Soybean Expert: Drought Impacts Soil Microbials

Severe drought conditions limited soybean production (6.2% per-acre yield decline from 2011) across much of the U.S. in 2012. The implications of the 2012 drought may progress well into the 2013 growing season. One area of concern among growers is the impact of the drought on soil microbial populations, most importantly Bradyrhizobium japonicum. Soybeans live in a symbiotic (mutually beneficial) relationship with B. japonicum. The soybean plant provides nutrients and a protective growing environment for the rhizobia, says UW-Madison Soybean Specialist Shawn Conley.

In turn, the rhizobia “fix” atmospheric nitrogen into ammonia (NH3), which can then be used by the soybean plant. For this relationship to exist and benefit the soybean plant, effective nitrogen-fixing bacteria must be present in the soil in relatively high numbers at planting time.

To date, little research has been published that quantifies the impact of soil desiccation (i.e., drought) on endemic B. japonicum populations. Researchers back in 1979 reported a biphasic decline in Rhizobium japonicum numbers in soils undergoing drying. The initial rapid phase of R. japonicum loss coincided with major water loss (simulated drought) whereas the secondary and subsequently slower decline in numbers was governed by the soil water content of specific soils. The same researchers also noted that organic matter content provided little protection against R. japonicum desiccation and loss.

In a parallel study in 1982, similar results were reported when comparing strains of R. japonicum and cowpea rhizobia under desiccation. “As one would expect, variation exists among Rhizobium species as well as individual isolates within species in their response to soil desiccation, though significant losses were evident regardless of species or isolate,” reports Conley.

To further complicate the situation, most soybean acres will be planted into corn ground that was subjected to severe drought stress. This suggests that excess nitrogen may be present for the 2013 soybean crop, Conley continues.

In excess situations soybean will generally utilize the background nitrogen prior to initiating maximum N fixation. This may lead to luxurious early season growth, which in fields with a history of white mold, may cause problems if weather conditions are conducive. High soil N reserves may also lead to increased lodging.

“In either case, manage your soybean crop accordingly to minimize risk of white mold or lodging. This can be accomplished through variety selection (i.e. white mold tolerance, short statured soybean cultivars or good lodging tolerance), decreasing seeding rates, and proper scouting to time fungicide applications if needed,” he says.

“I am not advocating that every soybean acre automatically receive an inoculant treatment, however, the small amount of research that is available on the topic does suggest that growers may expect lowered B. japonicum populations going into the 2013 growing season,” he concludes.

Topics:

