Rhizobial Inoculants: a Consistently Profitable Input in Legume Crops

By Becker Underwood

In today’s challenging environment, farmers are continually seeking ways to maximize their yield potential and return on investment. Rhizobial inoculants, that help legume plants extract nitrogen from the air and convert it into a form they can use, represent a sound management practice for achieving these objectives.

Inoculation is the process of applying commercially available rhizobial bacteria to legume seed or into the soil where legume crops – soybeans, peanuts, alfalfa, peas and lentils – will be planted. Rhizobia are the active ingredient in all legume inoculant products. The presence of rhizobia is necessary for a legume to be able to convert atmospheric nitrogen into a usable form in the absence of readily available nitrogen from fertilizers or manure. This process is referred to as nitrogen fixation.

Farmers can realize multiple benefits in using nitrogen-fixing rhizobia, including improved crop performance, reduced production costs and reduced greenhouse emissions associated with the production of synthetic nitrogen fertilizers.

Higher yields, strong ROI

Legume crops, when properly inoculated, consistently produce higher yields that generate greater income for growers. In peanuts, for instance, the use of VAULT® liquid inoculant from Becker Underwood has increased yields anywhere from 200 to 1,500 pounds per acre.
University and field trials have shown fresh VAULT inoculants increase yields in soybeans an additional 2 to 2.5 bushels per acre. When you consider an inoculant treatment typically costs around $3 to $4 per acre, a two-bushel yield increase generates a handsome return on investment of at least 4-to-1 in soybeans marketed at $8 a bushel.

Jim Beuerlein, professor of agronomy and soybean research and extension specialist for The Ohio State University, has evaluated soybean inoculants in hundreds of field trials over the past 15 years. Those trials have shown that inoculation generates an average yield increase of nearly 2 bushels per acre.

“Our evaluations have shown that over time inoculants deliver a 300 to 500% return on investment, and they do this over a wide range of soil types and production systems. To me, inoculants are one of the most consistently profitable inputs growers can use in their operations,” Beuerlein says. “Oftentimes inoculants are dismissed because a two-bushel increase over a 50- to 60-bushel yield isn’t considered to be statistically significant. But that two-bushel increase – generated with a nominal investment – is very economically significant. The fact is inoculation does work, and it has proven itself to be very profitable in the real world.”

Rhizobial inoculants are also seen as low-cost insurance for maximizing yields in peanuts. David Jordan, peanut agronomist at North Carolina State University, has overseen extensive field trials on inoculants in his state. His take: “Inoculants should be routinely applied each time peanuts are planted. In fact, the cost of inoculant is 1% or less of the total peanut budget, which makes it an input that needs to be included in all cases.”

Nitrogen credit, fertilizer savings

The air we breathe is 79% nitrogen. Legume crops, inoculated with fresh rhizobia, have the unique ability to convert this “free” atmospheric nitrogen into ammonia and ultimately amino acids that fuel the healthy growth of legume plants. These legume crops, then, make a significant contribution to the corn or small grain crops that are planted into these same fields the next growing season. Soybeans, for example, deliver a nitrogen credit that can range from 55 to 120 pounds. This credit enables growers to reduce their investment in synthetic nitrogen fertilizers, which helps lower their total production costs for that following crop.

Planting inoculated legumes also delivers a significant environmental benefit. The production of synthetic nitrogen fertilizers generates large volumes of carbon emissions. Reducing the need for synthetic nitrogen fertilizers decreases greenhouse gas emissions. And by applying less nitrogen to their fields, growers lower the risk of nitrogen leaching into the groundwater.
A final consideration for keeping legumes in a regular rotation is that these plants tend to decompose rapidly, leaving organic matter in the soil, thus improving its physical, chemical and biological condition.

When should you inoculate?

When it comes to producing legumes the question many growers have is “When should I inoculate?” While the short answer is every year, several factors are combining to make 2009 a particularly compelling year for growers to consider incorporating inoculants into their production regimens.

