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/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
Seed/BiotechBayer CropScience, Northstar Agri Industries Launch New Canola Hybrid
October 16, 2013
Northstar Agri Industries and Bayer CropScience have announced the addition of the InVigor L252 hybrid to the Northstar Star Growers High Oil Contract. Read More

Trending Articles

EquipmentSummer Show Preview 2014: Superior Sprayers Take The Field
July 3, 2014
In this final installment of our coverage of the major categories of Big IRON that retailers can expect to test-drive at this summer’s events, here is a look at 19 sprayers. Read More
Scouting a soybean patch at Green Valley Ag.
EmployeesCropLife Compensation Survey: Battling Talent Drain
July 2, 2014
Retailers too often lose employees to companies outside of agriculture, while recruiting efforts are most often limited to competitors and other ag-focused organizations. Read More
HerbicidesDow AgroSciences Introduces SureStart II Herbicide
June 16, 2014
The enhanced formulation has improved viscosity and increased stability under heat and controls more than 60 high-anxiety grasses and broadleaf weeds found in corn fields. Read More
HerbicidesBASF Investing $270 Million To Expand U.S. Herbicide Production
June 11, 2014
BASF has invested more than $270 million to expand herbicide production capacities in the U.S., including more than 20 new products to be launched over next two years. Read More
EquipmentGPS: 25 Years And Still Growing
June 2, 2014
The evolution of global positioning systems applications in agriculture remains ongoing as the technology hits a notable milestone. Read More
CropLife 10013 Key Acquisitions Pinnacle Has Made In The First Half Of 2014
May 29, 2014
The only thing that has reached a more frenzied pace than #plant14 might be the multiple acquisitions that Pinnacle Agriculture Holdings has made in the first half of the year. Read More

Latest News

Soybean Field
InsecticidesTranform WG, Closer SC Insecticides Receive R&D 100…
July 23, 2014
Dow AgroSciences has received the award from R&D Magazine for Transform WG insecticide and Closer SC insecticide with Isoclast active. Read More
EquipmentKinze, Raven Team Up On 4900 Planter Monitor
July 23, 2014
Kinze Manufacturing announces a partnership with Raven Industries to develop a standalone monitor solution for the Kinze 4900 series planter. With this new Read More
LegislationNew Farm Bill Continues To Confuse As Growers Await USD…
July 23, 2014
The new five-year Farm Bill eliminates many of the direct payments previously payed to growers and could benefit from USDA clarification, reports a Toledo Blade columnist. Read More
EquipmentPrecisionAg.com Relaunches With Responsive Design For M…
July 22, 2014
PrecisionAg, the worldwide leader in precision agriculture information and analysis, announces the launch of its completely redesigned website, PrecisionAg.com. Read More
FungicidesEPA OKs Two Willowood Fungicides
July 21, 2014
The EPA has approved Willowood Azoxy 2SC and Willowood AzoxyProp Xtra. two widely used broad spectrum, preventative fungicides with systemic and curative properties. Read More
Precision AgFarmers Learning Fast As UAVs Take Off
July 17, 2014
Farmers and others interested in how UAVs can be used in agricultural applications were able to learn more about the technology during the recent Precision Aerial Ag Show. Read More
CropLife 100Bobby Knight, Richard Petty To Highlight Ag PhD Field D…
July 17, 2014
Attendees at the July 24 Ag PhD Field Day at Hefty Farms will learn about the latest agricultural technologies, and get a chance to meet legendary sports figures Bobby Knight and Richard Petty. Read More
WebinarsUpcoming Webinars
July 17, 2014
Register for one of our upcoming Webinars or access our archive of past Webinars to view recordings of presentations that may be of interest to you. Read More
A finished Willmar 16-ton side-shooting tender.
TendersNew Production Facility Helps Willmar
July 17, 2014
In 1963, a group of businessmen started Willmar. Today, a half-century later, the company is one of the ag industry’s longest-running brands. Read More
FertilizerCF Industries Sells Carbon Credits To Chevrolet, Donate…
July 17, 2014
CF Industries has completed the sale of a large block of carbon reduction credits to Chevrolet, and will donate the net proceeds of $600,000 to the National FFA Foundation. Read More
CropLife 100Grainland Cooperative, Minier Cooperative Grain To Merg…
July 17, 2014
The shareholders of Grainland Cooperative and Minier Cooperative Grain Co. approved a merger of company operations effective August 1, 2014. Read More
ManagementStudy: Drought Costing California Billions
July 17, 2014
A new study has found the drought has cost the state $2.2 billion, primarily in lost farm revenue and wages. Read More
FertilizerCF Industries Resumes Production At Oklahoma Nitrogen C…
July 17, 2014
The company had shut down production at the Woodward, OK, facility in April to address an issue in one of the site’s boilers. Read More
CropLife 100Wilbur-Ellis To Relocate Agribusiness Division To Denve…
July 16, 2014
The move Eastward will allow Wilbur-Ellis’ Agribusiness Division to be more accessible to relevant geographies and is expected to enhance communication and collaboration among the division’s nearly 3,000 employees. Read More
Soybean field
FungicidesValent Launches New Seed Protection Fungicide For Soybe…
July 16, 2014
The INTEGO SUITE System contains the first new, novel seed protection fungicide chemistry registered in 30 years by the EPA for protection against Pythium and Phytophthora. Read More
Crop InputsSyngenta Drive To Thrive 10 Finalists Announced
July 15, 2014
Finalists are chosen based on the quality of their essays and photos depicting what makes them thrive. Read More
FertilizerHow To Minimize Phosphorus Losses In Runoff
July 15, 2014
Phosphorus losses from agricultural fields can be divided into three categories: flash losses of soluble phosphorus, slow leak losses and erosion events. Here's how to minimize losses in each instance. Read More
ManagementCalifornia Drought Threatens To Dry Up Farm Wells
July 15, 2014
Farmers hit hardest by California's drought could begin to see wells run dry next year, according to a new study by The Center for Watershed Sciences at the University of California, Davis. Read More