Soybean Inoculation: Its Science, Use And Performance

The soybean is a legume who’s seeds generally contains 37% to 45% protein by weight. Depending on the protein content, a bushel of soybeans will cont ain between three and four pounds of nitrogen. The production of a 60-bushel per acre crop requires in excess of 300 pounds of nitrogen.

Some of the nitrogen comes from the oxidation of soil organic matter with the balance produced by bacteria residing in nodules on the plant’s roots. Each legume species requires different bacteria to fix nitrogen from the air and produce ammonium for use by the plant.

The Inoculation Process

The bacterial strain of Rhizobium used by soybean is Bradyrhizobium japonicum, and the process by which it gains access to the plant is very complex, but fairly well understood. Soybean plants release chemical signals (flavanoids) into the soil as they germinate and the plants emerge. These signals are picked up by the rhizobia in the soil and in inoculation material, and produce a return signal “Nod factor signal” to the plant. This return signal results in the plants’ roots preparing for infection by the bacteria.

The Nod factor signal causes the root hairs to curl, trapping rhizobia that are present on the surface of the root. An infection thread develops, and the rhizobia multiply until they reach the inside of the root. The cells of the root also begin to divide and form a specialized structure called a nodule. The rhizobia continue multiplying inside the nodules increasing their size. The enzyme (nitrogenase) that fixes nitrogen from the air to form ammonium cannot function in the presence of oxygen. In order for nitrogen fixation to occur, the plant must produce Leghaemoglobin in side the nodule to absorb oxygen in the root to prevent it from interfering with the nitrogen fixation process. Since Leghaemoglobin is red, the inside of an actively fixing nodule is pink. Sugars produced in the leaves travel to the root system and move into the nodules to provide energy that the rhizobium uses to extract nitrogen from the air to make the nitrogen compounds which the plant then uses to produce protein. The better this process works, the greater the grain yield and amount of protein produced.

Both plant and bacteria genes govern the entire nitrogen fixation cycle. Stresses on the bacteria or the plant such as cold, flooding, drought, and low soil pH can all interfere with this process. Cold temperatures delay the recognition of both the plant and bacteria signals. The plants and bacteria have to produce more signals in order to begin nodulation, which delays the onset of nitrogen fixation. Once enough signal is received and nodules develop, ammonium is produced and provided to the crop.

Drought reduces the moisture in the soil that protects the bacteria while it lives on the seed surface after planting. A dry seedbed and dry seed will quickly draw moisture from the inoculation material causing the bacteria on the surface of the seed to dry and die. If enough bacteria die, there will be little nodule formation and insufficient ammonium production for a good yield. Other stresses, including low soil pH, seed treatment chemicals, and starter fertilizers, can also kill the bacteria or inhibit nodulation. In fact, soil nitrogen levels in excess of 30-50 lbs per acre can stop both nodulation and nitrogen fixation altogether.

Click here to read Dr. Beuerlein’s full .pdf “Soybean Inoculation; Its Science, Use And Performance.”

SOURCE: Dr. Jim Beuerlein, The Ohio State University

Leave a Reply

Seed/Biotech Stories

Seed/BiotechSyngenta Delivers Two New Winter Wheat Varieties To Eastern Corn Belt
August 6, 2014
Adding to its portfolio of AgriPro brand wheat varieties, Syngenta introduces SY 007 and SY 474 soft red winter wheat varieties. Read More
Seed/BiotechWater Optimized Seed Flowing Freely
April 1, 2014
As the demand for ag to diminish its water use while maintaining high yields and crop quality increases, three companies are leading the movement to grow more with less water. Read More
Seed/BiotechBayer Applies For Seed Treatment That Protects Against Sudden Death Syndrome
February 26, 2014
If approved, ILeVO seed treatment would be the first product to provide breakthrough protection for soybean seedlings from the soil borne pathogen Fusarium virguliforme, the fungus that causes SDS. Read More
Seed/BiotechSeed Still Central
November 1, 2013
Advancing genetics continue to make seed the crop variable that calls the shots for the season. Read More

Trending Articles

ManagementExpert To Discuss Farmland Value, Rent At Farm Science Review
August 18, 2014
While cropland values in Ohio increased in the past two years, they have remained flat in 2014, declining in some cases, according to an Ohio State University agricultural economist. Read More
EquipmentAdvance Your Technology IQ At MAGIE
August 13, 2014
The Midwest AG Industries Exposition (August 20-21) is the place you need to be to see, study and evaluate how new advances in the equipment, operations, crop protection and fertility sectors can help your business prosper. Read More
HerbicidesScouting Key To Next Season’s Soybean Herbicide Program
August 12, 2014
When growing soybeans, growers need to think ahead to stay one step ahead of weeds. That means examining weed threats and evaluating which herbicides work best. Read More
StewardshipMichigan Agriculture Leaders On Toledo Water Ban: We Want To Be Part Of The Conversation
August 8, 2014
Leaders of Michigan agricultural organizations said Thursday that the government should not have a “knee-jerk reaction” based on last weekend’s water ban in Toledo due to fertilizer run-off in Lake Erie. Read More
CropLife 100BRANDT Acquires Lemon Ag Services
August 4, 2014
The acquisition of Lemon Ag fits BRANDT’s aggressive corporate strategy of providing superior agronomic advice and services for customers in central Illinois. Read More
Eric SfiligojThe Resurgence Of Crop Protection
August 4, 2014
Plenty of new offerings over the next few years should see a rebirth for the crop protection products category in terms of market share. Read More