• Many industry analysts are predicting record soybean plantings approaching 80 million acres in the U.S. in 2009. Many of these soybeans will be planted into either CRP acres or fields that have been in continuous corn for several years. In either instance, these soils typically have depleted rhizobia populations.
• In 2008, many millions of acres of cropland throughout the upper Midwest experienced flooding. Flooding results in anaerobic conditions in the soil that can kill native rhizobia. A rhizobial inoculant will be critical for proper nodulation in legumes planted into these soils in 2009.
• While rhizobia can stay in the soil for some time, there is no way to effectively test to determine if the rhizobia in the soil are specific to the legume crop being planted, and if they are in sufficient quantities to effectively nodulate the crop.
• Native rhizobia have a tendency to become less vigorous, or lazy, over time. Applying an inoculant, such as Becker Underwood’s VAULT inoculants for soybeans and peanuts, helps ensure that fresh, vigorous rhizobia are present and ready to move into the roots to multiply, nodulate and begin fixing nitrogen.
• While native rhizobia have proven survivability, there’s no doubt that commercial inoculants contain the most effective strains in terms of nitrogen fixation.

Selection considerations

When growers are pondering the selection of an inoculant for their legume crop, the first factor they should consider is the reputation and credibility of the company they want to do business with. Becker Underwood is the global leader in inoculant production and sales. The company also is the leading supplier of rhizobial inoculants in Canada. This is significant because, unlike the U.S., the Canadian market is highly regulated, with the government mandating proof of performance. Some popular U.S. products have been unable to gain Canadian approval. Becker Underwood also places a heavy emphasis on independent field trials in all the key market segments, including soybeans, peanuts and peas and lentils. Second, remember that the fresher your inoculant, the better the performance. Rhizobia are living organisms. Inoculants are only effective if these organisms are alive and available in the proper quantities to allow legume crops to form beneficial root nodules. At Becker Underwood, we make our VAULT inoculants for the U.S. soybean and peanut markets fresh every year for that specific growing season. This helps ensure delivery of the strongest, most vigorous rhizobia possible for maximum nitrogen fixation and greatest potential yield benefit in these important legume crops.

Advances in Inoculant Technology

Through research and selection, today’s inoculant technology represents significant advancement, even when compared to only 5 or 10 years ago. As the technology has advanced, inoculants suppliers have consistently increased their ability to deliver significantly higher levels of live, beneficial bacteria to each seed. Ease of use also has improved significantly in recent years. 

The industry has largely moved from non-sterile, powdered peat products to sterile peat formulations with greatly increased rhizobia numbers. Liquid products with even higher numbers of active rhizobia have been introduced. And now, in the most recent evolution, Becker Underwood is delivering BioStacked® inoculants that combine multiple performance-enhancing biological organisms that boost nitrogen fixation while also helping inoculated plants produce a more robust root system with greater nodule biomass. And, of course, a healthier root structure is key to accessing the critical moisture and nutrients soybean plants need to produce top yields.

What does the future hold? Inoculants are evolving to include both nitrogen-fixing rhizobia as well as other naturally-occurring, beneficial biological organisms and agents that can act as bio-fungicides, bio-insecticides, growth enhancers or serve in other performance-enhancing roles.

A Market Leader

Becker Underwood has provided superior seed enhancement products, including colorants and polymers, for more than two decades. Today, the company ranks as the global leader in the production and sales of inoculants for legume crops. In addition, Becker Underwood is the global leader in beneficial nematode development and sales. The company also is rapidly gaining a reputation for its role in identifying and developing a new-generation of inoculant products for leguminous and non-leguminous crops that might best be described as biological crop performance enhancers.

Becker Underwood divisional offices and production facilities are located in Australia, France, Brazil, Argentina, Canada and the United States, in addition to the corporate headquarters in Ames, Iowa.

As the industry leader, the company remains committed to the global inoculant market and to continuous advancement of the technology.  This commitment is evident in the recently completed expansion of our U.S. production facility in St. Joseph, Missouri. This major project, which tripled production capacity for the 2009 growing season compared to 2008, will enable Becker Underwood to support the anticipated, continued growth in demand for our biological products and help meet the expanding needs of the marketplace.

For more information on the use and benefit of rhizobium inoculants, please visit www.beckerunderwood.com.
 
Becker Underwood inoculant products (U.S. Market)

Soybeans:

Peanuts:

Pulse Crops:

Forage Crops: