to grow strong, productive crops. In fact, fertilizer is responsible for Read More
AdjuvantsA New Weed-Control Era Begins: But First, One Last Obstacle
March 4, 2017
There is trepidation, there is reluctance, and there is excitement. Ag retailers feel it all about the new dicamba and Read More
LIFT Academy video screenshot
Crop InputsLIFT Agriculture Academy: A Q&A With West Central Distribution’s Dean Hendrickson
March 1, 2017
West Central Distribution recently launched its LIFT Agriculture Academy, a new, premiere training and professional development resource for West Central’s ag Read More
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
Latest News
ManagementAn Inside Look at Award Winning Ag Retailer Gar Tooteli…
April 20, 2017
CropLife Editor Eric Sfiligoj discusses An Inside Look at Award Winning Ag Retailer Gar Tootelian Read More
Students Soybean Field
Industry NewsMACA Announces 2017 Young Leader Scholarship Recipients
April 19, 2017
The Mid America CropLife Association (MACA) Board of Directors selected 11 college students to receive the MACA Young Leader Scholarship Read More
Growmark FS Outlet
SoftwareKnoa Software Solution Helps GROWMARK Boost System Perf…
April 19, 2017
Knoa Software, a leading provider of user experience management (UEM) software, has announced that GROWMARK, Inc., a regional agricultural cooperative Read More
Crop InputsFBN Publishes ‘Voice of the Farmer’ Agricul…
April 17, 2017
Farmer’s Business Network (FBN) released today its “The Voice of the Farmer”, which the company is describing as “a special Read More
ManagementTalking Responsible Ag
April 13, 2017
CropLife Editor Eric Sfiligoj discusses the Responsible Ag program with director Bill Qualls. 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
Crop InputsWhat do Roundup and Mickey Mouse Have in Common? Califo…
April 13, 2017
(SOURCE: East Valley Times) Glyphosate, the active ingredient in Monsanto Co.’s Roundup and many other weed killers, is being added Read More
Syngenta headquarters in Basel, Switzerland
Crop InputsSource: ChemChina to Divest Assets to Adama Following S…
April 11, 2017
China National Chemical Corp. plans to redistribute agrochemical assets to its Adama unit after the $43 billion takeover of Syngenta Read More
Farming drone air
Eric SfiligojThe Interest in UAVs for Agriculture Grows
April 10, 2017
At times, it seems as if experts have been predicting “big things” for unmanned aerial vehicles (UAVs) for several years Read More
OpinionOpinion: Taking On The Farmers Business Network
April 8, 2017
Well, another round of venture capital funding has come to Farmers Business Network (FBN), followed up with the obligatory feature Read More
Drone
EquipmentFarming Drones: The Future Of Agriculture?
April 7, 2017
Chances are, you already know drones are amazing. After all, this is something DroneLife readers just understand. But if you’re Read More
ManagementFMC-DuPont, Crop Plantings, and UAV Updates
April 6, 2017
Editors Eric Sfiligoj and Jackie Pucci discuss the purchase agreement between DuPont and FMC, the 2017 crop acreage mix and Read More
Falcon soil sampler
EquipmentSerious Soil Sampling Rigs
April 6, 2017
The industry has seen an increase in automation in sampling equipment, and consultants now often pull cores with an automated Read More
Iowa waterways
FertilizerDow AgroSciences Recognizes Ag Retailers’ Role in Prote…
April 6, 2017
The state of Iowa and its agriculture community have worked for decades to preserve soil health, protect water quality and Read More
Farmer Scouting Weeds in Soybean Field
EquipmentSoil, Scouting Programs Continue To Gain Value
April 5, 2017
How much growers and their retailers utilize soil testing and scouting varies greatly. But they should step up their game Read More
Forbes Mixing Bowl NYC
Precision Ag6 Key Takeaways from Forbes Mixing Bowl NYC
April 5, 2017
Advisory investment group The Mixing Bowl teamed up with Forbes for its New York-based event this year to discuss technology’s Read More
Pam Marrone
Crop InputsQ&A With Pam Marrone On The World’s First All-Biolo…
April 4, 2017
Marrone Bio Innovations Inc. and Israel-based Ground­work BioAg in February announced successful field trials of the world’s first all-biological comprehensive Read More
Corn soil
Crop NutritionBiostimulants Clamor For A Piece Of The Row Crop Market
April 3, 2017
The question these days isn’t who is venturing into biostimulants — it’s who isn’t. Or more to the point: The Read More