Leave a Reply

Crop Inputs Stories

Syngenta Sign
FungicidesSyngenta’s Newest Fungicide Receives EPA Approval
September 1, 2015
Syngenta announced today that its newest succinate dehydrogenase inhibitor (SDHI) fungicide – Solatenol – has received registration from EPA and Read More
Flooded corn in Indiana
Crop InputsDelaying The Fertilizer Decision
September 1, 2015
Comments gathered from several retailers recently evidenced a classic good-news-bad-news scenario. Good news is prices and supplies of nitrogen, phosphate, Read More
Crop InputsMonsanto, FMC Expand Roundup Ready PLUS Platform
August 31, 2015
FMC Corp. and Monsanto Co. announced today an expanded agreement to continue their participation in the Roundup Ready PLUS Crop Read More
FertilizerFall-Applied Phosphorus: A Rooted Investment
August 28, 2015
As commodity prices decrease and input prices continue to rise, farmers are seeking more efficient strategies for meeting a high Read More
Top 100 Articles
Crop InputsLand ‘O Lakes, United Suppliers Finalize Merger
August 24, 2015
According to a press release on August 24, owners of United Suppliers, Inc. and members of Land O’Lakes, Inc. “have Read More
West Central Cooperative, Jefferson, IA
CropLife 100Iowa Cooperatives To Explore Unification
August 19, 2015
The boards of directors at two of Iowa’s leading farmer-owned cooperatives yesterday signed a letter of intent to study the Read More
CropLife 100Southern States Coop Hosting Drone Flight This Friday
August 3, 2015
Southern States Cooperative — No. 9 on the CropLife 100 — is hosting an FAA-approved drone demonstration at Grandview Farms Read More
CropLife 100Aligned Ag Distributors Adds Four New Owners
July 30, 2015
Aligned Ag Distributors LLC has announced the addition of four new customer/owners to Franklin Holding Co. LLC. They are: The Read More
CropLife 100Pinnacle Purchases California-Based Specialty Crops Retailer
July 20, 2015
Pinnacle Agriculture Holdings has successfully acquired California-based NH3 Service Co.  Operating as part of Pinnacle’s Performance Agriculture brand, the new locations Read More
Asmus Farm Supply liquid fertilizer facility features 20,000 square feet
CropLife 100Slideshow: Asmus Farm Supply Shows Off Its New Liquid Fertilizer Facility
July 15, 2015
Asmus Farm Supply, Rake, IA, recently added a new liquid fertilizer facility to its company operations. The new liquid fertilizer Read More
Latest News
SprayersNORAC Active Wing Roll Slated For More Sprayers
September 1, 2015
NORAC Systems, a member of the Topcon Positioning Group, announces the release of Active Wing Roll for RoGator, Apache, New Read More
Syngenta Sign
FungicidesSyngenta’s Newest Fungicide Receives EPA Approval
September 1, 2015
Syngenta announced today that its newest succinate dehydrogenase inhibitor (SDHI) fungicide – Solatenol – has received registration from EPA and Read More
Flooded corn in Indiana
Crop InputsDelaying The Fertilizer Decision
September 1, 2015
Comments gathered from several retailers recently evidenced a classic good-news-bad-news scenario. Good news is prices and supplies of nitrogen, phosphate, Read More
StewardshipBee Buffer Strip Initiative Seeks 100 Ohio Farmers
August 31, 2015
The U.S. Bee Buffer Project, an initiative of the Pollinator Partnership (P2), Burt’s Bees and The Burt’s Bees Greater Good Read More
2015 ShowStopper Award, MAGIE
EquipmentA ShowStopper From Case IH: The Patriot 2250
August 31, 2015
For nine years now, visitors to the yearly Midwest AG Industries Exposition (MAGIE) show have been tasked with not only Read More
Crop InputsMonsanto, FMC Expand Roundup Ready PLUS Platform
August 31, 2015
FMC Corp. and Monsanto Co. announced today an expanded agreement to continue their participation in the Roundup Ready PLUS Crop Read More
Deere Nutrient Applicator
Eric SfiligojThe Good & Bad News From MAGIE
August 31, 2015
As I write this column, I’ve just returned from the annual Midwest AG Industries (MAGIE) trade show in Bloomington, IL. Read More
CPS Morenci receiving its 4R certification
StewardshipCPS Morenci Becomes First Michigan Facility Certified I…
August 31, 2015
The 4R Nutrient Stewardship Certification Program has announced that Crop Production Services, Inc.’s facility located in Morenci, MI, has been Read More
EquipmentDeere Announces Soucy Track Distribution Alliance
August 28, 2015
John Deere announces an alliance with Soucy Track to sell and distribute products through the John Deere dealer channel. “This Read More
FertilizerFall-Applied Phosphorus: A Rooted Investment
August 28, 2015
As commodity prices decrease and input prices continue to rise, farmers are seeking more efficient strategies for meeting a high Read More
Monsanto Sign
Crop InputsWhat’s Next For Monsanto, Syngenta?
August 28, 2015
After dropping its $47 billion bid to take over Swiss agribusiness firm Syngenta, Monsanto may be turning its focus to Read More
Golden Harvest Corn stalks
Crop InputsMonsanto: Syngenta Not The Only Horse In Crop Protectio…
August 28, 2015
Monsanto Co, having ditched an audacious $46 billion (£30 billion) offer for Syngenta AG, may downshift to a humbler strategy Read More
ManagementConsolidation hits and a miss; And a look at China’s ch…
August 28, 2015
As Monsanto suspends its pursuit of Syngenta, consolidation news at the retail and distribution level heats up. CropLife magazine’s Executive Read More
Corn Field
MicronutrientsHuma Gro Introduces New Boron Liquid Nutrient Formulati…
August 28, 2015
BORO-MAX, a new boron (B) 10% liquid nutrient formulation, has been added to the Huma Gro product line. This new Read More
Crop InputsNFU: Monsanto Decision To Withdraw Syngenta Bid ‘…
August 26, 2015
National Farmers Union (NFU) President Roger Johnson said the organization was very pleased by the news that Monsanto has withdrawn Read More
Crop InputsMonsanto Withdraws Bid For Syngenta
August 26, 2015
Monsanto Co. abandoned its latest effort to acquire Syngenta AG, the world’s top maker of pesticides, after a sweetened bid Read More
Syngenta Sign
Crop InputsSyngenta Comments On Monsanto Announcement
August 26, 2015
The Board of Syngenta confirms that it received a verbal proposal from Monsanto to acquire the company at a price Read More
Case IH Patriot 2250 Sprayer
EquipmentHigh-powered Case IH Patriot 2250 Sprayer Pushes Throug…
August 26, 2015
Engineered with more muscle, the new 660-gallon-capacity Patriot 2250 sprayer features best-in-class horsepower, along with the fuel efficiency that comes Read More