Latest News

CropLife 100Pinnacle Acquires California-Based Retailer
August 29, 2014
Pinnacle Agriculture Holdings will acquire Kerman Ag Resources, Inc., which will operate under Pinnacle's Performance Agriculture brand. Read More
Allied Cooperative Grain Plant
ManagementArcadia Co-op To Merge With Allied Cooperative
August 28, 2014
Allied Cooperative has announced that members of Arcadia Co-op voted in favor of a merger with Allied Cooperative, paving the way for the consolidation which will be effective on December 1, 2014. Read More
InsecticidesBioinsecticide VENERATE Now Registered In California
August 27, 2014
Marrone Bio Innovations' VENERATE is a new tool to help California growers control crop-damaging insect pests, fight the development of insect resistance and reduce pesticide residues on fruits and vegetables. Read More
CropLife 100Two Iowa-Based Ag Co-ops To Merge
August 27, 2014
The Board of Directors and management of United Western Coop, Missouri Valley, IA has completed a merger with Heartland Co-op, West Des Moines, IA, effective September 1, 2014. Read More
FertilizerKoch Expands AGROTAIN Nitrogen Stabilizer Portfolio
August 26, 2014
Koch Agronomic Services, LLC has added two new innovative nitrogen stabilizers to the AGROTAIN product family – AGROTAIN ADVANCED and AGROTAIN DRI-­MAXX. Read More
Seed/BiotechDuPont To Build Two Seed Treatment Centers
August 26, 2014
DuPont has announced construction on two state-of-the-art centers dedicated to developing and testing seed treatment formulations, applications and seed handling techniques in an important step toward bringing new solutions to growers. Read More
Seed/BiotechLoveland Products Acquires A Controlling Interest In Ag…
August 26, 2014
Loveland Products, a subsidiary of Agrium , has announced the company has acquired a controlling interest in Agricen, a Dallas-area agricultural biotechnology company delivering biochemical-based products for efficient and sustainable plant nutrition. Read More
StewardshipUp Close Look At The 2014 Environmental Respect Award W…
August 25, 2014
The 2014 Environmental Respect Award winners were honored recently at the 24th annual event in Wilmington, DE. Read More
Eric SfiligojAg Science Rejection Carries Consequences
August 25, 2014
As innuendo and fear dog the regulatory process, agriculture can’t get the new tools it needs to combat world hunger. Read More
LegislationFarmers Dismayed As New Farm Bill Dumps Direct Payments
August 25, 2014
The threatened end of cash subsidies to the nation’s row crop farmers dates back through at least the last two iterations of national agriculture policy legislation. Read More
MAGIE 2014 ShowStopper
EquipmentJohn Deere Again Wins MAGIE ShowStopper Award
August 25, 2014
For the second consecutive year, John Deere was honored at the Midwest AG Industries Exposition (MAGIE) for its new R4045 sprayer. Read More
CropLife 100GROWMARK CEO To Retire
August 22, 2014
GROWMARK chief executive officer Jeff Solberg has announced his retirement effective September 15, 2014. Read More
InsecticidesDuPont’s Prevathon Approved For Dry Beans
August 22, 2014
DuPont Prevathon insect control powered by Rynaxypyr has received EPA registration for foliar use on dry bean crops, including dried shelled peas and beans. Read More
ManagementNCGA DuPont New Leaders Program Enters Sophmore Season
August 20, 2014
The National Corn Growers Association and DuPont are pleased to announce the second year of the NCGA DuPont New Leaders Program. Read More
FungicidesVerdesian Links Up With Mitsui, Hokusan
August 20, 2014
Mitsui Chemicals Agro, Inc., and Hokusan Co., announced the signing of an exclusive licensing agreement allowing Verdesian Life Sciences global access to its patented technology for suppressing mycotoxin contamination in wheat and barley. Read More
SprayersUniversity Of Illinois Introduces New Spray App
August 18, 2014
University of Illinois Extension has released a new smartphone app for making sprayer-related calculations. Pesticide Spray Calculator, or Spray Calc, Read More
Crop InputsSyngenta Names New Manager Of Federal Government Relati…
August 18, 2014
Laura Wood Peterson has joined Syngenta as manager of federal government relations, based in Washington, DC. Read More
ManagementExpert To Discuss Farmland Value, Rent At Farm Science …
August 18, 2014
While cropland values in Ohio increased in the past two years, they have remained flat in 2014, declining in some cases, according to an Ohio State University agricultural economist. Read More